JAVA功能代码《13》----在Java中调整数组大小

13.在Java中调整数组大小

public class resizeArray {
	/**
	 * Reallocates an array with a new size, and copies the contents of the old
	 * array to the new array.
	 * 
	 * @param oldArray
	 *            the old array, to be reallocated.
	 * @param newSize
	 *            the new array size.
	 * @return A new array with the same contents.
	 */
	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;
	}

	// Test routine for resizeArray().
	public static void main(String[] args) {
		int[] a = { 1, 2, 3 };
		a = (int[]) resizeArray(a, 5);
		a[3] = 4;
		a[4] = 5;
		for (int i = 0; i < a.length; i++)
			System.out.println(a[i]);
	}
}