68 lines
1.8 KiB
Java
68 lines
1.8 KiB
Java
// references/AddingClone.java
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// (c)2020 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://OnJava8.com for more book information.
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// You must go through a few gyrations
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// to add cloning to your own class
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import java.util.*;
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import java.util.stream.*;
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class Int2 implements Cloneable {
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private int i;
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Int2(int ii) { i = ii; }
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public void increment() { i++; }
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@Override
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public String toString() {
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return Integer.toString(i);
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}
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@Override
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public Int2 clone() {
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try {
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return (Int2)super.clone();
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} catch(CloneNotSupportedException e) {
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throw new RuntimeException(e);
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}
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}
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}
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// Inheritance doesn't remove cloneability:
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class Int3 extends Int2 {
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private int j; // Automatically duplicated
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Int3(int i) { super(i); }
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}
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public class AddingClone {
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@SuppressWarnings("unchecked")
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public static void main(String[] args) {
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Int2 x = new Int2(10);
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Int2 x2 = x.clone();
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x2.increment();
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System.out.println(
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"x = " + x + ", x2 = " + x2);
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// Anything inherited is also cloneable:
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Int3 x3 = new Int3(7);
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x3 = (Int3)x3.clone();
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ArrayList<Int2> v = IntStream.range(0, 10)
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.mapToObj(Int2::new)
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.collect(Collectors
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.toCollection(ArrayList::new));
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System.out.println("v: " + v);
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ArrayList<Int2> v2 =
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(ArrayList<Int2>)v.clone();
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// Now clone each element:
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IntStream.range(0, v.size())
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.forEach(i -> v2.set(i, v.get(i).clone()));
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// Increment all v2's elements:
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v2.forEach(Int2::increment);
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System.out.println("v2: " + v2);
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// See if it changed v's elements:
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System.out.println("v: " + v);
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}
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}
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/* Output:
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x = 10, x2 = 11
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v: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
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v2: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
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v: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
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*/
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