diff --git a/src/edu/kit/informatik/ui/command/AddSwitch.java b/src/edu/kit/informatik/ui/command/AddSwitch.java
index bc77a30..9c47dc0 100644
--- a/src/edu/kit/informatik/ui/command/AddSwitch.java
+++ b/src/edu/kit/informatik/ui/command/AddSwitch.java
@@ -5,6 +5,12 @@ import edu.kit.informatik.model.Vector2D;
 import edu.kit.informatik.Terminal;
 import edu.kit.informatik.ui.InvalidInputException;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.ADD_SWITCH;
+import static edu.kit.informatik.ui.command.CommandFactory.VECTOR;
+
 /**
  * Command used to add a switch to the rail network.
  *
@@ -12,31 +18,21 @@ import edu.kit.informatik.ui.InvalidInputException;
  * @version 1.0
  */
 public class AddSwitch extends Command {
+    private static final Pattern ADD_SWITCH_ARGUMENTS
+            = Pattern.compile(" \\((" + VECTOR + ")\\) -> \\((" + VECTOR + ")\\),\\((" + VECTOR + ")\\)");
+
     /**
      * Start position of the switch to add.
      */
-    private final Vector2D start;
+    private Vector2D start;
     /**
      * End position 1 of the switch to add.
      */
-    private final Vector2D end1;
+    private Vector2D end1;
     /**
      * End position 2 of the switch to add.
      */
-    private final Vector2D end2;
-
-    /**
-     * Construct a new 'add switch' command.
-     * @param start start position
-     * @param end1 end position 1
-     * @param end2 end position 2
-     */
-    public AddSwitch(final Vector2D start, final Vector2D end1, final Vector2D end2) {
-        // make sure caller can not modify internal state
-        this.start = new Vector2D(start);
-        this.end1 = new Vector2D(end1);
-        this.end2 = new Vector2D(end2);
-    }
+    private Vector2D end2;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) throws InvalidInputException {
@@ -47,4 +43,18 @@ public class AddSwitch extends Command {
             Terminal.printLine(id);
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(ADD_SWITCH)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = ADD_SWITCH_ARGUMENTS.matcher(input.substring(ADD_SWITCH.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid add switch argument syntax");
+        }
+        start = Vector2D.parse(matcher.group(1));
+        end1 = Vector2D.parse(matcher.group(2));
+        end2 = Vector2D.parse(matcher.group(3));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/AddTrack.java b/src/edu/kit/informatik/ui/command/AddTrack.java
index 2f873ad..0a1cf89 100644
--- a/src/edu/kit/informatik/ui/command/AddTrack.java
+++ b/src/edu/kit/informatik/ui/command/AddTrack.java
@@ -5,6 +5,12 @@ import edu.kit.informatik.model.Vector2D;
 import edu.kit.informatik.Terminal;
 import edu.kit.informatik.ui.InvalidInputException;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.ADD_TRACK;
+import static edu.kit.informatik.ui.command.CommandFactory.VECTOR;
+
 /**
  * Command used to add a track to the rail network.
  *
@@ -12,25 +18,17 @@ import edu.kit.informatik.ui.InvalidInputException;
  * @version 1.0
  */
 public class AddTrack extends Command {
+    private static final Pattern ADD_TRACK_ARGUMENTS
+            = Pattern.compile(" \\((" + VECTOR + ")\\) -> \\((" + VECTOR + ")\\)");
+
     /**
      * Start position of the new track.
      */
-    private final Vector2D start;
+    private Vector2D start;
     /**
      * End position of the new track.
      */
-    private final Vector2D end;
-
-    /**
-     * Construct a new 'add track' command.
-     * @param start position of the start of the track
-     * @param end position of the end of the track
-     */
-    public AddTrack(final Vector2D start, final Vector2D end) {
-        // make sure caller can not modify internal state
-        this.start = new Vector2D(start);
-        this.end = new Vector2D(end);
-    }
+    private Vector2D end;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) throws InvalidInputException {
@@ -41,4 +39,17 @@ public class AddTrack extends Command {
             Terminal.printLine(id);
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(ADD_TRACK)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = ADD_TRACK_ARGUMENTS.matcher(input.substring(ADD_TRACK.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid add track argument syntax");
+        }
+        start = Vector2D.parse(matcher.group(1));
+        end = Vector2D.parse(matcher.group(2));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/AddTrain.java b/src/edu/kit/informatik/ui/command/AddTrain.java
index 1541004..43762ce 100644
--- a/src/edu/kit/informatik/ui/command/AddTrain.java
+++ b/src/edu/kit/informatik/ui/command/AddTrain.java
@@ -5,6 +5,13 @@ import edu.kit.informatik.model.RollingStock;
 import edu.kit.informatik.Terminal;
 import edu.kit.informatik.ui.InvalidInputException;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.ADD_TRAIN;
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
+import static edu.kit.informatik.ui.command.CommandFactory.ROLLING_STOCK_IDENTIFIER;
+
 /**
  * Command used to construct a new train or modify an existing train.
  *
@@ -12,24 +19,17 @@ import edu.kit.informatik.ui.InvalidInputException;
  * @version 1.0
  */
 public class AddTrain extends Command {
+    private static final Pattern ADD_TRAIN_ARGUMENTS
+            = Pattern.compile(" (" + NUMBER + ") (" + ROLLING_STOCK_IDENTIFIER + ")");
+
     /**
      * Identifier of the train to add or modify.
      */
-    private final int trainId;
+    private int trainId;
     /**
      * Identifier of the rolling stock to add.
      */
-    private final String rollingStockId;
-
-    /**
-     * Construct a new 'add train' command.
-     * @param trainId identifier of the train to be added/modified
-     * @param rollingStockId identifier of the rolling to be added to the train
-     */
-    public AddTrain(final int trainId, final String rollingStockId) {
-        this.trainId = trainId;
-        this.rollingStockId = rollingStockId;
-    }
+    private String rollingStockId;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) throws InvalidInputException {
@@ -38,4 +38,17 @@ public class AddTrain extends Command {
         Terminal.printLine(String.format("%s %s added to train %d",
                 rollingStock.description(), rollingStock.getIdentifier(), trainId));
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(ADD_TRAIN)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = ADD_TRAIN_ARGUMENTS.matcher(input.substring(ADD_TRAIN.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid add train arguments");
+        }
+        trainId = Integer.parseInt(matcher.group(1));
+        rollingStockId = matcher.group(2);
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/Command.java b/src/edu/kit/informatik/ui/command/Command.java
index 4559680..3adf33f 100644
--- a/src/edu/kit/informatik/ui/command/Command.java
+++ b/src/edu/kit/informatik/ui/command/Command.java
@@ -17,4 +17,11 @@ public abstract class Command {
      * @throws InvalidInputException on invalid user input
      */
     public abstract void apply(ModelRailwaySimulation simulation) throws InvalidInputException;
+
+    /**
+     * Parse user input into the command object.
+     * @param input one line of user input
+     * @throws InvalidInputException if user input is in any way invalid
+     */
+    public abstract void parse(String input) throws InvalidInputException;
 }
diff --git a/src/edu/kit/informatik/ui/command/CommandFactory.java b/src/edu/kit/informatik/ui/command/CommandFactory.java
index cf3d687..3871a81 100644
--- a/src/edu/kit/informatik/ui/command/CommandFactory.java
+++ b/src/edu/kit/informatik/ui/command/CommandFactory.java
@@ -1,13 +1,7 @@
 package edu.kit.informatik.ui.command;
 
