Java Object类equals方法

package com.example.demo.test;

public class Person {

    private String userName;
    private String age;

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }
}

package com.example.demo.test;

public class Test {

    public static void main(String[] args) {
        Person p1 = new Person();
        Person p2 = new Person();
        System.out.println(p1.equals(p2));
        System.out.println(p1 == p2);

        
        String s1 = new String("AA");
        String s2 = new String("AA");
        System.out.println(s1.equals(s2));
        System.out.println(s1 == s2);
    }
}

public boolean equals(Object anObject) {
        if (this == anObject) {
            return true;
        }
        if (anObject instanceof String) {
            String anotherString = (String)anObject;
            int n = value.length;
            if (n == anotherString.value.length) {
                char v1[] = value;
                char v2[] = anotherString.value;
                int i = 0;
                while (n-- != 0) {
                    if (v1[i] != v2[i])
                        return false;
                    i++;
                }
                return true;
            }
        }
        return false;
    }