69 lines
1.8 KiB
Java
69 lines
1.8 KiB
Java
// references/AddingClone.java
|
|
// (c)2016 MindView LLC: see Copyright.txt
|
|
// We make no guarantees that this code is fit for any purpose.
|
|
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
|
|
// You must go through a few gyrations
|
|
// to add cloning to your own class.
|
|
import java.util.*;
|
|
|
|
class Int2 implements Cloneable {
|
|
private int i;
|
|
public Int2(int ii) { i = ii; }
|
|
public void increment() { i++; }
|
|
@Override
|
|
public String toString() {
|
|
return Integer.toString(i);
|
|
}
|
|
@Override
|
|
public Object clone() {
|
|
Object o = null;
|
|
try {
|
|
o = super.clone();
|
|
} catch(CloneNotSupportedException e) {
|
|
System.err.println("Int2 can't clone");
|
|
}
|
|
return o;
|
|
}
|
|
}
|
|
|
|
// Inheritance doesn't remove cloneability:
|
|
class Int3 extends Int2 {
|
|
private int j; // Automatically duplicated
|
|
public Int3(int i) { super(i); }
|
|
}
|
|
|
|
public class AddingClone {
|
|
@SuppressWarnings("unchecked")
|
|
public static void main(String[] args) {
|
|
Int2 x = new Int2(10);
|
|
Int2 x2 = (Int2)x.clone();
|
|
x2.increment();
|
|
System.out.println(
|
|
"x = " + x + ", x2 = " + x2);
|
|
// Anything inherited is also cloneable:
|
|
Int3 x3 = new Int3(7);
|
|
x3 = (Int3)x3.clone();
|
|
ArrayList<Int2> v = new ArrayList<>();
|
|
for(int i = 0; i < 10; i++ )
|
|
v.add(new Int2(i));
|
|
System.out.println("v: " + v);
|
|
ArrayList<Int2> v2 =
|
|
(ArrayList<Int2>)v.clone();
|
|
// Now clone each element:
|
|
for(int i = 0; i < v.size(); i++)
|
|
v2.set(i, (Int2)v2.get(i).clone());
|
|
// Increment all v2's elements:
|
|
for(Int2 i2 : v2)
|
|
i2.increment();
|
|
System.out.println("v2: " + v2);
|
|
// See if it changed v's elements:
|
|
System.out.println("v: " + v);
|
|
}
|
|
}
|
|
/* Output:
|
|
x = 10, x2 = 11
|
|
v: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
|
|
v2: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
|
|
v: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
|
|
*/
|