Java——object类

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java.lang. 里面的类不用导入包

Object类的成员方法:

public int hashCode();

//就是通过该类在堆上的地址，通过hash算法，算出一个数

public final Class getClass();

//大写 Class 是一种类型；//返回该类的具体类型

public String toString();

public boolean equals(Object obj);

protected void finalize();

protected Object clone();

Student.java

MyObjectDemo.java

package com.java.objectdemo;

//类不写默认的是继承Object类

public class Student implements Cloneable{ //这种没有任何成员或者抽象方法的接口，被称为标记接口

String name;

int age;

boolean gender;

public Student(){

}

public boolean equals(Object obj) {

Student stu=(Student) obj;

if(this.name!=null&&stu.name!=null){

if(this.name.equals(stu.name)&&this.age==stu.age&&this.gender==stu.gender )

return true;

}

return false;

}

//protected void finalize() {} //和c++的析构函数两回事

//当垃圾回收器确定不存在对该对象的更多引用时，由对象的垃圾回收器调用此方法。

public Student(String name,int age,boolean gender){

this.name=name;

this.age=age;

this.gender=gender;

}

public Object clone() throws CloneNotSupportedException{

return super.clone();

}

public String toString() {

return "Student [name=" + name + ", age=" + age + ", gender=" + gender + "]";

}

package com.java.objectdemo;

public class MyObjectDemo {

public static void main(String[] args) {

Student student=new Student();

System.out .println(student.toString()); //对象的字符串表示，建议重写

//默认这里会输出：com.java.objectdemo.Student@15db9742

System.out.println(student); //当我们使用一个对象引用直接输出的时候，系统默认是调用该类的 toString 方法，如果该类没有这个方法就直接调用基类Object的toString方法

//com.java.objectdemo.Student@15db9742

Student student1=new Student("meihao",24,true);

System.out.println( "student1= "+student1);

//student1= com.java.objectdemo.Student@6d06d69c

//这里调用toString方法返回 getClass().getName() + '@' + Integer.toHexString(hashCode())

System.out.println(student.hashCode()); //366712642

Student student2=new Student();

System.out.println(student2.hashCode()); //2018699554

System.out.println(student2.getClass()); //class com.java.objectdemo.Student

Class oClass; //Class 是一个类，该类是用来代表一个student.class 字节码文件对象

System.out.println("(student1==student2) = "+(student1==student2));

//(student1==student2) = false

//调用equals方法，比较的是地址值是不是一样的；this==object ?

System.out.println("(student1.equals(student2)) = "+(student1.equals(student2))); //(student1.equals(student2)) = false

Student stu1=new Student("qw",20,true);

Student stu2=new Student("qw",20,true);

System.out.println("(stu1==stu2) = "+(stu1==stu2));

//(stu1==stu2) = false

System.out.println("(stu1==stu2) = "+(stu1.equals(stu2)));

//(stu1==stu2) = true

Student st1=new Student("张三",18,true);

Student st2=new Student("张三丰",108,true);

try{

Student st3=(Student)st2.clone(); //创建并返回对象的一个副本；深拷贝，新建一个相同内容对象

Student st4=st2; //浅拷贝，只是多了一个链接

}catch(CloneNotSupportedException e){

e.printStackTrace();

}

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Java——object类

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