Day 15 Objectapi作业

作业：完成对FirstLevel对象的深度克隆。

class FirstLevel implements Cloneable {
    int firstIntValue;
    double firstDoubleValue;
    SecondLevel second;

    public FirstLevel(int firstIntValue, double firstDoubleValue, SecondLevel second) {
        this.firstIntValue = firstIntValue;
        this.firstDoubleValue = firstDoubleValue;
        this.second = second;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        // 利用Object的Clone方法，
        FirstLevel first = (FirstLevel) super.clone();

        // 修改 first对象中引用类型成员变量，比如 second 成员变量引用，指向被复制的那个FirstLevel对象的second对象的拷贝，

        return first;
    }

    public void testProtected() throws CloneNotSupportedException {
        // 跨包子类访问父类 ，访问FirstLevel自己从Object继承下来的Clone方法
        clone(); // alt + enter

        FirstLevel firstLevel = new FirstLevel(10, 20);
        firstLevel.clone();
    }
}

class SecondLevel implements Cloneable {
    int secondIntValue;
    double secondDoubleValue;
    ThirdLevel third;

    public SecondLevel(int secondIntValue, double secondDoubleValue, ThirdLevel third) {
        this.secondIntValue = secondIntValue;
        this.secondDoubleValue = secondDoubleValue;
        this.third = third;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        SecondLevel clone = (SecondLevel) super.clone();

        // 修改SecondLevel这个对象中，引用类型的成员变量的值，让他指向，复制之后的成员变量所指向对象地址
        return clone;
    }
}

class ThirdLevel implements Cloneable {
    int thirdIntValue;
    double thirdDouleValue;

    public ThirdLevel(int thirdIntValue, double thirdDouleValue) {
        this.thirdIntValue = thirdIntValue;
        this.thirdDouleValue = thirdDouleValue;
    }
}

参考答案：

 

 

 

 

package com.day015;

//完成对FirstLevel对象的深度克隆。

/*
 * 实现深度克隆的思路：
 * 1.首先每个类，知道自己有哪些成员变量，成员变量中哪些是引用类型成员变量
 * 2.所以让每个类自己实现对自己的深度克隆方法
 * 3.实现深度克隆就变得简单了：
 *         a.首先利用super.clone(),即object的clone方法，完成对自己的克隆
 *         b.如果，本类中，有引用类型的成员，那么因为所有类都是实现了对自己的深度克隆
 *           所以，直接调用引用类型成员所指向对象的clone方法，让他们自己完成自己的深度克隆
 *         c.将引用类型成员变量的值，让他们指向深度克隆后的对象
 * 
 * 这个思想有些类似于递归思想
 * 
 */
public class Demo1 {

    public static void main(String[] args) throws CloneNotSupportedException {
        //测试object拷贝
        ThirdLevel thirdLevel = new ThirdLevel(30,30.3);
        SecondLevel secondLevel = new SecondLevel(20, 20.2, thirdLevel);
        FirstLevel firstLevel = new FirstLevel(10, 10.1, secondLevel);


        System.out.println("原对象：" + firstLevel);
        //利用clone方法进行复制
        FirstLevel firstClone = (FirstLevel) firstLevel.clone();
        System.out.println("克隆对象：" + firstClone);
        
        //修改原始对象
        secondLevel.secondIntValue = 22222;
        thirdLevel.thirdIntValue = 333;

        System.out.println("修改后的原对象：" + firstLevel);
        System.out.println("修改后的复制对象：" + firstClone);

    }

}

class FirstLevel implements Cloneable {
    int firstIntValue;
    double firstDoubleValue;
    SecondLevel second;

    public FirstLevel(int firstIntValue, double firstDoubleValue, SecondLevel second) {
        this.firstIntValue = firstIntValue;
        this.firstDoubleValue = firstDoubleValue;
        this.second = second;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        // 利用Object的Clone方法//复制FirstLevel对象本身
        FirstLevel clone = (FirstLevel) super.clone();

        // 修改 first对象中引用类型成员变量，比如 second 成员变量引用，指向被复制的那个FirstLevel对象的second对象的拷贝，
        clone.second = (SecondLevel) second.clone();
        return clone;
    }

    @Override
    public String toString() {
        return "FirstLevel [firstIntValue=" + firstIntValue + ", firstDoubleValue=" + firstDoubleValue + ", second="
                + second + "]";
    }
    
}

class SecondLevel implements Cloneable {
    int secondIntValue;
    double secondDoubleValue;
    ThirdLevel third;

    public SecondLevel(int secondIntValue, double secondDoubleValue, ThirdLevel third) {
        this.secondIntValue = secondIntValue;
        this.secondDoubleValue = secondDoubleValue;
        this.third = third;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        SecondLevel clone = (SecondLevel) super.clone();

        // 修改SecondLevel这个对象中，引用类型的成员变量的值，让他指向，复制之后的成员变量所指向对象地址
//        ThirdLevel thirdLevel = (ThirdLevel) third.clone();
//        clone.third = thirdLevel;
        clone.third = (ThirdLevel) third.clone();
        return clone;
    }

    @Override
    public String toString() {
        return "SecondLevel [secondIntValue=" + secondIntValue + ", secondDoubleValue=" + secondDoubleValue + ", third="
                + third + "]";
    }
    
}

class ThirdLevel implements Cloneable {
    int thirdIntValue;
    double thirdDouleValue;

    public ThirdLevel(int thirdIntValue, double thirdDouleValue) {
        this.thirdIntValue = thirdIntValue;
        this.thirdDouleValue = thirdDouleValue;
    }
    
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    @Override
    public String toString() {
        return "ThirdLevel [thirdIntValue=" + thirdIntValue + ", thirdDouleValue=" + thirdDouleValue + "]";
    }
    
}