java.lang.String.hashCode()方法範例

java.lang.String.hashCode() 方法返回該字串的雜湊碼。對於String物件的雜湊碼的計算方法為：

s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1] 其中，s[i]為字串的第i個字元，n是字串的長度，^表示求冪

宣告

以下是java.lang.String.hashCode()方法的宣告

public int hashCode()

引數

• NA

返回值

此方法返回該物件的雜湊碼值。

異常

• NA

例子

下面的例子顯示java.lang.String.hashCode()方法的使用。

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());
  }
}

讓我們編譯並執行上述程式，這將產生以下結果：

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 = 643938959