java数组克隆

看到网上很多讲述java数组克隆的文章，其中给出的例子都不是很完整，有很多不给解释说明，所以经常会让初学者误解。今天闲来无事就写了这么一个程序，请各位参考。

我给出的解释不是很多，但只强调两点：

1. 数组的结构：基本类型数组，仅是一个数组对象；对象类型的数组，是一个数组对象引用一系列对象。

2. 数组对象有 clone 方法，该方法是浅克隆。即：通过该方法返回的对象仅克隆数组对象，如果是对象类型的数组，并不克隆它引用的对象。

虽然下面的程序没有注释，但基于以上两点认识，就可以完整的理解程序。

package org.joy.usmile;

public class Main {

public static 
void printArray(String head, int[] array) {
System.out.print(head + " *==>");
for (int a : array) {
System.out.print(a);
System.out.print("\t");
}
System.out.println();
}

public static <T> 
void printArray(String head, T[] array) {
System.out.print(head + " ==>");
for (T a : array) {
System.out.print(a);
System.out.print("\t");
}
System.out.println();
}

public static 
void main(String[] args) {
test1();
test2();
test3();
}

private static 
void test1() {
int[] a = { 1, 
2, 3, 4, 
5 };
int[] b = new 
int[a.length];

printArray("a : ", a);
printArray("b : ", b);
System.out.println();

b = a.clone();

printArray("a : ", a);
printArray("b : ", b);
System.out.println();

b[0] = 100;

printArray("a : ", a);
printArray("b : ", b);
System.out.println();
}

private static 
void test2() {
Integer[] ao = { 1, 2,
3, 4, 
5 };
Integer[] bo = new Integer[ao.length];

printArray("ao : ", ao);
printArray("bo : ", bo);
System.out.println();

bo = ao.clone();

printArray("ao : ", ao);
printArray("bo : ", bo);
System.out.println();

bo[0] = 200;

printArray("ao : ", ao);
printArray("bo : ", bo);
System.out.println();
}

private static 
void test3() {
class Ox {
public String name;

public Ox(String name) {
this.name = name;
}

@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("[");
sb.append(this.name);
sb.append("]");
return sb.toString();
}
}

Ox[] oa = { new Ox("a"),
new Ox("b"), 
new Ox("c"), new Ox("c"),
new Ox("d") };
Ox[] ob = new Ox[oa.length];

printArray("Ox a", oa);
printArray("Ox b", ob);
System.out.println();

ob = oa.clone();

printArray("Ox a", oa);
printArray("Ox b", ob);
System.out.println();

ob[0] = new Ox("Love");

printArray("Ox a", oa);
printArray("Ox b", ob);
System.out.println();

ob[ob.length - 1].name = "[* U Joy *]";

printArray("Ox a", oa);
printArray("Ox b", ob);
System.out.println();
}
}

package org.joy.usmile;

public class Main {

	public static void printArray(String head, int[] array) {
		System.out.print(head + " *==>");
		for (int a : array) {
			System.out.print(a);
			System.out.print("\t");
		}
		System.out.println();
	}

	public static <T> void printArray(String head, T[] array) {
		System.out.print(head + " ==>");
		for (T a : array) {
			System.out.print(a);
			System.out.print("\t");
		}
		System.out.println();
	}

	public static void main(String[] args) {
		test1();
		test2();
		test3();
	}

	private static void test1() {
		int[] a = { 1, 2, 3, 4, 5 };
		int[] b = new int[a.length];

		printArray("a : ", a);
		printArray("b : ", b);
		System.out.println();

		b = a.clone();

		printArray("a : ", a);
		printArray("b : ", b);
		System.out.println();

		b[0] = 100;

		printArray("a : ", a);
		printArray("b : ", b);
		System.out.println();
	}

	private static void test2() {
		Integer[] ao = { 1, 2, 3, 4, 5 };
		Integer[] bo = new Integer[ao.length];

		printArray("ao : ", ao);
		printArray("bo : ", bo);
		System.out.println();

		bo = ao.clone();

		printArray("ao : ", ao);
		printArray("bo : ", bo);
		System.out.println();

		bo[0] = 200;

		printArray("ao : ", ao);
		printArray("bo : ", bo);
		System.out.println();
	}

	private static void test3() {
		class Ox {
			public String name;

			public Ox(String name) {
				this.name = name;
			}

			@Override
			public String toString() {
				StringBuilder sb = new StringBuilder();
				sb.append("[");
				sb.append(this.name);
				sb.append("]");
				return sb.toString();
			}
		}

		Ox[] oa = { new Ox("a"), new Ox("b"), new Ox("c"), new Ox("c"),
				new Ox("d") };
		Ox[] ob = new Ox[oa.length];

		printArray("Ox a", oa);
		printArray("Ox b", ob);
		System.out.println();

		ob = oa.clone();

		printArray("Ox a", oa);
		printArray("Ox b", ob);
		System.out.println();

		ob[0] = new Ox("Love");

		printArray("Ox a", oa);
		printArray("Ox b", ob);
		System.out.println();

		ob[ob.length - 1].name = "[* U Joy *]";

		printArray("Ox a", oa);
		printArray("Ox b", ob);
		System.out.println();
	}
}