-import edu.kit.informatik.model.Vector2D;
-import edu.kit.informatik.ui.CoachType;
-import edu.kit.informatik.ui.EngineType;
 import edu.kit.informatik.ui.InvalidInputException;
 
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
 /**
  * Factory used to parse user input into commands.
  *
@@ -15,48 +9,30 @@ import java.util.regex.Pattern;
  * @version 1.0
  */
 public final class CommandFactory {
-    private static final String NUMBER = "[+-]?\\d+";
-    private static final String VECTOR = NUMBER + "," + NUMBER;
-    private static final String ALPHANUMERIC_WORD = "[\\p{L}\\d]+";
-    private static final String ROLLING_STOCK_IDENTIFIER
+    public static final String NUMBER = "[+-]?\\d+";
+    public static final String VECTOR = NUMBER + "," + NUMBER;
+    public static final String ALPHANUMERIC_WORD = "[\\p{L}\\d]+";
+    public static final String ROLLING_STOCK_IDENTIFIER
             = "(" + ALPHANUMERIC_WORD + "-" + ALPHANUMERIC_WORD + ")|W" + NUMBER;
 
-    private static final String ADD_TRACK = "add track";
-    private static final Pattern ADD_TRACK_ARGUMENTS
-        = Pattern.compile(" \\((" + VECTOR + ")\\) -> \\((" + VECTOR + ")\\)");
-    private static final String ADD_SWITCH = "add switch";
-    private static final Pattern ADD_SWITCH_ARGUMENTS
-        = Pattern.compile(" \\((" + VECTOR + ")\\) -> \\((" + VECTOR + ")\\),\\((" + VECTOR + ")\\)");
-    private static final String DELETE_TRACK = "delete track";
-    private static final String LIST_TRACKS = "list tracks";
-    private static final String SET_SWITCH = "set switch";
-    private static final Pattern SET_SWITCH_ARGUMENTS
-        = Pattern.compile(" (" + NUMBER + ") position \\((" + VECTOR + ")\\)");
-    private static final String CREATE_ENGINE = "create engine";
-    private static final Pattern CREATE_ENGINE_ARGUMENTS
-        = Pattern.compile(" (electrical|diesel|steam) (" + ALPHANUMERIC_WORD + ") (" + ALPHANUMERIC_WORD + ") (" + NUMBER + ") (true|false) (true|false)");
-    private static final String LIST_ENGINES = "list engines";
-    private static final String CREATE_COACH = "create coach";
-    private static final Pattern CREATE_COACH_ARGUMENTS
-        = Pattern.compile(" (passenger|freight|special) (" + NUMBER + ") (true|false) (true|false)");
-    private static final String LIST_COACHES = "list coaches";
-    private static final String CREATE_TRAIN_SET = "create train-set";
-    private static final Pattern CREATE_TRAIN_SET_ARGUMENTS
-        = Pattern.compile(" (" + ALPHANUMERIC_WORD + ") (" + ALPHANUMERIC_WORD + ") (" + NUMBER + ") (true|false) (true|false)");
-    private static final String LIST_TRAIN_SETS = "list train-sets";
-    private static final String DELETE_ROLLING_STOCK = "delete rolling stock";
-    private static final Pattern DELETE_ROLLING_STOCK_ARGUMENT
-        = Pattern.compile(" (" + ROLLING_STOCK_IDENTIFIER + ")");
-    private static final String ADD_TRAIN = "add train";
-    private static final Pattern ADD_TRAIN_ARGUMENTS
-        = Pattern.compile(" (" + NUMBER + ") (" + ROLLING_STOCK_IDENTIFIER + ")");
-    private static final String DELETE_TRAIN = "delete train";
-    private static final String LIST_TRAINS = "list trains";
-    private static final String SHOW_TRAIN = "show train";
-    private static final String PUT_TRAIN = "put train";
-    private static final Pattern PUT_TRAIN_ARGUMENTS
-        = Pattern.compile(" (" + NUMBER + ") at \\((" + VECTOR + ")\\) in direction (" + VECTOR + ")");
-    private static final String STEP = "step";
+    public static final String ADD_TRACK = "add track";
+    public static final String ADD_SWITCH = "add switch";
+    public static final String DELETE_TRACK = "delete track";
+    public static final String LIST_TRACKS = "list tracks";
+    public static final String SET_SWITCH = "set switch";
+    public static final String CREATE_ENGINE = "create engine";
+    public static final String LIST_ENGINES = "list engines";
+    public static final String CREATE_COACH = "create coach";
+    public static final String LIST_COACHES = "list coaches";
+    public static final String CREATE_TRAIN_SET = "create train-set";
+    public static final String LIST_TRAIN_SETS = "list train-sets";
+    public static final String DELETE_ROLLING_STOCK = "delete rolling stock";
+    public static final String ADD_TRAIN = "add train";
+    public static final String DELETE_TRAIN = "delete train";
+    public static final String LIST_TRAINS = "list trains";
+    public static final String SHOW_TRAIN = "show train";
+    public static final String PUT_TRAIN = "put train";
+    public static final String STEP = "step";
 
