怎么可能有ClassCastException异常的instanceof返回true后 [英] How is it possible to have ClassCastException after instanceof returns true

问题描述

我正在从以下code段<一个href=\"http://$c$c.ohloh.net/file?fid=-0F0FCOc_Dgka3ovb86Swu0zffI&cid=OpnM-8VCwHE&s=Pair.java%20Android&browser=Default#L44\"相对=nofollow> Android的Pair.java

I am getting the following code snippet from Android's Pair.java

public boolean equals(Object o) {
    if (o == this) return true;
    if (!(o instanceof Pair)) return false;
    final Pair<F, S> other;
    try {
        other = (Pair<F, S>) o;
    } catch (ClassCastException e) {
        return false;
    }
    return first.equals(other.first) && second.equals(other.second);
}

我想知道，怎么可能有ClassCastException异常，后的instanceof 返回true。

推荐答案

这是不可能的。在code是没有意义的。谁写它可能不明白，˚F和取值在运行时都被擦除，一个 ClassCastException异常可能永远不会发生。

It isn't possible. The code makes no sense. Whoever wrote it probably didn't understand that F and S are erased at runtime so a ClassCastException could never happen.

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