javaObject

Object

1 Object 包 java.lang.Object,是所有类的默认父类

2 里面的方法 toString, equals

public class Object{
    public String toString() {
        return getClass().getName() + "@" + 
            Integer.toHexString(hashCode());
    }
    public boolean equals(Object obj) {
        return (this == obj);
    }


}

如果子类没有覆盖重写toString,equals方法，则使用的是Object类中的方法

3 覆盖重写Object中的方法

import java.util.Objects;

public class Test{
    private int num;
    protected String name;

    public Test() {
    }

    public Test(int num, String name) {
        this.num = num;
        this.name = name;
    }

    public int getNum() {
        return num;
    }

    public void setNum(int num) {
        this.num = num;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Test test = (Test) o;
        return num == test.num &&
                Objects.equals(name, test.name);
    }
    @Override
    public String toString() {
        return "Test{" +
                "num=" + num +
                ", name='" + name + '\'' +
                '}';
    }

    public void method(){

        System.out.println(this.name);
    }
}

4 Objects类的equals方法

public class Objects{
    public static boolean equals(Object o1,Object o2){
        return o1==o2 ||(01!=null && o1.equals(o2));
} 
}