== 与 equlas

1. ==

　　1.1 基本数据类型比较值

　　1.2 引用数据类型比较引用地址

　　

public class EqualsTest {
    public static void main(String[] args) {
        Person tom = new Person(1, "Tom");
        Person tom1 = new Person(1, "Tom");
        System.out.println(tom == tom1);
        System.out.println(1 == 1);
    }
}

结果：

false
true

2. equlas

　　2.1 equlas 中的源代码

　　object:

public boolean equals(Object obj) {
        return (this == obj);
}

　　Integer:

public boolean equals(Object obj) {
    if (obj instanceof Integer) {
        return value == ((Integer)obj).intValue();
    }
    return false;
}

　　String:

    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;
    }

　　2.2 代码实战

　　

public class EqualsTest {
    public static void main(String[] args) {
        Person tom = new Person(1, "Tom");
        Person tom1 = new Person(1, "Tom");
        System.out.println(tom.equals(tom1));
        Integer a = 1;
        System.out.println(a.equals(1));
        String s = "Tom";
        System.out.println(s.equals("Tom"));
    }
}

 

结果：

false
true
true

 

 

 

public class EqualsTest {
    public static void main(String[] args) {
        Person tom = new Person(1, "Tom");
Person tom1 = new Person(1, "Tom");
System.out.println(tom.equals(tom1));
}
}