printf问题拙计

Java code

long str=System.currentTimeMillis();        ...        long end=System.currentTimeMillis();        System.out.printf("run time is %f",(end-str));

提示错误:


[解决办法]
System.out.printf("run time is %f",(end-str));
改成%s
[解决办法]

探讨

System.out.printf("run time is %f",(end-str));
改成%s