性能测试 1<<-1

public class test {
	public static void main(String[] args) throws ParseException{
		int i = 1;
		//整数的上限
		int j_MAX = 2147483647;
		//负数
		int j_MIN = -1;
		System.out.println(Integer.toBinaryString(j_MIN));  //这个溢出  自动转型成LONG了 
		System.out.println(j_MAX);                          //正常来说位移位数相同
		System.out.println(Integer.toBinaryString(j_MAX));
		double start=System.currentTimeMillis();
		long times = 99999999;
		int k;
		while((times--)>0){
			k = i<<j_MAX;
		} 
		System.out.println("MAX耗时"+(System.currentTimeMillis()-start));
		//System.out.println(k);
		times = 99999999;
		start=System.currentTimeMillis();
		while((times--)>0){
			k = i<<j_MIN;
		}
		System.out.println("MIN耗时"+(System.currentTimeMillis()-start));
		//System.out.println(k);
	}
}

结论 -1在大规模递归运算性能会成阶梯形上升