1 /**
2 * @author zhengbinMac
3 */
4 public class Test {
5 public static void main(String[] args) {
6 int[] array1 = {1,2,3,4,5};
7 // 1.通过for循环
8 int[] array2 = new int[5];
9 for(int i = 0;i < array1.length;i++) {
10 array2[i] = array1[i];
11 }
12 for(int i = 0;i < array2.length;i++) {
13 System.out.print(array2[i]);
14 }
15 System.out.println();
16 //2.通过System.arraycopy()
17 int[] array3 = new int[5];
18 System.arraycopy(array1, 0, array3, 0, 5);
19 for (int i = 0; i < array3.length; i++) {
20 System.out.print(array3[i]);
21 }
22 System.out.println();
23 //3.通过Arrays.copyOf()
24 int[] array4 = new int[5];
25 array4 = Arrays.copyOf(array1, 5);
26 for (int i = 0; i < array4.length; i++) {
27 System.out.print(array4[i]);
28 }
29 System.out.println();
30 //4.通过Object.clone()
31 int[] array5 = new int[5];
32 array5 = array4.clone();
33 for (int i = 0; i < array5.length; i++) {
34 System.out.print(array5[i]);
35 }
36 }
37 }
1.for循环方法:
代码灵活,但效率低。
2.System.arraycopy()方法:
通过源码可以看到,其为native方法,即原生态方法。自然效率更高。
1 public static native void arraycopy(Object src, int srcPos,
2 Object dest, int destPos,
3 int length);
3.Arrays.copyOf()方法:
同样看源码,它的实现还是基于System.arraycopy(),所以效率自然低于System.arraycpoy()。
1 public static int[] copyOf(int[] original, int newLength) {
2 int[] copy = new int[newLength];
3 System.arraycopy(original, 0, copy, 0,
4 Math.min(original.length, newLength));
5 return copy;
6 }
4.Object.clone()方法:
从源码来看同样也是native方法,但返回为Object类型,所以赋值时将发生强转,所以效率不如之前两种。
1 protected native Object clone() throws CloneNotSupportedException;