Statemachine for installation wizard (WIP)

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

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+package com.earth2me.essentials.update.states;
+
+import com.earth2me.essentials.update.WorkListener;
+import org.bukkit.entity.Player;
+
+
+public abstract class AbstractState
+{
+	private transient boolean abortion = false;
+
+	public abstract AbstractState getNextState();
+
+	/**
+	 * Check if we already know the answer, so the user does not have to answer the question.
+	 * 
+	 * @return true, if the answer could be guessed.
+	 */
+	public boolean guessAnswer()
+	{
+		return false;
+	}
+
+	/**
+	 * Ask the user the question.
+	 * @param sender 
+	 */
+	public abstract void askQuestion(Player sender);
+
+	/**
+	 * React on the answer and set internal variables
+	 * @param answer
+	 * @return true, if the answer could be recognized as a valid answer
+	 */
+	public abstract boolean reactOnAnswer(String answer);
+
+	public final AbstractState reactOnAnswer(final Player sender, final String answer)
+	{
+		final String trimmedAnswer = answer.trim();
+		if (trimmedAnswer.equalsIgnoreCase("quit")
+			|| trimmedAnswer.equalsIgnoreCase("bye")
+			|| trimmedAnswer.equalsIgnoreCase("abort"))
+		{
+			abortion = true;
+			return null;
+		}
+		final boolean found = reactOnAnswer(trimmedAnswer);
+		if (found)
+		{
+			return getNextState();
+		}
+		else
+		{
+			sender.sendMessage("Answer not recognized.");
+			return this;
+		}
+	}
+
+	/**
+	 * Do something based on the answer, that the user gave.
+	 */
+	public abstract void doWork(WorkListener workListener);
+
+	public boolean isAbortion()
+	{
+		return abortion;
+	}
+}