Java tutorial
/* * 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 org.apache.commons.lang3.time; /** * <p> * <code>StopWatch</code> provides a convenient API for timings. * </p> * * <p> * To start the watch, call {@link #start()}. At this point you can: * </p> * <ul> * <li>{@link #split()} the watch to get the time whilst the watch continues in the background. {@link #unsplit()} will * remove the effect of the split. At this point, these three options are available again.</li> * <li>{@link #suspend()} the watch to pause it. {@link #resume()} allows the watch to continue. Any time between the * suspend and resume will not be counted in the total. At this point, these three options are available again.</li> * <li>{@link #stop()} the watch to complete the timing session.</li> * </ul> * * <p> * It is intended that the output methods {@link #toString()} and {@link #getTime()} should only be called after stop, * split or suspend, however a suitable result will be returned at other points. * </p> * * <p> * NOTE: As from v2.1, the methods protect against inappropriate calls. Thus you cannot now call stop before start, * resume before suspend or unsplit before split. * </p> * * <p> * 1. split(), suspend(), or stop() cannot be invoked twice<br> * 2. unsplit() may only be called if the watch has been split()<br> * 3. resume() may only be called if the watch has been suspend()<br> * 4. start() cannot be called twice without calling reset() * </p> * * <p>This class is not thread-safe</p> * * @since 2.0 * @version $Id$ */ public class StopWatch { private static final long NANO_2_MILLIS = 1000000L; /** * Enumeration type which indicates the status of stopwatch. */ private enum State { UNSTARTED { @Override boolean isStarted() { return false; } @Override boolean isStopped() { return true; } @Override boolean isSuspended() { return false; } }, RUNNING { @Override boolean isStarted() { return true; } @Override boolean isStopped() { return false; } @Override boolean isSuspended() { return false; } }, STOPPED { @Override boolean isStarted() { return false; } @Override boolean isStopped() { return true; } @Override boolean isSuspended() { return false; } }, SUSPENDED { @Override boolean isStarted() { return true; } @Override boolean isStopped() { return false; } @Override boolean isSuspended() { return true; } }; /** * <p> * The method is used to find out if the StopWatch is started. A suspended * StopWatch is also started watch. * </p> * @return boolean * If the StopWatch is started. */ abstract boolean isStarted(); /** * <p> * This method is used to find out whether the StopWatch is stopped. The * stopwatch which's not yet started and explicitly stopped stopwatch is * considered as stopped. * </p> * * @return boolean * If the StopWatch is stopped. */ abstract boolean isStopped(); /** * <p> * This method is used to find out whether the StopWatch is suspended. * </p> * * @return boolean * If the StopWatch is suspended. */ abstract boolean isSuspended(); } /** * Enumeration type which indicates the split status of stopwatch. */ private enum SplitState { SPLIT, UNSPLIT } /** * The current running state of the StopWatch. */ private State runningState = State.UNSTARTED; /** * Whether the stopwatch has a split time recorded. */ private SplitState splitState = SplitState.UNSPLIT; /** * The start time. */ private long startTime; /** * The start time in Millis - nanoTime is only for elapsed time so we * need to also store the currentTimeMillis to maintain the old * getStartTime API. */ private long startTimeMillis; /** * The stop time. */ private long stopTime; /** * <p> * Constructor. * </p> */ public StopWatch() { super(); } /** * <p> * Start the stopwatch. * </p> * * <p> * This method starts a new timing session, clearing any previous values. * </p> * * @throws IllegalStateException * if the StopWatch is already running. */ public void start() { if (this.runningState == State.STOPPED) { throw new IllegalStateException("Stopwatch must be reset before being restarted. "); } if (this.runningState != State.UNSTARTED) { throw new IllegalStateException("Stopwatch already started. "); } this.startTime = System.nanoTime(); this.startTimeMillis = System.currentTimeMillis(); this.runningState = State.RUNNING; } /** * <p> * Stop the stopwatch. * </p> * * <p> * This method ends a new timing session, allowing the time to be retrieved. * </p> * * @throws IllegalStateException * if the StopWatch is not running. */ public void stop() { if (this.runningState != State.RUNNING && this.runningState != State.SUSPENDED) { throw new IllegalStateException("Stopwatch is not running. "); } if (this.runningState == State.RUNNING) { this.stopTime = System.nanoTime(); } this.runningState = State.STOPPED; } /** * <p> * Resets the stopwatch. Stops it if need be. * </p> * * <p> * This method clears the internal values to allow the object to be reused. * </p> */ public void reset() { this.runningState = State.UNSTARTED; this.splitState = SplitState.UNSPLIT; } /** * <p> * Split the time. * </p> * * <p> * This method sets the stop time of the watch to allow a time to be extracted. The start time is unaffected, * enabling {@link #unsplit()} to continue the timing from the original start point. * </p> * * @throws IllegalStateException * if the StopWatch is not running. */ public void split() { if (this.runningState != State.RUNNING) { throw new IllegalStateException("Stopwatch is not running. "); } this.stopTime = System.nanoTime(); this.splitState = SplitState.SPLIT; } /** * <p> * Remove a split. * </p> * * <p> * This method clears the stop time. The start time is unaffected, enabling timing from the original start point to * continue. * </p> * * @throws IllegalStateException * if the StopWatch has not been split. */ public void unsplit() { if (this.splitState != SplitState.SPLIT) { throw new IllegalStateException("Stopwatch has not been split. "); } this.splitState = SplitState.UNSPLIT; } /** * <p> * Suspend the stopwatch for later resumption. * </p> * * <p> * This method suspends the watch until it is resumed. The watch will not include time between the suspend and * resume calls in the total time. * </p> * * @throws IllegalStateException * if the StopWatch is not currently running. */ public void suspend() { if (this.runningState != State.RUNNING) { throw new IllegalStateException("Stopwatch must be running to suspend. "); } this.stopTime = System.nanoTime(); this.runningState = State.SUSPENDED; } /** * <p> * Resume the stopwatch after a suspend. * </p> * * <p> * This method resumes the watch after it was suspended. The watch will not include time between the suspend and * resume calls in the total time. * </p> * * @throws IllegalStateException * if the StopWatch has not been suspended. */ public void resume() { if (this.runningState != State.SUSPENDED) { throw new IllegalStateException("Stopwatch must be suspended to resume. "); } this.startTime += System.nanoTime() - this.stopTime; this.runningState = State.RUNNING; } /** * <p> * Get the time on the stopwatch. * </p> * * <p> * This is either the time between the start and the moment this method is called, or the amount of time between * start and stop. * </p> * * @return the time in milliseconds */ public long getTime() { return getNanoTime() / NANO_2_MILLIS; } /** * <p> * Get the time on the stopwatch in nanoseconds. * </p> * * <p> * This is either the time between the start and the moment this method is called, or the amount of time between * start and stop. * </p> * * @return the time in nanoseconds * @since 3.0 */ public long getNanoTime() { if (this.runningState == State.STOPPED || this.runningState == State.SUSPENDED) { return this.stopTime - this.startTime; } else if (this.runningState == State.UNSTARTED) { return 0; } else if (this.runningState == State.RUNNING) { return System.nanoTime() - this.startTime; } throw new RuntimeException("Illegal running state has occurred."); } /** * <p> * Get the split time on the stopwatch. * </p> * * <p> * This is the time between start and latest split. * </p> * * @return the split time in milliseconds * * @throws IllegalStateException * if the StopWatch has not yet been split. * @since 2.1 */ public long getSplitTime() { return getSplitNanoTime() / NANO_2_MILLIS; } /** * <p> * Get the split time on the stopwatch in nanoseconds. * </p> * * <p> * This is the time between start and latest split. * </p> * * @return the split time in nanoseconds * * @throws IllegalStateException * if the StopWatch has not yet been split. * @since 3.0 */ public long getSplitNanoTime() { if (this.splitState != SplitState.SPLIT) { throw new IllegalStateException("Stopwatch must be split to get the split time. "); } return this.stopTime - this.startTime; } /** * Returns the time this stopwatch was started. * * @return the time this stopwatch was started * @throws IllegalStateException * if this StopWatch has not been started * @since 2.4 */ public long getStartTime() { if (this.runningState == State.UNSTARTED) { throw new IllegalStateException("Stopwatch has not been started"); } // System.nanoTime is for elapsed time return this.startTimeMillis; } /** * <p> * Gets a summary of the time that the stopwatch recorded as a string. * </p> * * <p> * The format used is ISO 8601-like, <i>hours</i>:<i>minutes</i>:<i>seconds</i>.<i>milliseconds</i>. * </p> * * @return the time as a String */ @Override public String toString() { return DurationFormatUtils.formatDurationHMS(getTime()); } /** * <p> * Gets a summary of the split time that the stopwatch recorded as a string. * </p> * * <p> * The format used is ISO 8601-like, <i>hours</i>:<i>minutes</i>:<i>seconds</i>.<i>milliseconds</i>. * </p> * * @return the split time as a String * @since 2.1 */ public String toSplitString() { return DurationFormatUtils.formatDurationHMS(getSplitTime()); } /** * <p> * The method is used to find out if the StopWatch is started. A suspended * StopWatch is also started watch. * </p> * * @return boolean * If the StopWatch is started. * @since 3.2 */ public boolean isStarted() { return runningState.isStarted(); } /** * <p> * This method is used to find out whether the StopWatch is suspended. * </p> * * @return boolean * If the StopWatch is suspended. * @since 3.2 */ public boolean isSuspended() { return runningState.isSuspended(); } /** * <p> * This method is used to find out whether the StopWatch is stopped. The * stopwatch which's not yet started and explicitly stopped stopwatch is * considered as stopped. * </p> * * @return boolean * If the StopWatch is stopped. * @since 3.2 */ public boolean isStopped() { return runningState.isStopped(); } }