String类型是不可变类理解

布满荆棘的人生 2022-02-02 09:13 207阅读 0赞

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDgwNzI0Nw_size_16_color_FFFFFF_t_70]  
Object的hashCode()默认是返回内存地址的，但是hashCode()可以重写，所以hashCode()不能代表内存地址的不同

System.identityHashCode(Object)方法可以返回对象的内存地址,不管该对象的类是否重写了hashCode()方法。

package com.question;
    
    /**
     * @author kankan
     * @creater 2019-05-11 7:33
     */
    public class Example {
        String str = new String("tarena");
        char[] ch = {'a','b','c'};
    
        public static void main(String[] args) {
            Example ex = new Example();
            ex.change(ex.str,ex.ch);
            System.out.println(ex.str);
            System.out.println("ex.str " + System.identityHashCode(ex.str));
            System.out.println(ex.ch);
            System.out.println("ex.ch " + System.identityHashCode(ex.ch));
        }
    
        private void change(String str, char[] ch) {
            str = "test ok";
            ch[0] = 'g';
            System.out.println("str " + System.identityHashCode(str));
            System.out.println("ch " + System.identityHashCode(ch));
        }
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDgwNzI0Nw_size_16_color_FFFFFF_t_70 1]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDgwNzI0Nw_size_16_color_FFFFFF_t_70 1]: /images/20220202/bc4b26b138e04516914710c90bc1d8f1.png