动态的扩展现有数组

import java.lang.reflect.Array;




public class ArrayGrowTest {
public static void main(String args[]) {
int[] a = {1, 2, 3};
a = (int[]) goodArrayGrow(a);

String[] b = {"Tom", "Dick", "Harry"};
b = (String[]) goodArrayGrow(b);

System.out.println("The following call will generate an exception");

b = (String[]) badArrayGrow(b);
}

static Object goodArrayGrow(Object a) {
Class cl = a.getClass();
if(!cl.isArray()) return null;
Class componentType = cl.getComponentType();
int length = Array.getLength(a);
int newLength = length * 11/10+10;

Object newArray = Array.newInstance(componentType, newLength);

System.arraycopy(a, 0, newArray, 0, length);
return newArray;
}

/** 整形数组可以转换成Object，但无法转换成Object[]                       */
static Object[] badArrayGrow(Object[] a) {
int newLength = a.length * 11 / 10 + 10;
Object[] newArray = new Object[newLength];
System.arraycopy(a, 0, newArray, 0, a.length);
return newArray;
}
}