== 和 equals

== 和 equals

== 对比的是栈中的值，基本数据类型是变量值，引用类型是堆中内存对象的地址

equals: object中默认也是采用==比较，通常会重写

object

pub1ic boolean equa1s(object obj) {
	return (this == obj);
}

String

string
public boo1ean equals(object anobject) {
    if (this == anobject) {
        return true;
    }
    if (anobject instanceof string) {
        string anotherstring = (string)anobject;
        int n = value.1ength;
        if (n == anotherstring. va1ue.length {
            char v1[] = value;
            char v2[] = anotherstring.value;int i = o;
            while (n-- != 0) {
            if (v1[i] != v2[i])
                return false;
                i++;
            }
    		return true;
        }
    }
    return false;
}

上述代码可以看出，String类中被复写的equals()方法其实是比较两个字符串的内容。

public c1ass stringDemo {
    public static void main(String args []) {
        String str1 = "He11o";
        String str2 = new string("He11o");
        String str3 = str2;//引用传递
        System.out.println(str1 == str2); // false
        System.out.println(str1 == str3); // fa1se
        System.out.println(str2 == str3); // true
        System.out.println(str1.equals(str2)); // true
        System.out.println(str1.equals(str3)); // true
        System.out.println(str2.equals(str3)); // true
    }
}