     /**
      * Utility class -> private constructor.
@@ -72,158 +48,47 @@ public final class CommandFactory {
      * @throws InvalidInputException if user input is invalid
      */
     public static Command getCommand(final String command) throws InvalidInputException {
+        Command commandObject;
         if (command.startsWith(ADD_TRACK)) {
-            String arguments = command.substring(ADD_TRACK.length());
-            Matcher matcher = ADD_TRACK_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid add track argument syntax");
-            }
-            Vector2D start = Vector2D.parse(matcher.group(1));
-            Vector2D end = Vector2D.parse(matcher.group(2));
-            return new AddTrack(start, end);
+            commandObject = new AddTrack();
         } else if (command.startsWith(ADD_SWITCH)) {
-            String arguments = command.substring(ADD_SWITCH.length());
-            Matcher matcher = ADD_SWITCH_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid add switch argument syntax");
-            }
-            Vector2D start = Vector2D.parse(matcher.group(1));
-            Vector2D end1 = Vector2D.parse(matcher.group(2));
-            Vector2D end2 = Vector2D.parse(matcher.group(3));
-            return new AddSwitch(start, end1, end2);
+            commandObject = new AddSwitch();
         } else if (command.startsWith(DELETE_TRACK)) {
-            String argument = command.substring(DELETE_TRACK.length());
-            if (!argument.matches(" " + NUMBER)) {
-                throw new InvalidInputException("invalid/missing delete track argument");
-            }
-            int id = Integer.parseInt(argument.substring(1));
-            return new DeleteTrack(id);
+            commandObject = new DeleteTrack();
         } else if (command.startsWith(LIST_TRACKS)) {
-            if (command.length() > LIST_TRACKS.length()) {
-                throw new InvalidInputException("too many arguments for list tracks");
-            }
-            return new ListTracks();
+            commandObject = new ListTracks();
         } else if (command.startsWith(SET_SWITCH)) {
-            String arguments = command.substring(SET_SWITCH.length());
-            Matcher matcher = SET_SWITCH_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid set switch argument syntax");
-            }
-            int id = Integer.parseInt(matcher.group(1));
-            Vector2D point = Vector2D.parse(matcher.group(2));
-            return new SetSwitch(id, point);
+            commandObject = new SetSwitch();
         } else if (command.startsWith(CREATE_ENGINE)) {
-            String arguments = command.substring(CREATE_ENGINE.length());
-            Matcher matcher = CREATE_ENGINE_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid create engine argument syntax");
-            }
-            EngineType type = EngineType.parse(matcher.group(1));
-            String series = matcher.group(2);
-            if ("W".equals(series)) {
-                throw new InvalidInputException("invalid engine class/series");
-            }
-            String name = matcher.group(3);
-            int length = Integer.parseInt(matcher.group(4));
-            boolean couplingFront = Boolean.parseBoolean(matcher.group(5));
-            boolean couplingBack = Boolean.parseBoolean(matcher.group(6));
-            return new CreateEngine(type, series, name, length, couplingFront, couplingBack);
+            commandObject = new CreateEngine();
         } else if (command.startsWith(LIST_ENGINES)) {
-            if (command.length() > LIST_ENGINES.length()) {
-                throw new InvalidInputException("too many list engines arguments");
-            }
-            return new ListEngines();
+            commandObject = new ListEngines();
         } else if (command.startsWith(CREATE_COACH)) {
-            String arguments = command.substring(CREATE_COACH.length());
-            Matcher matcher = CREATE_COACH_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid create coach arguments");
-            }
-            CoachType type = CoachType.parse(matcher.group(1));
-            int length = Integer.parseInt(matcher.group(2));
-            boolean couplingFront = Boolean.parseBoolean(matcher.group(3));
-            boolean couplingBack = Boolean.parseBoolean(matcher.group(4));
-            return new CreateCoach(type, length, couplingFront, couplingBack);
+            commandObject = new CreateCoach();
         } else if (command.startsWith(LIST_COACHES)) {
-            if (command.length() > LIST_COACHES.length()) {
-                throw new InvalidInputException("too many list coaches arguments");
-            }
-            return new ListCoaches();
+            commandObject = new ListCoaches();
         } else if (command.startsWith(CREATE_TRAIN_SET)) {
-            String arguments = command.substring(CREATE_TRAIN_SET.length());
-            Matcher matcher = CREATE_TRAIN_SET_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid create train-set arguments");
-            }
-            String series = matcher.group(1);
-            if ("W".equals(series)) {
-                throw new InvalidInputException("invalid train-set class/series");
-            }
-            String name = matcher.group(2);
-            int length = Integer.parseInt(matcher.group(3));
-            boolean couplingFront = Boolean.parseBoolean(matcher.group(4));
-            boolean couplingBack = Boolean.parseBoolean(matcher.group(5));
-            return new CreateTrainSet(series, name, length, couplingFront, couplingBack);
+            commandObject = new CreateTrainSet();
         } else if (command.startsWith(LIST_TRAIN_SETS)) {
-            if (command.length() > LIST_TRAIN_SETS.length()) {
-                throw new InvalidInputException("too many list train-sets arguments");
-            }
-            return new ListTrainSets();
+            commandObject = new ListTrainSets();
         } else if (command.startsWith(DELETE_ROLLING_STOCK)) {
-            String argument = command.substring(DELETE_ROLLING_STOCK.length());
-            Matcher matcher = DELETE_ROLLING_STOCK_ARGUMENT.matcher(argument);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid delete rolling stock argument");
-            }
-            String id = matcher.group(1);
-            return new DeleteRollingStock(id);
+            commandObject = new DeleteRollingStock();
         } else if (command.startsWith(ADD_TRAIN)) {
-            String arguments = command.substring(ADD_TRAIN.length());
-            Matcher matcher = ADD_TRAIN_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid add train arguments");
-            }
-            int trainId = Integer.parseInt(matcher.group(1));
-            String rollingStockId = matcher.group(2);
-            return new AddTrain(trainId, rollingStockId);
+            commandObject = new AddTrain();
         } else if (command.startsWith(DELETE_TRAIN)) {
-            String argument = command.substring(DELETE_TRAIN.length());
-            if (!argument.matches(" " + NUMBER)) {
-                throw new InvalidInputException("invalid delete train argument");
-            }
-            int id = Integer.parseInt(argument.substring(1));
-            return new DeleteTrain(id);
+            commandObject = new DeleteTrain();
         } else if (command.startsWith(LIST_TRAINS)) {
-            if (command.length() > LIST_TRAINS.length()) {
-                throw new InvalidInputException("too many list trains arguments");
-            }
-            return new ListTrains();
+            commandObject = new ListTrains();
         } else if (command.startsWith(SHOW_TRAIN)) {
-            String argument = command.substring(SHOW_TRAIN.length());
-            if (!argument.matches(" " + NUMBER)) {
-                throw new InvalidInputException("invalid show train argument");
-            }
-            int id = Integer.parseInt(argument.substring(1));
-            return new ShowTrain(id);
+            commandObject = new ShowTrain();
         } else if (command.startsWith(PUT_TRAIN)) {
-            String arguments = command.substring(PUT_TRAIN.length());
-            Matcher matcher = PUT_TRAIN_ARGUMENTS.matcher(arguments);
-            if (!matcher.matches()) {
-                throw new InvalidInputException("invalid put train arguments");
-            }
-            int id = Integer.parseInt(matcher.group(1));
-            Vector2D point = Vector2D.parse(matcher.group(2));
-            Vector2D direction = Vector2D.parse(matcher.group(3));
-            return new PutTrain(id, point, direction);
+            commandObject = new PutTrain();
         } else if (command.startsWith(STEP)) {
-            String argument = command.substring(STEP.length());
-            if (!argument.matches(" [+-]?\\d+")) {
-                throw new InvalidInputException("invalid step argument");
-            }
-            short speed = Short.parseShort(argument.substring(1));
-            return new Step(speed);
+            commandObject = new Step();
         } else {
             throw new InvalidInputException("unknown command");
         }
+        commandObject.parse(command);
+        return commandObject;
     }
 }
diff --git a/src/edu/kit/informatik/ui/command/CreateCoach.java b/src/edu/kit/informatik/ui/command/CreateCoach.java
index d4bcc26..66714e7 100644
--- a/src/edu/kit/informatik/ui/command/CreateCoach.java
+++ b/src/edu/kit/informatik/ui/command/CreateCoach.java
@@ -5,6 +5,12 @@ import edu.kit.informatik.model.ModelRailwaySimulation;
 import edu.kit.informatik.Terminal;
 import edu.kit.informatik.ui.InvalidInputException;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.CREATE_COACH;
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
+
 /**
