主函数：

import java.lang.reflect.Field;public class reflec {    public static void main(String[] args) throws NoSuchMethodException, ClassNotFoundException, IllegalAccessException {        TestClassEx t = new TestClassEx();            for (Field f : t.getClass().getDeclaredFields()) {                if(f.getName().equals("leijun")) {                    f.setAccessible(true);                    f.set(t, "indian MI fans");                    System.out.println(f.getName()+":"+f.get(t));                }            }    }}

实体类：

class TestClassEx extends TestClass{    public String leijun = "are you ok?";}

运行结果：

leijun:indian MI fans

Process finished with exit code 0