long time1 = System.currentTimeMillis(); int a = 45456485, b = 0; for(int i = 100000; --i >= 0;) { b = a >> 10; } tt1 = System.currentTimeMillis() - time1;//307
time1 = System.currentTimeMillis(); for(int i = 100000; --i >= 0;) { b = a / 1024; } tt2 = System.currentTimeMillis() - time1;//584
time1 = System.currentTimeMillis(); for(int i = 0; i < 100000; i++) { b = a / 1024; } tt3 = System.currentTimeMillis() - time1;//647
time1 = System.currentTimeMillis(); for(int i = 0; i < 100000; i++) { b = a >> 10; } tt4 = System.currentTimeMillis() - time1;//354
System.out.println(String.valueOf(b));
结论: for循环建议写成这样: for(int i = value; --i >= 0;), 可提高效率15%左右 除法时如果是除以2的N次方 建议写成 >> N, 可提高效率90%左右, 乘法同理