Java基础 深拷贝浅拷贝

Java基础 深拷贝浅拷贝

• 非基本数据类型 需要new新空间

class Student implements Cloneable{
    private int id;
    private String name;
    private Vector course;

    public Student(){
        try{
            Thread.sleep(1000);
            System.out.println("Student Constructor called.");
        }catch (InterruptedException e){
            e.printStackTrace();
        }
    }

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

    public int getId() {return id;}
    public void setId(int id) {this.id = id;}

    public Vector getCourse() {return course;}
    public void setCourse(Vector course) {this.course = course;}

    //浅拷贝
    public Student newInstance(){
        try{
            return (Student)this.clone();
        }catch (CloneNotSupportedException e){
            e.printStackTrace();
        }
        return null;
    }

    //深拷贝
    public Student deepClone(){
        try{
            Student cloning = (Student) super.clone();
            cloning.course = new Vector();
            return cloning;

        }catch (CloneNotSupportedException e){
            e.printStackTrace();
        }
        return null;
    }

}


public Object clone(){      //覆写clone()，深拷贝  
    try{  
        Student cloning = (Student) super.clone(); 
        // 这里不能使用Student cloning = (Student) this.clone()的原因:
        正在覆写本类的clone()方法，如果再调用本类的函数，即：this.clone()，就相当于无限递归无限死循环了，最终会崩溃的。所以这里：super.clone()。

        cloning.courses = new Vector();     //关键点：非基本数据类型的空间需要自己新开辟一块儿  
        return cloning;  
    }catch(CloneNotSupportedException e){  
        e.printStackTrace();  
    }  
    return null;  
}  

参考资料

谨慎覆盖clone
Java中的clone() 深拷贝 浅拷贝