java中Object类中一些方法的练习

类Object是类层次结构的根类。每个类都使用Object类作为超类（extends Object）。所有对象（包括数组）都实现这个类。
成员方法：
public int hashCode();
public final Class getClass();
public String toString();
public boolean equals(Object obj);
protected ovid finalized();
protected Object clone();
代码包括三个类，Student类，Teacher类和StudentDemo类。
Student.java

package cn.day11_Object.test01;

public class Student {
    private String name;
    private int age;
    public Student() {
        // TODO Auto-generated constructor stub
    }
    public Student(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 study(){
        System.out.println("学习.");
    }

    @Override
    public String toString() {
        //重写了toString()方法，可用alt + shift + s 调出source，
        //然后点击Generate toString()方法
        return "Student [name=" + name + ", age=" + age + "]";
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)//两者指向同一个对象
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Student other = (Student) 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;
    }



/*  @Override
    public boolean equals(Object obj) {
        // TODO Auto-generated method stub
        //判断obj是否是此类对象
        if(!(obj instanceof Student)){
            return false;
        }

        Student temp = (Student)obj;

        if (this.name.equals(temp) && this.age == temp.age) {
            return true;
        } else {
            return false;
        }



        //直接返回值
        return this.name.equals(temp.name) && this.age == temp.age;


        if(this.name.equals(temp.name) && this.age == temp.age){
            return true;
        }
        else{
            return false;
        }


//      return super.equals(obj);
    }
    */
}

Teacher.java

package cn.day11_Object.test01;

//导包的快捷键ctrl + shift + o
import java.util.Date;

public class Teacher implements Cloneable{
    private String name;
    private int age;
    private Date time = new Date();
    public Teacher() {
        // TODO Auto-generated constructor stub
    }
    public Teacher(String name, int age, Date time) {
        super();
        this.name = name;
        this.age = age;
        this.time = time;
    }
    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 Date getTime() {
        return time;
    }
    public void setTime(Date time) {
        this.time = time;
    }
    public void teach(){
        System.out.println("老师教学。");
    }

    //重写clone()方法
/*  @Override
    protected Object clone() throws CloneNotSupportedException {
        // TODO Auto-generated method stub
        return super.clone();
    }
    */

    public Object clone(){
        Teacher obj = null;
        try {
            obj = (Teacher)super.clone();
        } catch (CloneNotSupportedException e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        obj.time = (Date)this.getTime().clone();
        return obj;
    }
}

StudentDemo.java

package cn.day11_Object.test01;

import java.util.Date;

public class StudentDemo extends Object{
    public static void main(String[] args) throws CloneNotSupportedException {
        //show1();
        //show2();
        //show3();
        //show4();
        //show5();
        //show6();
        Date b = new Date();
        System.out.println(b);
        show7(b);

    }

    public static void show7(Date b) throws CloneNotSupportedException{
        /**
         * clone()方法，同样存在浅复制和深复制，
         * 当类中只有基本类型的数据时，用浅复制即可，
         * 当存在非基本类型（引用类型）时，必须对非基本类型的属性也调用clone()方法，
         * 这样才能完成深复制.
         * obj.brith = (Date)this.getBrith().clone();
         */

        Teacher t1 = new Teacher("wang", 20, b);
        System.out.println(t1.getName() + "---" + t1.getAge() + "---" + t1.getTime());
        Teacher t2 = (Teacher)t1.clone();
        System.out.println(t2.getName() + "---" + t2.getAge() + "---" + t2.getTime());
    }

    public static void show6(){
        Student s1 = new Student("zhang", 32);
        Student s2 = new Student("wang", 22);
        Student s3 = s1;
        System.out.println("重写了equals()方法");
        System.out.println(s1.equals(s2));
        System.out.println(s1.equals(s3));
        System.out.println("-------------------");
        Teacher t1 = new Teacher();
        System.out.println(s1.equals(t1));
    }

    public static void show5() {
        Student s1 = new Student();
        Student s2 = new Student();
        Student s3 = s1;
        System.out.println("equals()的特点");
        System.out.println("自反性: " + s1.equals(s1));
        System.out.println(s1.equals(s2));
        System.out.println(s1.equals(s3));

    }

    public static void show4(){
        // == 判断基本类型的值是否相等。
        int aValue = 3;
        int bValue = 5;
        int cValue = 3;
        boolean bool = aValue == bValue;
        System.out.println(bool);
        System.out.println(aValue == cValue);
        System.out.println("---------------");
        String s1 = "hello";
        String s2 = "world";
        String s3 = "hello";
        boolean b2 = s1 == s2;
        System.out.println(b2);
        System.out.println(s1==s3);
        System.out.println("---------------");
        //Object类的equals()方法
        //Student s = new Student();

    }

    public static void show3(){
        Student s = new Student();
        //直接调用对象名和调用对象名.toString()效果一样的。
        System.out.println(s);
        System.out.println(s.toString());
    }

    public static void show2(){
        Student s = new Student();
        System.out.println(s.toString());
        System.out.println("---------------");
        System.out.println(s.getClass());
        System.out.println(s.getClass().getName());
        System.out.println("---------------");
        System.out.println(s.hashCode());
        System.out.println(s.getClass().getName() + '@' 
                + Integer.toHexString(s.hashCode()));
    }

    public static void show1(){
        //对Objectde getClass()和getName(),toString()的练习。
        Student s1 = new Student();
        System.out.println(s1.hashCode());
        Student s2 = new Student();
        System.out.println(s2.hashCode());
        Student s3 = s1;
        System.out.println(s3.hashCode());
        System.out.println("-------------------");
        Student s4 = new Student();
        //Class c1 = s4.getClass();
        //String sc1 = c1.getName();
        //System.out.println(sc1);
        System.out.println(s4.hashCode());
        System.out.println("--------------");
        System.out.println(s4.getClass().getName());
        System.out.println("---------------");
        System.out.println(s4.toString());
        System.out.println(s3.toString());
        System.out.println(s2.toString());
        System.out.println(s1.toString());
        System.out.println("----------------");
        System.out.println(s3.getClass().getName());
        System.out.println(s2.getClass().getName());
        System.out.println(s1.equals(s3));
        System.out.println("----");
        System.out.println(s1.equals(s2));
        System.out.println("----------------");
        System.out.println("----------------");
        //重写了toString()方法之后，对象名和对象名.toString()在输出的时候是一样的。
        System.out.println(s1);
        System.out.println(s2);
        System.out.println(s3);
        System.out.println(s4);
    }


}