java-design-patterns/state/src/main/java/com/iluwatar/Mammoth.java

package com.iluwatar;

/**
 * 
 * Mammoth has internal state that defines its behavior.
 * 
 */
public class Mammoth {

	private State state;

	public Mammoth() {
		state = new PeacefulState(this);
	}

	public void timePasses() {
		if (state.getClass().equals(PeacefulState.class)) {
			changeStateTo(new AngryState(this));
		} else {
			changeStateTo(new PeacefulState(this));
		}
	}

	private void changeStateTo(State newState) {
		this.state = newState;
		this.state.onEnterState();
	}

	@Override
	public String toString() {
		return "The mammoth";
	}

	public void observe() {
		this.state.observe();
	}
}