Java克隆抽象对象

Question

我想知道是否有办法做到以下几点.我有一个抽象类,Shape以及它的所有不同的子类,我想重写克隆方法.我想在方法中做的就是Shape从toString()当前的一个创建一个新的.显然我不能做以下因为Shape是抽象的.还有另一种方法可以做到这一点,因为在每个子类中重写克隆只是为了简单的名称更改似乎没用.

public abstract class Shape {

    public Shape(String str) {
        // Create object from string representation
    }

    public Shape clone() {
        // Need new way to do this
        return new Shape(this.toString());   
    }

    public String toString() {
        // Correctly overriden toString()
    }
}

Answer 1

您可以尝试使用反射:

public abstract class AClonable implements Cloneable{

private String val;

public AClonable(){

}

public AClonable(String s){
    val=s;
}

public String toString(){
    return val;
}

@Override
public AClonable clone(){
    try {
        System.out.println(getClass().getCanonicalName());
        AClonable b= getClass().getDeclaredConstructor(String.class).newInstance(val);

        return b;
    } catch (InstantiationException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchMethodException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return null;
}

}

在clone()方法中,您调用getClass().因为ACloneble是抽象的,所以调用将总是进入具体类.

   public class ClonebaleOne extends AClonable{

public ClonebaleOne(){
    super();
}

public ClonebaleOne(String s) {
    super(s);
    // TODO Auto-generated constructor stub
}

}

和

  public class ClonebaleTwo extends AClonable{

public ClonebaleTwo(){
    super();
}

public ClonebaleTwo(String s) {
    super(s);
    // TODO Auto-generated constructor stub
}

}

最后

   public static void main(String[] args){
    AClonable one = new ClonebaleOne("One");
    AClonable tow= new ClonebaleTwo("Two");
    AClonable clone = one.clone();
    System.out.println(clone.toString());
    clone = tow.clone();
    System.out.println(clone.toString());

}

输出:

  ClonebaleOne
  One
  ClonebaleTwo
  Two

但它更像是一个黑客而不是一个解决方案

[编辑]我的两个克隆比...更快

[编辑]完成.clone()的另一个实现可以是

 @Override
public AClonable clone(){
    try {
        ByteArrayOutputStream outByte = new ByteArrayOutputStream();
        ObjectOutputStream outObj = new ObjectOutputStream(outByte);
        ByteArrayInputStream inByte;
        ObjectInputStream inObject;
        outObj.writeObject(this);
        outObj.close();
        byte[] buffer = outByte.toByteArray();
        inByte = new ByteArrayInputStream(buffer);
        inObject = new ObjectInputStream(inByte);
        @SuppressWarnings("unchecked")
        Object deepcopy =  inObject.readObject();
        inObject.close();
        return (AClonable) deepcopy;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

当您的抽象类实现Serialazable时.在那里,您将对象写入光盘并使用光盘中的值创建副本.