Object类的应用概述2

三：equals方法

equals用来判断给定的对象是否与当前对象相等

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

如果当前对象与obj相等则返回true

如果当前对象与obj不相等则返回false

equals方法可以被子类重写，从而改变具体算法

实体类：

package com.entity;

public class Employee {
    private String id;
    private String name;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Employee(String id, String name) {
        this.id = id;
        this.name = name;
    }

    public Employee() {
    }

    @Override
    public boolean equals(Object obj) {
        Employee employee = (Employee) obj;
        return this.getId().equals(employee.getId())?true:false;
    }
}

测试类：

package com.test;

import com.entity.Employee;

public class Test3 {
    public static void main(String[] args) {

        Employee employee1 = new Employee("012345","喜羊羊");
        Employee employee2 = new Employee("012345","懒羊羊");
        boolean bool= employee1.equals(employee2);
        System.out.println(bool?"两个对象id是相同的":"两个对象id是不相同的"); //两个对象id是相同的
    }
}

四：getclass方法

getclass方法返回当前对象的运行时类（class）对象

public final native ClassgetClass();

此方法是个终极本地方法，不允许子类进行重写

五.hashCode方法

hashCode方法返回该对象的int类型哈希值

public native int hashCode();

此方法为提高哈希表的性能而支持，通常在非特殊情况下不必要重写此方法

package com.test;

import com.entity.Users;

public class Test4 {
    public static void main(String[] args) {
        Users u0 = new Users("no8888","懒洋洋",8);
        Users u1 = u0;
        System.out.println(u0.equals(u1));//true
        System.out.println(u0.hashCode());//23934342
        System.out.println(u1.hashCode());//23934342
        System.out.println(new Users().hashCode());//22307196

    }
}

六.clone方法

clone方法返回当前对象的一个副本

protected native Object clone() throws CloneNotSupportedException;

被克隆的对象与当前对象不具有同一个引用，但是具有完全相同的对象属性，欲克隆当前对象则当前对象所属类应实现Cloneable接口

实体类：

package com.entity;

public class Employee implements Cloneable{
    private String id;
    private String name;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Employee(String id, String name) {
        this.id = id;
        this.name = name;
    }

    public Employee() {
    }

    @Override
    public boolean equals(Object obj) {
        Employee employee = (Employee) obj;
        return this.getId().equals(employee.getId())?true:false;
    }

    @Override
    public Employee clone() throws CloneNotSupportedException {
        System.out.println("开始克隆对象");
        return (Employee) super.clone();
    }
}

测试类：

package com.test;

import com.entity.Employee;

import java.util.UUID;

public class Test5 {
    public static void main(String[] args) {
        Employee employee = new Employee(UUID.randomUUID().toString(),"喜羊羊");
        try {
            Employee cloneEmp = employee.clone();
            System.out.println("当前对象与克隆对象是否相等"+(employee==cloneEmp));//当前对象与克隆对象是否相等false
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
    }
}