java reflect反射调用方法invoke

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