创建一个Caculator 类

package org.example.caculator;

public class Caculator {
    private String name;
    public Caculator(){

    };
    public Caculator(String name){
        this.name = name;
    }
    public int add(int a,int b){
        return a+b;
    }
}

org.example.caculator.Caculator这个是 Caculator的路径，创建一个 o 对象，
通过 cls.getMethod 获取Caculator的add 方法 后面两个是add的两个参数，通过method.invoke();调用这个方法。

package org.example.caculator;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        Class<?> cls = Class.forName("org.example.caculator.Caculator");
        Object o = cls.newInstance();
        Method method = cls.getMethod("add", int.class, int.class);
        System.out.println(method.invoke(o,11,44));
    }
}