JAVA数组的扩容（逻辑上增加数组的长度）

package com.yh.test;

public class Test_1 {

public static void main(String[] args) {

int[] a = {1,2,3};
a = (int[])resizeArray(a,10);
a[3] = 4;
a[4] = 5;
a[5] = 6;
for (int i=0; i<a.length; i++)
System.out.println (a[i]);

}

private static Object resizeArray(Object oldArray, int newSize) {
int oldSize = java.lang.reflect.Array.getLength(oldArray);
Class elementType = oldArray.getClass().getComponentType();

Object newArray = java.lang.reflect.Array.newInstance(elementType,
newSize);
int preserveLength = Math.min(oldSize, newSize);
if (preserveLength > 0)
System.arraycopy(oldArray, 0, newArray, 0, preserveLength);
return newArray;
}
}