Java中的移位

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Java中的移位，对 int 3 进行移位：
3本身：0000 0000 0000 0000 0000 0000 0000 0011（没疑问）
3<<30: 1100 0000 0000 0000 0000 0000 0000 0000（没疑问）
3<<31: 1000 0000 0000 0000 0000 0000 0000 0000（没疑问）

3<<32: 0000 0000 0000 0000 0000 0000 0000 0011（奇怪啊，最后四位应该是 0000 才对啊）

最后面的问题搞不定，谁能解释下啊

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找到答案了：

Java™ Language Specification, Third Edition -- 15.19. Shift Operators

If the promoted type of the left-hand operand is int, only thefive lowest-order bits of the right-hand operand are used as the shift distance. It is as if the right-hand operand were subjected to a bitwise logical AND operator & (§15.22.1) with the mask value 0x1f. The shift distance actually used is therefore always in the range 0 to 31, inclusive.

If the promoted type of the left-hand operand is long, then only the six lowest-order bits of theright-hand operand are used as the shift distance. It is as if the right-hand operand were subjected to a bitwise logical AND operator & (§15.22.1) with the mask value 0x3f. The shift distance actually used is therefore always in the range 0 to 63, inclusive.