Mega Code Archive

StopWatch provides a convenient API for timings

import java.util.Date; /* * 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. */ /** * * <code>StopWatch</code> provides a convenient API for timings. * * * * To start the watch, call {@link #start()}. At this point you can: * * <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> * * * 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. * * * * 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. * * * * 1. split(), suspend(), or stop() cannot be invoked twice * 2. unsplit() may only be called if the watch has been split() * 3. resume() may only be called if the watch has been suspend() * 4. start() cannot be called twice without calling reset() * * * @author Stephen Colebourne * @since 2.0 * @version $Id: StopWatch.java 583608 2007-10-10 20:38:41Z ggregory $ */ public class StopWatch { // running states private static final int STATE_UNSTARTED = 0; private static final int STATE_RUNNING = 1; private static final int STATE_STOPPED = 2; private static final int STATE_SUSPENDED = 3; // split state private static final int STATE_UNSPLIT = 10; private static final int STATE_SPLIT = 11; /** * The current running state of the StopWatch. */ private int runningState = STATE_UNSTARTED; /** * Whether the stopwatch has a split time recorded. */ private int splitState = STATE_UNSPLIT; /** * The start time. */ private long startTime = -1; /** * The stop time. */ private long stopTime = -1; /** * * Constructor. * */ public StopWatch() { super(); } /** * * Start the stopwatch. * * * * This method starts a new timing session, clearing any previous values. * * * @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.stopTime = -1; this.startTime = System.currentTimeMillis(); this.runningState = STATE_RUNNING; } /** * * Stop the stopwatch. * * * * This method ends a new timing session, allowing the time to be retrieved. * * * @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.currentTimeMillis(); } this.runningState = STATE_STOPPED; } /** * * Resets the stopwatch. Stops it if need be. * * * * This method clears the internal values to allow the object to be reused. * */ public void reset() { this.runningState = STATE_UNSTARTED; this.splitState = STATE_UNSPLIT; this.startTime = -1; this.stopTime = -1; } /** * * Split the time. * * * * 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. * * * @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.currentTimeMillis(); this.splitState = STATE_SPLIT; } /** * * Remove a split. * * * * This method clears the stop time. The start time is unaffected, enabling timing from the original start point to * continue. * * * @throws IllegalStateException * if the StopWatch has not been split. */ public void unsplit() { if (this.splitState != STATE_SPLIT) { throw new IllegalStateException("Stopwatch has not been split. "); } this.stopTime = -1; this.splitState = STATE_UNSPLIT; } /** * * Suspend the stopwatch for later resumption. * * * * 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. * * * @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.currentTimeMillis(); this.runningState = STATE_SUSPENDED; } /** * * Resume the stopwatch after a suspend. * * * * 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. * * * @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.currentTimeMillis() - this.stopTime); this.stopTime = -1; this.runningState = STATE_RUNNING; } /** * * Get the time on the stopwatch. * * * * This is either the time between the start and the moment this method is called, or the amount of time between * start and stop. * * * @return the time in milliseconds */ public long getTime() { 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.currentTimeMillis() - this.startTime; } throw new RuntimeException("Illegal running state has occured. "); } /** * * Get the split time on the stopwatch. * * * * This is the time between start and latest split. * * * @return the split time in milliseconds * * @throws IllegalStateException * if the StopWatch has not yet been split. * @since 2.1 */ public long getSplitTime() { if (this.splitState != STATE_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"); } return this.startTime; } /** * * Gets a summary of the time that the stopwatch recorded as a string. * * * * The format used is ISO8601-like, hours:minutes:seconds.milliseconds. * * * @return the time as a String */ public String toString() { return new Date(getTime()).toString(); } /** * * Gets a summary of the split time that the stopwatch recorded as a string. * * * * The format used is ISO8601-like, hours:minutes:seconds.milliseconds. * * * @return the split time as a String * @since 2.1 */ public String toSplitString() { return new Date(getSplitTime()).toString(); } }