hashCode() 方法用于返回字符串的哈希码。
字符串对象的哈希码根据以下公式计算:
s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]
使用 int 算法,这里 s[i] 是字符串的第 i 个字符,n 是字符串的长度,^ 表示求幂。空字符串的哈希值为 0。
public int hashCode()
返回对象的哈希码值。
package com.yiibai; import java.lang.*; public class StringDemo { public static void main(String[] args) { Integer i = new Integer(50); Long l = new Long(50); Float f = new Float(50); Integer i2 = new Integer(0); // hash codes of different objects with same value are always same System.out.println("Hash code of " + i + " is = " + i.hashCode()); System.out.println("Hash code of " + l + " is = " + l.hashCode()); // hash code for float value i.e different from Integer and Long System.out.println("Hash code of " + f + " is = " + f.hashCode()); // hash code value of number zero(0) is zero(0) System.out.println("Hash code of " + i2 + " is = " + i2.hashCode()); String str = "this is yiibai"; // hash code of string str System.out.println("Hash code of string is = " + str.hashCode()); } }
以上程序执行结果为:
Hash code of 50 is = 50 Hash code of 50 is = 50 Hash code of 50.0 is = 1112014848 Hash code of 0 is = 0 Hash code of string is = -1124820283