Moving the link between the states from the constructor of the state machine to the states classes.

EssentialsUpdate/src/com/earth2me/essentials/update/states/AbstractState.java

@@ -7,6 +7,17 @@ import org.bukkit.entity.Player;
 public abstract class AbstractState
 {
 	private transient boolean abortion = false;
+	private final transient StateMap stateMap;
+
+	public AbstractState(final StateMap stateMap)
+	{
+		this.stateMap = stateMap;
+	}
+
+	public AbstractState getState(final Class<? extends AbstractState> stateClass)
+	{
+		return stateMap.get(stateClass);
+	}
 
 	public abstract AbstractState getNextState();
 
@@ -40,7 +51,7 @@ public abstract class AbstractState
 			|| trimmedAnswer.equalsIgnoreCase("bye")
 			|| trimmedAnswer.equalsIgnoreCase("abort"))
 		{
-			abortion = true;
+			abort();
 			return null;
 		}
 		final boolean found = reactOnAnswer(trimmedAnswer);
@@ -64,4 +75,9 @@ public abstract class AbstractState
 	{
 		return abortion;
 	}
+
+	protected void abort()
+	{
+		abortion = true;
+	}
 }

EssentialsUpdate/src/com/earth2me/essentials/update/states/AbstractYesNoState.java

@@ -4,11 +4,17 @@ package com.earth2me.essentials.update.states;
 public abstract class AbstractYesNoState extends AbstractState
 {
 	private boolean answer = false;
-	private final transient AbstractState yesState;
+	private final transient Class<? extends AbstractState> yesState;
-	private final transient AbstractState noState;
+	private final transient Class<? extends AbstractState> noState;
 
-	public AbstractYesNoState(final AbstractState yesState, final AbstractState noState)
+	public AbstractYesNoState(final StateMap states, final Class<? extends AbstractState> nextState)
 	{
+		this(states, nextState, nextState);
+	}
+
+	public AbstractYesNoState(final StateMap states, final Class<? extends AbstractState> yesState, final Class<? extends AbstractState> noState)
+	{
+		super(states);
 		this.yesState = yesState;
 		this.noState = noState;
 	}
@@ -16,7 +22,9 @@ public abstract class AbstractYesNoState extends AbstractState
 	@Override
 	public AbstractState getNextState()
 	{
-		return answer ? yesState : noState;
+		return answer
+			   ? (yesState == null ? null : getState(yesState))
+			   : (noState == null ? null : getState(noState));
 	}
 
 	@Override

EssentialsUpdate/src/com/earth2me/essentials/update/states/EssentialsChat.java

@@ -1,7 +1,7 @@
 package com.earth2me.essentials.update.states;
 
 import com.earth2me.essentials.update.WorkListener;
-import com.earth2me.essentials.update.tasks.InstallChat;
+import com.earth2me.essentials.update.tasks.InstallModule;
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.plugin.Plugin;
@@ -9,9 +9,9 @@ import org.bukkit.plugin.Plugin;
 
 public class EssentialsChat extends AbstractYesNoState
 {
-	public EssentialsChat(final AbstractState next)
+	public EssentialsChat(final StateMap states)
 	{
-		super(next, next);
+		super(states, EssentialsProtect.class);
 	}
 
 	@Override
@@ -38,7 +38,7 @@ public class EssentialsChat extends AbstractYesNoState
 	{
 		if (getAnswer())
 		{
-			new InstallChat(listener).start();
+			new InstallModule(listener, "EssentialsChat").start();
 			return;
 		}
 		listener.onWorkDone();

EssentialsUpdate/src/com/earth2me/essentials/update/states/EssentialsProtect.java

@@ -0,0 +1,46 @@
+package com.earth2me.essentials.update.states;
+
+import com.earth2me.essentials.update.WorkListener;
+import com.earth2me.essentials.update.tasks.InstallModule;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.Player;
+import org.bukkit.plugin.Plugin;
+
+
+public class EssentialsProtect extends AbstractYesNoState
+{
+	public EssentialsProtect(final StateMap states)
+	{
+		super(states, null);
+	}
+
+	@Override
+	public boolean guessAnswer()
+	{
+		final Plugin plugin = Bukkit.getPluginManager().getPlugin("EssentialsProtect");
+		if (plugin != null)
+		{
+			setAnswer(true);
+			return true;
+		}
+		return false;
+	}
+
+	@Override
+	public void askQuestion(final Player sender)
+	{
+		sender.sendMessage("Do you want to install EssentialsProtect? (yes/no)");
+		sender.sendMessage("Short descriptive text about what EssentialsProtect does.");
+	}
+
+	@Override
+	public void doWork(final WorkListener listener)
+	{
+		if (getAnswer())
+		{
+			new InstallModule(listener, "EssentialsProtect").start();
+			return;
+		}
+		listener.onWorkDone();
+	}
+}

EssentialsUpdate/src/com/earth2me/essentials/update/states/StateMachine.java

@@ -2,8 +2,6 @@ package com.earth2me.essentials.update.states;
 
 import com.earth2me.essentials.update.WorkListener;
 import com.earth2me.essentials.update.VersionInfo;
-import java.util.ArrayList;
-import java.util.List;
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.plugin.Plugin;
@@ -15,7 +13,7 @@ public class StateMachine extends WorkListener
 	{
 		ABORT, WAIT, DONE
 	}
-	private final transient List<AbstractState> states = new ArrayList<AbstractState>();
+	private final transient StateMap states = new StateMap();
 	private transient AbstractState current;
 	private final transient Player player;
 
@@ -24,9 +22,8 @@ public class StateMachine extends WorkListener
 		super(plugin, newVersionInfo);
 		this.player = player;
 		states.clear();
-		final AbstractState state = new EssentialsChat(null);
+		states.put(EssentialsChat.class, new EssentialsChat(states));
-		states.add(state);
+		current = states.get(0);
-		current = state;
 	}
 
 	public MachineResult askQuestion()

EssentialsUpdate/src/com/earth2me/essentials/update/states/StateMap.java

@@ -0,0 +1,12 @@
+package com.earth2me.essentials.update.states;
+
+import java.util.LinkedHashMap;
+
+
+public class StateMap extends LinkedHashMap<Class<? extends AbstractState>, AbstractState>
+{
+	public StateMap()
+	{
+		super();
+	}
+}

EssentialsUpdate/src/com/earth2me/essentials/update/tasks/InstallChat.java

@@ -1,12 +0,0 @@
-package com.earth2me.essentials.update.tasks;
-
-import com.earth2me.essentials.update.WorkListener;
-
-
-public class InstallChat extends InstallModule
-{
-	public InstallChat(final WorkListener listener)
-	{
-		super(listener, "EssentialsChat");
-	}
-}