measuring execution time in java [duplicate]

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Measure execution time for a开发者_如何学编程 Java method

I would like to test my app, I know there's a certain method in java that returns the execution time but I couldn't find it. Any hints?

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long startTime = new Date().getTime();
doSomething();
long endTime = new Date().getTime();
System.out.println("elapsed milliseconds: " + (endTime - startTime));

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long startTime = System.currentTimeMillis();
//...
long entTime = System.currentTimeMillis();
long spentTime = endTime - startTime;

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long start = System.currentTimeMillis();
//long start = System.nanoTime();
long end = System.currentTimeMillis();
//long end = System.nanoTime();
System.out.println("time diff = " + (end - start) + " ms");

you can use nanoTime() instead of currentTimeMillis() for extra accuracy more discussion about this here

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This should work:

System.currentTimeMillis();

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long start, end, total;

start = System.currentTimeMillis();
// do stuff   
end = System.currentTimeMillis();

total = end - start;

total will contain the time to run through the main section of your code in milliseconds.

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I'm not a Java expert but I don't think there is such function. What can you do is to check the system time before and after the bits of code you with to test.& This is one useful implementation.

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You can get a current snapshot of the system time with System.currentTimeMillis().

If you're looking to generate more complicated performance statistics than just timing a single block of code, I'd take a look at the perf4j library. It provides tools for logging performance stats and generating aggregated statistics like mean, min and max times.