  * Command used to create a single coach.
  *
@@ -12,40 +18,25 @@ import edu.kit.informatik.ui.InvalidInputException;
  * @version 1.0
  */
 public class CreateCoach extends Command {
+    private static final Pattern CREATE_COACH_ARGUMENTS
+            = Pattern.compile(" (passenger|freight|special) (" + NUMBER + ") (true|false) (true|false)");
+
     /**
      * Type of the new coach.
      */
-    private final CoachType type;
+    private CoachType type;
     /**
      * Length of the new coach.
      */
-    private final int length;
+    private int length;
     /**
      * Whether the new coach should have a front coupling.
      */
-    private final boolean couplingFront;
+    private boolean couplingFront;
     /**
      * Whether the new coach should have a back coupling.
      */
-    private final boolean couplingBack;
-
-    /**
-     * Create a new 'create coach' command.
-     * @param type type of the coach
-     * @param length length of the coach
-     * @param couplingFront whether the coach should have a front coupling
-     * @param couplingBack whether the coach should have a back coupling
-     */
-    public CreateCoach(final CoachType type, final int length,
-                       final boolean couplingFront, final boolean couplingBack) {
-        if (type == null) {
-            throw new IllegalArgumentException("coach type is null");
-        }
-        this.type = type;
-        this.length = length;
-        this.couplingFront = couplingFront;
-        this.couplingBack = couplingBack;
-    }
+    private boolean couplingBack;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) throws InvalidInputException {
@@ -56,4 +47,19 @@ public class CreateCoach extends Command {
             Terminal.printLine(id);
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(CREATE_COACH)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = CREATE_COACH_ARGUMENTS.matcher(input.substring(CREATE_COACH.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid create coach arguments");
+        }
+        type = CoachType.parse(matcher.group(1));
+        length = Integer.parseInt(matcher.group(2));
+        couplingFront = Boolean.parseBoolean(matcher.group(3));
+        couplingBack = Boolean.parseBoolean(matcher.group(4));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/CreateEngine.java b/src/edu/kit/informatik/ui/command/CreateEngine.java
index fe15dc6..8075837 100644
--- a/src/edu/kit/informatik/ui/command/CreateEngine.java
+++ b/src/edu/kit/informatik/ui/command/CreateEngine.java
@@ -9,6 +9,13 @@ import edu.kit.informatik.model.SteamEngine;
 import edu.kit.informatik.ui.EngineType;
 import edu.kit.informatik.ui.InvalidInputException;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.ALPHANUMERIC_WORD;
+import static edu.kit.informatik.ui.command.CommandFactory.CREATE_ENGINE;
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
+
 /**
  * Command used to create a single engine.
  *
@@ -16,52 +23,33 @@ import edu.kit.informatik.ui.InvalidInputException;
  * @version 1.0
  */
 public class CreateEngine extends Command {
+    private static final Pattern CREATE_ENGINE_ARGUMENTS
+        = Pattern.compile(" (electrical|diesel|steam) (" + ALPHANUMERIC_WORD + ") (" + ALPHANUMERIC_WORD + ") (" + NUMBER + ") (true|false) (true|false)");
+
     /**
      * Type of the new engine.
      */
-    private final EngineType type;
+    private EngineType type;
     /**
      * Series (class) of the new engine.
      */
-    private final String series;
+    private String series;
     /**
      * Name of the new engine.
      */
-    private final String name;
+    private String name;
     /**
      * Length of the new engine.
      */
-    private final int length;
+    private int length;
     /**
      * Whether the new engine should have a front coupling.
      */
-    private final boolean couplingFront;
+    private boolean couplingFront;
     /**
      * Whether the new engine should have a back coupling.
      */
-    private final boolean couplingBack;
-
-    /**
-     * Construct a new 'create engine' command.
-     * @param type type of the engine
-     * @param series series/class of the engine
-     * @param name name of the engine
-     * @param length length of the engine
-     * @param couplingFront whether the new engine should have a front coupling
-     * @param couplingBack whether the new engine should have a back coupling
-     */
-    public CreateEngine(final EngineType type, final String series, final String name, final int length,
-                        final boolean couplingFront, final boolean couplingBack) {
-        if (type == null) {
-            throw new IllegalArgumentException("engine type is null!");
-        }
-        this.type = type;
-        this.series = series;
-        this.name = name;
-        this.length = length;
-        this.couplingFront = couplingFront;
-        this.couplingBack = couplingBack;
-    }
+    private boolean couplingBack;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) throws InvalidInputException {
@@ -82,4 +70,24 @@ public class CreateEngine extends Command {
         simulation.createEngine(engine);
         Terminal.printLine(engine.getIdentifier());
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(CREATE_ENGINE)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = CREATE_ENGINE_ARGUMENTS.matcher(input.substring(CREATE_ENGINE.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid create engine argument syntax");
+        }
+        type = EngineType.parse(matcher.group(1));
+        series = matcher.group(2);
+        if ("W".equals(series)) {
+            throw new InvalidInputException("invalid engine class/series");
+        }
+        name = matcher.group(3);
+        length = Integer.parseInt(matcher.group(4));
+        couplingFront = Boolean.parseBoolean(matcher.group(5));
+        couplingBack = Boolean.parseBoolean(matcher.group(6));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/CreateTrainSet.java b/src/edu/kit/informatik/ui/command/CreateTrainSet.java
index 94aa3df..a8b770d 100644
--- a/src/edu/kit/informatik/ui/command/CreateTrainSet.java
+++ b/src/edu/kit/informatik/ui/command/CreateTrainSet.java
@@ -5,6 +5,13 @@ import edu.kit.informatik.Terminal;
 import edu.kit.informatik.model.TrainSet;
 import edu.kit.informatik.ui.InvalidInputException;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.ALPHANUMERIC_WORD;
+import static edu.kit.informatik.ui.command.CommandFactory.CREATE_TRAIN_SET;
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
+
 /**
  * Command used to add a new train set.
  *
@@ -12,43 +19,29 @@ import edu.kit.informatik.ui.InvalidInputException;
  * @version Arne Keller
  */
 public class CreateTrainSet extends Command {
+    private static final Pattern CREATE_TRAIN_SET_ARGUMENTS
+        = Pattern.compile(" (" + ALPHANUMERIC_WORD + ") (" + ALPHANUMERIC_WORD + ") (" + NUMBER + ") (true|false) (true|false)");
+
     /**
      * Series (class) of the new train set.
      */
-    private final String series;
+    private String series;
     /**
      * Name of the new train set.
      */
-    private final String name;
+    private String name;
     /**
      * Length of the new train set.
      */
-    private final int length;
+    private int length;
     /**
      * Whether the new train set should have front coupling.
      */
-    private final boolean couplingFront;
+    private boolean couplingFront;
     /**
      * Whether the new train set should have a back coupling.
      */
-    private final boolean couplingBack;
-
-    /**
-     * Construct a new 'create train-set' command.
-     * @param series series/class of the train set
-     * @param name name of the train set
-     * @param length length of the train set
-     * @param couplingFront whether the train set should have a front coupling
-     * @param couplingBack whether the train set should have a back coupling
-     */
-    public CreateTrainSet(final String series, final String name, final int length,
-                          final boolean couplingFront, final boolean couplingBack) {
-        this.series = series;
-        this.name = name;
-        this.length = length;
-        this.couplingFront = couplingFront;
-        this.couplingBack = couplingBack;
-    }
+    private boolean couplingBack;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) throws InvalidInputException {
@@ -56,4 +49,23 @@ public class CreateTrainSet extends Command {
         simulation.createTrainSet(trainSet);
         Terminal.printLine(trainSet.getIdentifier());
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(CREATE_TRAIN_SET)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = CREATE_TRAIN_SET_ARGUMENTS.matcher(input.substring(CREATE_TRAIN_SET.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid create train-set arguments");
+        }
+        series = matcher.group(1);
+        if ("W".equals(series)) {
+            throw new InvalidInputException("invalid train-set class/series");
+        }
+        name = matcher.group(2);
+        length = Integer.parseInt(matcher.group(3));
+        couplingFront = Boolean.parseBoolean(matcher.group(4));
+        couplingBack = Boolean.parseBoolean(matcher.group(5));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/DeleteRollingStock.java b/src/edu/kit/informatik/ui/command/DeleteRollingStock.java
index 1ce3e07..f75f613 100644
--- a/src/edu/kit/informatik/ui/command/DeleteRollingStock.java
+++ b/src/edu/kit/informatik/ui/command/DeleteRollingStock.java
@@ -2,6 +2,13 @@ package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
 import edu.kit.informatik.Terminal;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.DELETE_ROLLING_STOCK;
+import static edu.kit.informatik.ui.command.CommandFactory.ROLLING_STOCK_IDENTIFIER;
 
