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降龙 2011-06-20
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[Quote=引用 3 楼 ticmy 的回复:]
According to Joshua Bloch's Effective Java (a book that can't be recommended enough, and which I bought thanks to continual mentions on stackoverflow):
The value 31 was chosen because it is a……
[/Quote]
学习了。。。。
According to Joshua Bloch's Effective Java (a book that can't be recommended enough, and which I bought thanks to continual mentions on stackoverflow):
The value 31 was chosen because it is a……
[/Quote]
学习了。。。。
易德军 2011-06-20
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[Quote=引用 2 楼 ticmy 的回复:]
可能是数学家经过分析计算的，这个数可以让哈希更分散（个人想法）
[/Quote]
我确实也在《Effective Java 2》上看到，如此的说法
可能是数学家经过分析计算的，这个数可以让哈希更分散（个人想法）
[/Quote]
我确实也在《Effective Java 2》上看到，如此的说法
JavaMan_KA 2011-06-20
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[Quote=引用 3 楼 ticmy 的回复:]
According to Joshua Bloch's Effective Java (a book that can't be recommended enough, and which I bought thanks to continual mentions on stackoverflow):
The value 31 was chosen because it is an o……
[/Quote]学习了。
According to Joshua Bloch's Effective Java (a book that can't be recommended enough, and which I bought thanks to continual mentions on stackoverflow):
The value 31 was chosen because it is an o……
[/Quote]学习了。
eclipse_xu 2011-06-19
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还有29
+1
+1
dreamhunter_lan 2011-06-17
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其实也可以是17这样的数~~~只要你喜欢
乀Lan 2011-06-17
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应该是个人需要吧。。我在看老师写的代码的时候乘以1000
他说只要方便 怎么乘都行，
乘以31也是java的“潜规则”,就像创建类时候第一个字母要大写一样。
他说只要方便 怎么乘都行，
乘以31也是java的“潜规则”,就像创建类时候第一个字母要大写一样。
zqfddqr 2011-06-17
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楼主是细心人啊哈哈哈
zqfddqr 2011-06-17
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[Quote=引用 3 楼 ticmy 的回复:]
According to Joshua Bloch's Effective Java (a book that can't be recommended enough, and which I bought thanks to continual mentions on stackoverflow):
The value 31 was chosen because it is an……
[/Quote]还有这说学习了
According to Joshua Bloch's Effective Java (a book that can't be recommended enough, and which I bought thanks to continual mentions on stackoverflow):
The value 31 was chosen because it is an……
[/Quote]还有这说学习了
龙四 2011-06-17
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According to Joshua Bloch's Effective Java (a book that can't be recommended enough, and which I bought thanks to continual mentions on stackoverflow):
The value 31 was chosen because it is an odd prime. If it were even and the multiplication overflowed, information would be lost, as multiplication by 2 is equivalent to shifting. The advantage of using a prime is less clear, but it is traditional. A nice property of 31 is that the multiplication can be replaced by a shift and a subtraction for better performance: 31 * i == (i << 5) - i. Modern VMs do this sort of optimization automatically.
The value 31 was chosen because it is an odd prime. If it were even and the multiplication overflowed, information would be lost, as multiplication by 2 is equivalent to shifting. The advantage of using a prime is less clear, but it is traditional. A nice property of 31 is that the multiplication can be replaced by a shift and a subtraction for better performance: 31 * i == (i << 5) - i. Modern VMs do this sort of optimization automatically.
龙四 2011-06-17
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可能是数学家经过分析计算的，这个数可以让哈希更分散（个人想法）
chenchenyangll 2011-06-17
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13 31 131 331 1313 这些数字都可以
个人认为，选这些数字仅仅是因为这样的hash算法更分散、效果更好
个人认为，选这些数字仅仅是因为这样的hash算法更分散、效果更好
