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    <p>You need to get a <a href="http://java-source.net/open-source/profilers" rel="nofollow">Java profiler</a>. <a href="http://www.eclipse.org/articles/Article-TPTP-Profiling-Tool/tptpProfilingArticle.html" rel="nofollow">Some of them integrate well in Eclipse</a>.</p> <p>Other than that, you're left with using a custom profiler class (if you don't have a lot of profiling to do and if you already suspect some bottlenecks). </p> <p>Here is a simple class to do that:</p> <pre><code>/** * Small helper class to profile the code, take timing, ... * * To use this, simply call the start method with an identifier. When you want to measure the time, call the stop method * with the same identifier. To output statistics, simply call the toString method or the toCsv method to create a CSV * file with the profiler information. * * @author Vincent Prat @ MarvinLabs */ public class Profiler { private static final int THEORETICAL_MAX_NAME_LENGTH = 50; private static Profiler singletonInstance = null; private Map&lt;String, Profile&gt; profiles; // Fast access to profiles by name private List&lt;Profile&gt; profilesStack; // Profiles as created chronologically /** * Get access to the singleton instance (create it if necessary) */ public static Profiler getInstance() { if (singletonInstance == null) { singletonInstance = new Profiler(); } return singletonInstance; } /** * Protected constructor for singleton */ protected Profiler() { profiles = new HashMap&lt;String, Profiler.Profile&gt;(); profilesStack = new ArrayList&lt;Profile&gt;(); } /** * Start a profile. If the profile does not exist, it will be created. If it exists, a new round of measure is * taken. * * @param name * The name of the profile. If possible, less than Profiler.THEORETICAL_MAX_NAME_LENGTH characters * * @see Profiler.THEORETICAL_MAX_NAME_LENGTH */ public void start(String name) { Profile p = profiles.get(name); if (p == null) { p = new Profile(name); profiles.put(name, p); profilesStack.add(p); } p.start(); } /** * Stop a profile and compute some statistics about it. * * @param name * The name of the profile as declared in the corresponding start method */ public void stop(String name) { Profile p = profiles.get(name); if (p == null) { throw new RuntimeException("The profile " + name + " has not been created by a call to the start() method!"); } p.stop(); } /** * Clear all the current measures. Not to be called within any start/stop pair. */ public void reset() { profiles.clear(); } /** * Build a string containing all the information about the measures we have taken so far. */ @Override public String toString() { final StringBuffer sb = new StringBuffer(); for (Profile p : profilesStack) { sb.append(p.toString()); sb.append("\n"); } return sb.toString(); } /** * Output the measures to an output string */ public void toCsvFile(OutputStream os) throws IOException { Profile.writeCsvHeader(os); for (Profile p : profilesStack) { p.writeCsvLine(os); } } /** * Profile information. It stores statistics per named profile. * * @author Vincent Prat @ MarvinLabs */ private static class Profile { private static final String CSV_HEADERS = "Name, Call Count, Total Time (ms), Average Time (ms), Min Time (ms), Max Time (ms), Delta Time (ms), Delta Ratio (%)\n"; private static final String FORMAT_STRING = "%-" + THEORETICAL_MAX_NAME_LENGTH + "." + THEORETICAL_MAX_NAME_LENGTH + "s: %3d calls, total %5d ms, avg %5d ms, min %5d ms, max %5d ms, delta %5d ms (%d%%)"; private static final String CSV_FORMAT_STRING = "%s,%d,%d,%d,%d,%d,%d,%d\n"; private String name; private long startTime; private long callCount; private long totalTime; private long minTime; private long maxTime; public Profile(String name) { this.name = name; this.callCount = 0; this.totalTime = 0; this.startTime = 0; this.minTime = Long.MAX_VALUE; this.maxTime = Long.MIN_VALUE; } public void start() { startTime = System.currentTimeMillis(); } public void stop() { final long elapsed = (System.currentTimeMillis() - startTime); if (elapsed &lt; minTime) minTime = elapsed; if (elapsed &gt; maxTime) maxTime = elapsed; totalTime += elapsed; callCount++; } private String getFormattedStats(String format) { final long avgTime = callCount == 0 ? 0 : (long) totalTime / callCount; final long delta = maxTime - minTime; final double deltaRatio = avgTime == 0 ? 0 : 100.0 * ((double) 0.5 * delta / (double) avgTime); return String .format(format, name, callCount, totalTime, avgTime, minTime, maxTime, delta, (int) deltaRatio); } @Override public String toString() { return getFormattedStats(FORMAT_STRING); } public static void writeCsvHeader(OutputStream os) throws IOException { os.write(CSV_HEADERS.getBytes()); } public void writeCsvLine(OutputStream os) throws IOException { os.write(getFormattedStats(CSV_FORMAT_STRING).getBytes()); } } } </code></pre> <p>And sample usage:</p> <pre><code>Profiler.getInstance().start("marker1"); // Do something... Profiler.getInstance().start("marker2"); // Something else... Profiler.getInstance().stop("marker2"); // And some more... Profiler.getInstance().stop("marker1"); // Output the profiling result System.out.println(Profiler.getInstance().toString()); </code></pre>
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    1. POHow do I analyze which method consumed more time in java,eclipse,junit?
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    1. USVincent Mimoun-Prat
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    1. COThis class also has the critical flaw that it relies on measuring the chronological time by using the system clock, not the actual CPU time consumed by the measured process. When there is any background process which gets CPU time while the method is executed, it will affect the result.
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    2. COThis class has pros and cons indeed, it is meant to be simple to use. As long as you are aware of them and the profiling to do is pretty simple, it should give you a rough idea of where you are spending time. In my case, I use it for some basic profiling of Android applications while developing.
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