类定义

package Reflect;public class MyTest {    public int a;    public static int b;    public static final int c = 0;    private int d;    public int sum(int a, int b) {        return a + b;    }    public int sub(int a, int b, String c) {
     　　　　System.out.println(c);         return a - b;    }    MyTest() {    }    MyTest(int a, int b) {    }}

反射调用

package Reflect;import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.lang.reflect.Modifier;public class Test {    public static void main(String[] args) {                // invoke the reflect-method        try {            final Class z = Class.forName("Reflect.MyTest");            final Class[] params = new Class[3];// define the param-type            params[0] = int.class;            params[1] = int.class;            params[2] = String.class;            // final Method m = z.getDeclaredMethod("sub", params);            final Method m = z.getMethod("sub", int.class, int.class, String.class);            // final Method m = z.getDeclaredMethod("sum", int.class, int.class);            // set in-param            final Object[] p = new Object[3];            p[0] = 100;            p[1] = 50;            p[2] = "hello word!";            System.out.println();            final Integer s = (Integer) m.invoke(z.newInstance(), p);            // final Integer s = (Integer) m.invoke(z.newInstance(), 3, 5);            System.out.println("return value==" + s);        } catch (final Exception e) {            e.printStackTrace();        }    }}

输出：

hello word!

return value==50