 /**
  * Command used to delete rolling stock.
@@ -10,18 +17,13 @@ import edu.kit.informatik.Terminal;
  * @version 1.0
  */
 public class DeleteRollingStock extends Command {
+    private static final Pattern DELETE_ROLLING_STOCK_ARGUMENT
+            = Pattern.compile(" (" + ROLLING_STOCK_IDENTIFIER + ")");
+
     /**
      * Identifier of the rolling stock to delete.
      */
-    private final String id;
-
-    /**
-     * Construct a new 'delete rolling stock' command.
-     * @param id identifier of the rolling stock to delete
-     */
-    public DeleteRollingStock(final String id) {
-        this.id = id;
-    }
+    private String id;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) {
@@ -31,4 +33,16 @@ public class DeleteRollingStock extends Command {
             Terminal.printError("could not delete rolling stock");
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(DELETE_ROLLING_STOCK)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = DELETE_ROLLING_STOCK_ARGUMENT.matcher(input.substring(DELETE_ROLLING_STOCK.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid delete rolling stock argument");
+        }
+        id = matcher.group(1);
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/DeleteTrack.java b/src/edu/kit/informatik/ui/command/DeleteTrack.java
index 12ca58d..bac78fd 100644
--- a/src/edu/kit/informatik/ui/command/DeleteTrack.java
+++ b/src/edu/kit/informatik/ui/command/DeleteTrack.java
@@ -2,6 +2,10 @@ package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
 import edu.kit.informatik.Terminal;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.DELETE_TRACK;
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
 
