我看了一下TimeUnit和toMillis()方法.

public long toMillis(long paramLong)

{

throw new AbstractMethodError();

}

toMillis()方法除了抛出AbstractMethodError异常之外什么都不做.

那么,toMillis()方法如何将秒,分钟等转换为毫秒？

解决方法:

打开TimeUnit并查看里面的常量……

/**

* Time unit representing one thousandth of a microsecond

*/

NANOSECONDS {

public long toNanos(long d) { return d; }

public long toMicros(long d) { return d/(C1/C0); }

public long toMillis(long d) { return d/(C2/C0); }

public long toSeconds(long d) { return d/(C3/C0); }

public long toMinutes(long d) { return d/(C4/C0); }

public long toHours(long d) { return d/(C5/C0); }

public long toDays(long d) { return d/(C6/C0); }

public long convert(long d, TimeUnit u) { return u.toNanos(d); }

int excessNanos(long d, long m) { return (int)(d - (m*C2)); }

},

/**

* Time unit representing one thousandth of a millisecond

*/

MICROSECONDS {

public long toNanos(long d) { return x(d, C1/C0, MAX/(C1/C0)); }

public long toMicros(long d) { return d; }

public long toMillis(long d) { return d/(C2/C1); }

public long toSeconds(long d) { return d/(C3/C1); }

public long toMinutes(long d) { return d/(C4/C1); }

public long toHours(long d) { return d/(C5/C1); }

public long toDays(long d) { return d/(C6/C1); }

public long convert(long d, TimeUnit u) { return u.toMicros(d); }

int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }

},

正如您将看到的,枚举器TimeUnit中的每个常量

NANOSECONDS,MICROSECONDS等实现匿名方法,使您可以间接访问toMillis(),因此这种方法

public long toMillis(long duration) {

throw new AbstractMethodError();

}

永远不会被您的代码直接访问…

标签：java,timeunit

来源： https://codeday.me/bug/20190715/1465432.html