== :
1.基本数据类型:根据基本数据类型的值判断是否相等,相等返回true,反之返回false
注意:两端数据类型可以不同, 在不同的情况下,也可以返回true
2.引用数据类型:Object obj1 = newObject(); 比较引用类型变量的地址值是否相等
Object obj2= newObject();
system.out.println(obj1 == obj2)//false
TestEquals:
package com.aff.equals;import com.aff.java1.Person;public class TestEquals {
public static void main(String[] args) {
// ==
int i = 12;
int j = 12;
System.out.println(i == j);// true
char c = 12;
System.out.println(i == c);// true
float f = 12.0f;
System.out.println(i == f);// true int k = 65;
char a = 'A';
System.out.println(k == a);// true Object obj1 = new Object();
Object obj2 = new Object();
System.out.println(obj1);
System.out.println(obj2);
System.out.println(obj1 == obj2);// false Person p1 = new Person();
Person p2 = new Person();
Person p3 = p1;
System.out.println(p1 == p2);// false
System.out.println(p1 == p3);// true
System.out.println("---------------------分割线-------------------------"); // equals():①只能处理引用类型变量
// ②在Object类,发现equals()仍然比较的两个引用变量的地址值是否相等
// java.lang.Object类,是所有类的根父类
Person p5 = new Person();
Person p6 = new Person();
System.out.println(p5.equals(p6));// false-->true 重写了Person的equals方法
System.out.println(p5 == p6);// false // 像String 包装类 File类 Date类这些重写Object类的equals()方法,
//比较是两个对象的实体内容是否完全相同
String str1 = new String("AA");
String str2 = new String("AA");
System.out.println(str1 == str2);// false
System.out.println(str1.equals(str2));// true }
}输出结果:
true
true
true
true
java.lang.Object@6d06d69c
java.lang.Object@7852e922
false
false
true
———————分割线————————-
true
false
false
true
Person:重写equals方法:
package com.aff.java1;public class Person {
private String name;
private int age; public Person() {
super();
} public Person(String name, int age) {
super();
this.name = name;
this.age = age;
} public String getName() {
return name;
} public void setName(String name) {
this.name = name;
} public int getAge() {
return age;
} public void setAge(int age) {
this.age = age;
} public void walk() {
System.out.println("走路");
} public void eat() {
System.out.println("吃");
} @Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Person other = (Person) obj;
if (age != other.age)
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}/* public boolean equals(Object obj) {
return true;
}
*/}