 /**
  * Command used to delete a track or switch.
@@ -13,15 +17,7 @@ public class DeleteTrack extends Command {
     /**
      * Identifier of the rail to delete.
      */
-    private final int id;
-
-    /**
-     * Construct a new 'delete track' command.
-     * @param id identifier of the track/switch to delete
-     */
-    public DeleteTrack(final int id) {
-        this.id = id;
-    }
+    private int id;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) {
@@ -31,4 +27,16 @@ public class DeleteTrack extends Command {
             Terminal.printError("could not delete rail segment");
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(DELETE_TRACK)) {
+            throw new InvalidInputException("unknown command");
+        }
+        String argument = input.substring(DELETE_TRACK.length());
+        if (!argument.matches(" " + NUMBER)) {
+            throw new InvalidInputException("invalid/missing delete track argument");
+        }
+        id = Integer.parseInt(argument.substring(1));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/DeleteTrain.java b/src/edu/kit/informatik/ui/command/DeleteTrain.java
index 9f04422..1d64d48 100644
--- a/src/edu/kit/informatik/ui/command/DeleteTrain.java
+++ b/src/edu/kit/informatik/ui/command/DeleteTrain.java
@@ -2,6 +2,10 @@ package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
 import edu.kit.informatik.Terminal;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.DELETE_TRAIN;
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
 
