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;
	}
}

轻微解释：

a = (int[])resizeArray(a,10);

中数组长度逻辑上阔充到10；length为10.