| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package java.util; |
| |
| /** |
| * The {@code TimerTask} class represents a task to run at a specified time. The task |
| * may be run once or repeatedly. |
| * |
| * @see Timer |
| * @see java.lang.Object#wait(long) |
| */ |
| public abstract class TimerTask implements Runnable { |
| /* Lock object for synchronization. It's also used by Timer class. */ |
| final Object lock = new Object(); |
| |
| /* If timer was cancelled */ |
| boolean cancelled; |
| |
| /* Slots used by Timer */ |
| long when; |
| |
| long period; |
| |
| boolean fixedRate; |
| |
| /* |
| * The time when task will be executed, or the time when task was launched |
| * if this is task in progress. |
| */ |
| private long scheduledTime; |
| |
| /* |
| * Method called from the Timer for synchronized getting of when field. |
| */ |
| long getWhen() { |
| synchronized (lock) { |
| return when; |
| } |
| } |
| |
| /* |
| * Method called from the Timer object when scheduling an event @param time |
| */ |
| void setScheduledTime(long time) { |
| synchronized (lock) { |
| scheduledTime = time; |
| } |
| } |
| |
| /* |
| * Is TimerTask scheduled into any timer? |
| * |
| * @return {@code true} if the timer task is scheduled, {@code false} |
| * otherwise. |
| */ |
| boolean isScheduled() { |
| synchronized (lock) { |
| return when > 0 || scheduledTime > 0; |
| } |
| } |
| |
| /** |
| * Creates a new {@code TimerTask}. |
| */ |
| protected TimerTask() { |
| } |
| |
| /** |
| * Cancels the {@code TimerTask} and removes it from the {@code Timer}'s queue. Generally, it |
| * returns {@code false} if the call did not prevent a {@code TimerTask} from running at |
| * least once. Subsequent calls have no effect. |
| * |
| * @return {@code true} if the call prevented a scheduled execution |
| * from taking place, {@code false} otherwise. |
| */ |
| public boolean cancel() { |
| synchronized (lock) { |
| boolean willRun = !cancelled && when > 0; |
| cancelled = true; |
| return willRun; |
| } |
| } |
| |
| /** |
| * Returns the scheduled execution time. If the task execution is in |
| * progress it returns the execution time of the ongoing task. Tasks which |
| * have not yet run return an undefined value. |
| * |
| * @return the most recent execution time. |
| */ |
| public long scheduledExecutionTime() { |
| synchronized (lock) { |
| return scheduledTime; |
| } |
| } |
| |
| /** |
| * The task to run should be specified in the implementation of the {@code run()} |
| * method. |
| */ |
| public abstract void run(); |
| |
| } |