1 /* 2 * Copyright (C) 2015 DroidDriver committers 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package io.appium.droiddriver.helpers; 18 19 import java.util.concurrent.atomic.AtomicBoolean; 20 21 /** 22 * Base class for an action that should run only once no matter how many times the method {@link 23 * #singleRun()} is called upon an instance. Typically it is used on a singleton to achieve once for 24 * a class effect. 25 */ 26 public abstract class SingleRun { 27 private final AtomicBoolean hasRun = new AtomicBoolean(); 28 29 /** 30 * Calls {@link #run()} if it is the first time this method is called upon this instance. 31 * 32 * @return true if this is the first time it is called, otherwise false 33 */ singleRun()34 public final boolean singleRun() { 35 if (hasRun.compareAndSet(false, true)) { 36 run(); 37 return true; 38 } 39 return false; 40 } 41 42 /** 43 * Takes the action that should run only once. 44 */ run()45 protected abstract void run(); 46 } 47