 /**
  * Command used to delete a train, without deleting rolling stock of the train.
@@ -13,15 +17,7 @@ public class DeleteTrain extends Command {
     /**
      * Identifier of the train to delete.
      */
-    private final int id;
-
-    /**
-     * Construct a new 'delete train' command.
-     * @param id identifier of the train to delete
-     */
-    public DeleteTrain(final int id) {
-        this.id = id;
-    }
+    private int id;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) {
@@ -31,4 +27,16 @@ public class DeleteTrain extends Command {
             Terminal.printError("could not remove train");
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(DELETE_TRAIN)) {
+            throw new InvalidInputException("unknown command");
+        }
+        String argument = input.substring(DELETE_TRAIN.length());
+        if (!argument.matches(" " + NUMBER)) {
+            throw new InvalidInputException("invalid delete train argument");
+        }
+        id = Integer.parseInt(argument.substring(1));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/ListCoaches.java b/src/edu/kit/informatik/ui/command/ListCoaches.java
index 27100a9..7f81747 100644
--- a/src/edu/kit/informatik/ui/command/ListCoaches.java
+++ b/src/edu/kit/informatik/ui/command/ListCoaches.java
@@ -1,6 +1,9 @@
 package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.LIST_COACHES;
 
 /**
  * Command used to print a list of coaches.
@@ -13,4 +16,14 @@ public class ListCoaches extends Command {
     public void apply(final ModelRailwaySimulation simulation) {
         simulation.printCoaches();
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(LIST_COACHES)) {
+            throw new InvalidInputException("unknown command");
+        }
+        if (input.length() > LIST_COACHES.length()) {
+            throw new InvalidInputException("too many list coaches arguments");
+        }
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/ListEngines.java b/src/edu/kit/informatik/ui/command/ListEngines.java
index 9244e3a..80276bb 100644
--- a/src/edu/kit/informatik/ui/command/ListEngines.java
+++ b/src/edu/kit/informatik/ui/command/ListEngines.java
@@ -1,6 +1,9 @@
 package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.LIST_ENGINES;
 
 /**
  * Command used to print a list of engines.
@@ -13,4 +16,14 @@ public class ListEngines extends Command {
     public void apply(final ModelRailwaySimulation simulation) {
         simulation.printEngines();
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(LIST_ENGINES)) {
+            throw new InvalidInputException("unknown command");
+        }
+        if (input.length() > LIST_ENGINES.length()) {
+            throw new InvalidInputException("too many list engines arguments");
+        }
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/ListTracks.java b/src/edu/kit/informatik/ui/command/ListTracks.java
index 32f939a..a2fe4dd 100644
--- a/src/edu/kit/informatik/ui/command/ListTracks.java
+++ b/src/edu/kit/informatik/ui/command/ListTracks.java
@@ -1,6 +1,9 @@
 package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.LIST_TRACKS;
 
 /**
  * Command used to print a list of tracks and switches.
@@ -13,4 +16,14 @@ public class ListTracks extends Command {
     public void apply(final ModelRailwaySimulation simulation) {
         simulation.printTracks();
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(LIST_TRACKS)) {
+            throw new InvalidInputException("unknown command");
+        }
+        if (input.length() > LIST_TRACKS.length()) {
+            throw new InvalidInputException("too many arguments for list tracks");
+        }
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/ListTrainSets.java b/src/edu/kit/informatik/ui/command/ListTrainSets.java
index 202fffd..3689341 100644
--- a/src/edu/kit/informatik/ui/command/ListTrainSets.java
+++ b/src/edu/kit/informatik/ui/command/ListTrainSets.java
@@ -1,6 +1,9 @@
 package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.LIST_TRAIN_SETS;
 
 /**
  * Command used to print a list of train sets on the terminal.
@@ -13,4 +16,14 @@ public class ListTrainSets extends Command {
     public void apply(final ModelRailwaySimulation simulation) {
         simulation.printTrainSets();
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(LIST_TRAIN_SETS)) {
+            throw new InvalidInputException("unknown command");
+        }
+        if (input.length() > LIST_TRAIN_SETS.length()) {
+            throw new InvalidInputException("too many list train-sets arguments");
+        }
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/ListTrains.java b/src/edu/kit/informatik/ui/command/ListTrains.java
index 5a1b0c5..881117c 100644
--- a/src/edu/kit/informatik/ui/command/ListTrains.java
+++ b/src/edu/kit/informatik/ui/command/ListTrains.java
@@ -1,6 +1,9 @@
 package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.LIST_TRAINS;
 
 /**
  * Command used to print a list of trains on the terminal.
@@ -13,4 +16,14 @@ public class ListTrains extends Command {
     public void apply(final ModelRailwaySimulation simulation) {
         simulation.printTrains();
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(LIST_TRAINS)) {
+            throw new InvalidInputException("unknown command");
+        }
+        if (input.length() > LIST_TRAINS.length()) {
+            throw new InvalidInputException("too many list trains arguments");
+        }
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/PutTrain.java b/src/edu/kit/informatik/ui/command/PutTrain.java
index 8a26b79..352d4e7 100644
--- a/src/edu/kit/informatik/ui/command/PutTrain.java
+++ b/src/edu/kit/informatik/ui/command/PutTrain.java
@@ -5,6 +5,13 @@ import edu.kit.informatik.model.Vector2D;
 import edu.kit.informatik.Terminal;
 import edu.kit.informatik.ui.InvalidInputException;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
+import static edu.kit.informatik.ui.command.CommandFactory.PUT_TRAIN;
+import static edu.kit.informatik.ui.command.CommandFactory.VECTOR;
+
 /**
  * Command used to put a train on the rail network.
  *
@@ -12,30 +19,21 @@ import edu.kit.informatik.ui.InvalidInputException;
  * @version 1.0
  */
 public class PutTrain extends Command {
+    private static final Pattern PUT_TRAIN_ARGUMENTS
+            = Pattern.compile(" (" + NUMBER + ") at \\((" + VECTOR + ")\\) in direction (" + VECTOR + ")");
+
     /**
      * Identifier of the train to place.
      */
-    private final int id;
+    private int id;
     /**
      * Where to place the train.
      */
-    private final Vector2D point;
+    private Vector2D point;
     /**
      * Initial direction of the train.
      */
-    private final Vector2D direction;
-
-    /**
-     * Construct a new 'put train' command.
-     * @param id identifier of the train
-     * @param point where to put the train
-     * @param direction initial direction
-     */
-    public PutTrain(final int id, final Vector2D point, final Vector2D direction) {
-        this.id = id;
-        this.point = point;
-        this.direction = direction;
-    }
+    private Vector2D direction;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) throws InvalidInputException {
@@ -45,4 +43,18 @@ public class PutTrain extends Command {
             Terminal.printError("could not place train");
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(PUT_TRAIN)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = PUT_TRAIN_ARGUMENTS.matcher(input.substring(PUT_TRAIN.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid put train arguments");
+        }
+        id = Integer.parseInt(matcher.group(1));
+        point = Vector2D.parse(matcher.group(2));
+        direction = Vector2D.parse(matcher.group(3));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/SetSwitch.java b/src/edu/kit/informatik/ui/command/SetSwitch.java
index e3a78bf..d6910f9 100644
--- a/src/edu/kit/informatik/ui/command/SetSwitch.java
+++ b/src/edu/kit/informatik/ui/command/SetSwitch.java
@@ -3,6 +3,14 @@ package edu.kit.informatik.ui.command;
 import edu.kit.informatik.model.ModelRailwaySimulation;
 import edu.kit.informatik.model.Vector2D;
 import edu.kit.informatik.Terminal;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
+import static edu.kit.informatik.ui.command.CommandFactory.SET_SWITCH;
+import static edu.kit.informatik.ui.command.CommandFactory.VECTOR;
 
