我想知道有没有办法做以下事情.我有一个抽象类,Shape和其所有不同的子类,我想覆盖克隆方法.所有我想要做的方法是从当前的toString()创建一个新的Shape.显然,我不能做以下,因为Shape是抽象的.有另一种方法来做,因为每个子类中的覆盖克隆只是为了简单的名称更改似乎是无用的.
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()
}
}
解决方法
你可以尝试使用反射：
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()方法中调用getClass().因为ACloneble是抽象的,所以会打电话到具体的类.
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
但它比解决方案更是一个黑客
[编辑]我的两个克隆比…快)
[编辑]要完成clone()的另一个含义可以是
@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;
}
当你的抽象类实现Serialazable.在那里,您将您的对象写入光盘,并创建具有光盘值的副本.
