java - 如何获取调用方法的返回值？

Question

我正在尝试在 Java 中实现某种反射。我有:

class P {
  double t(double x) {
    return x*x;
  }

  double f(String name, double x) {
    Method method;
    Class<?> enclosingClass = getClass().getEnclosingClass();
     if (enclosingClass != null) {
        method = enclosingClass.getDeclaredMethod(name, x);
        try {
          method.invoke(this, x);
        } catch (Exception e) {
          e.printStackTrace();
        }

    }
}

class o extends P {
  double c() { 
    return f("t", 5);
  }
}

如何从 new o().c() 中获取值？

Answer 1

放置虚拟类供您引用，您可以相应地更改您的代码-

import java.lang.reflect.Method;

public class Dummy {

    public static void main(String[] args) throws Exception {
        System.out.println(new Dummy().f("t", 5));
    }

    double t(Double x) {
        return x * x;
    }

    double f(String name, double x) throws Exception {
        double d = -1;
        Method method;
        Class<?> enclosingClass = getClass();
        if (enclosingClass != null) {
            method = enclosingClass.getDeclaredMethod(name, Double.class);
            try {
                Object value = method.invoke(this, x);
                d = (Double) value;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        return d;
    }
}

只需运行这个类。