1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 * 19 */ 20 package org.apache.mina.statemachine.transition; 21 22 import org.apache.mina.statemachine.State; 23 import org.apache.mina.statemachine.StateMachine; 24 import org.apache.mina.statemachine.event.Event; 25 26 /** 27 * The interface implemented by classes which need to react on transitions 28 * between states. 29 * 30 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 31 */ 32 public interface Transition { 33 /** 34 * Executes this {@link Transition}. It is the responsibility of this 35 * {@link Transition} to determine whether it actually applies for the 36 * specified {@link Event}. If this {@link Transition} doesn't apply 37 * nothing should be executed and <code>false</code> must be returned. 38 * 39 * @param event the current {@link Event}. 40 * @return <code>true</code> if the {@link Transition} was executed, 41 * <code>false</code> otherwise. 42 */ 43 boolean execute(Event event); 44 45 /** 46 * Returns the {@link State} which the {@link StateMachine} should move to 47 * if this {@link Transition} is taken and {@link #execute(Event)} returns 48 * <code>true</code>. 49 * 50 * @return the next {@link State} or <code>null</code> if this 51 * {@link Transition} is a loopback {@link Transition}. 52 */ 53 State getNextState(); 54 }