今天脑筋有点搭牢，想了半天才看出为什么以下两段代码效果是相同的。。。
第一种好处是可以直接批量复制黏贴system.out, 不用改什么东西
private static long i;
private volatile static long
vt;
private static final int TEST_SIZE = 10000000;
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long time = System.nanoTime();for (int n = 0; n < TEST_SIZE; n++) vt = System.currentTimeMillis();System.out.println(-time + (time = System.nanoTime()));<br>for (int n = 0; n < TEST_SIZE; n++) i = System.currentTimeMillis();System.out.println(-time + (time = System.nanoTime())); |
这种每次要在循环头上重置nanoTime
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<span>private
static long i;</span><br><span>private
volatile static long vt;</span><br><span>private
static final int TEST_SIZE = 10000000;</span><br><br>long
time = System.nanoTime();for (int n = 0; n < TEST_SIZE; n++) { vt = System.currentTimeMillis();}System.out.println((System.nanoTime() - time));time = System.nanoTime();for (int n = 0; n < TEST_SIZE; n++) { i = System.currentTimeMillis();}System.out.println((System.nanoTime() - time)); |
nanoTime对volatile 测试的一种写法,布布扣,bubuko.com
原文：http://www.cnblogs.com/zhukunrong/p/3730106.html