java中减法和乘法的性能比较

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#1 :32
#2 :-32
#3 :-32
#4 * (-1) running time is：115391

#5 0- running time is：22911

性能约好８０％

在android自定义view的过程中，注意使用。

public class SubMultiplicationPerformanceTest {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        long startTime = 0L;
        long endTime = 0L;
        
        //求相反数
        System.out.println("#1 :"+getScrollDistance());
        System.out.println("#2 :"+getScrollDistance() * (-1));
        System.out.println("#3 :"+(0 - getScrollDistance()));
        
        //乘法
        startTime = System.nanoTime();
        for (int i = 0; i < 1000; i++) {
            int result = getScrollDistance() * (-1);
        }
        endTime = System.nanoTime();
        System.out.println("#4 * (-1) running time is："+(endTime-startTime));
        
        //减法
        startTime = System.nanoTime();
        for (int i = 0; i < 1000; i++) {
            int result = (0 - getScrollDistance());
        }
        endTime = System.nanoTime();
        System.out.println("#5 0- running time is："+(endTime-startTime));

    }
    
    private static int getScrollDistance() {
        return 32;
    }

}