 /**
  * Command used to specify the position a switch is set to.
@@ -11,25 +19,17 @@ import edu.kit.informatik.Terminal;
  * @version 1.0
  */
 public class SetSwitch extends Command {
+    private static final Pattern SET_SWITCH_ARGUMENTS
+            = Pattern.compile(" (" + NUMBER + ") position \\((" + VECTOR + ")\\)");
+
     /**
      * Identifier of the switch to configure.
      */
-    private final int id;
+    private int id;
     /**
      * Position to set the switch to.
      */
-    private final Vector2D point;
-
-    /**
-     * Construct a new 'set switch' command.
-     * @param id identifier of the switch
-     * @param point position to set the switch to
-     */
-    public SetSwitch(final int id, final Vector2D point) {
-        this.id = id;
-        // make sure caller can not modify internal state
-        this.point = new Vector2D(point);
-    }
+    private Vector2D point;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) {
@@ -39,4 +39,17 @@ public class SetSwitch extends Command {
             Terminal.printError("could not set switch");
         }
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(SET_SWITCH)) {
+            throw new InvalidInputException("unknown command");
+        }
+        Matcher matcher = SET_SWITCH_ARGUMENTS.matcher(input.substring(SET_SWITCH.length()));
+        if (!matcher.matches()) {
+            throw new InvalidInputException("invalid set switch argument syntax");
+        }
+        id = Integer.parseInt(matcher.group(1));
+        point = Vector2D.parse(matcher.group(2));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/ShowTrain.java b/src/edu/kit/informatik/ui/command/ShowTrain.java
index e26b54a..348e481 100644
--- a/src/edu/kit/informatik/ui/command/ShowTrain.java
+++ b/src/edu/kit/informatik/ui/command/ShowTrain.java
@@ -1,6 +1,10 @@
 package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.NUMBER;
+import static edu.kit.informatik.ui.command.CommandFactory.SHOW_TRAIN;
 
 /**
  * Command used to print a train as ASCII art.
@@ -12,18 +16,22 @@ public class ShowTrain extends Command {
     /**
      * Identifier of the train to display.
      */
-    private final int id;
-
-    /**
-     * Construct a new 'show train' command.
-     * @param id identifier of the train to show
-     */
-    public ShowTrain(final int id) {
-        this.id = id;
-    }
+    private int id;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) {
         simulation.printTrain(id);
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(SHOW_TRAIN)) {
+            throw new InvalidInputException("unknown command");
+        }
+        String argument = input.substring(SHOW_TRAIN.length());
+        if (!argument.matches(" " + NUMBER)) {
+            throw new InvalidInputException("invalid show train argument");
+        }
+        id = Integer.parseInt(argument.substring(1));
+    }
 }
diff --git a/src/edu/kit/informatik/ui/command/Step.java b/src/edu/kit/informatik/ui/command/Step.java
index fee69da..9ac0b61 100644
--- a/src/edu/kit/informatik/ui/command/Step.java
+++ b/src/edu/kit/informatik/ui/command/Step.java
@@ -1,6 +1,9 @@
 package edu.kit.informatik.ui.command;
 
 import edu.kit.informatik.model.ModelRailwaySimulation;
+import edu.kit.informatik.ui.InvalidInputException;
+
+import static edu.kit.informatik.ui.command.CommandFactory.STEP;
 
 /**
  * Command used to advance the simulation.
@@ -12,18 +15,22 @@ public class Step extends Command {
     /**
      * Amount of steps to perform (= speed).
      */
-    private final short speed;
-
-    /**
-     * Construct a new 'step' command.
-     * @param speed the amount of steps to perform, can be any value
-     */
-    public Step(final short speed) {
-        this.speed = speed;
-    }
+    private short speed;
 
     @Override
     public void apply(final ModelRailwaySimulation simulation) {
         simulation.step(speed);
     }
+
+    @Override
+    public void parse(String input) throws InvalidInputException {
+        if (input == null || !input.startsWith(STEP)) {
+            throw new InvalidInputException("unknown command");
+        }
+        String argument = input.substring(STEP.length());
+        if (!argument.matches(" [+-]?\\d+")) {
+            throw new InvalidInputException("invalid step argument");
+        }
+        speed = Short.parseShort(argument.substring(1));
+    }
 }