如何获得调用方法的返回值

Question

我试图在java中实现某种反射。我:

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

为您的参考放置虚拟类，您可以相应地更改代码-

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;
    }
}

Answer 2

invoke()方法返回该方法执行后返回的对象!所以你可以试试…

Double dd = (Double)method.invoke(this,x);
double retunedVal = dd.doubleValue();