在将Java反射与Double []作为参数一起使用时，获取noSuchMethodException

Question

I have the following method signature:

public synchronized List<Bet> acceptTheBets(Double[] odds, BrokerState bs)

I am trying to use reflection to invoke this method, however I get the following exception:

java.lang.NoSuchMethodException: regions.BettingCenter.acceptTheBets([D, entities.BrokerState)

Why does it result in NoSuchMethodException ?

Answer 1

Here is a quick example on how to use this

public class A {
    public static void main(String[] args) {
        try {
            Object a = new double[]{1.0, 2.0};
            System.out.println(A.class.getMethod("getStrings", double[].class).invoke(new A(), a));
        } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | NoSuchMethodException | SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public synchronized List<String> getStrings(double[] array){
        return DoubleStream.of(array).boxed().map(d -> "" + d).collect(Collectors.toList());
    }

}

Notice the Object used to prevent that a is seen as 2 parameter for the varargs. Also, you need to pass an instance to invoke the method in it.

This works also for Double[] but need to pass the specific type Double[].class to get the correct method.

public String getStrings(double[] array){
    return "double[]";
}

public String getStrings(Double[] array){
    return "Double[]";
}

Will be called with :

//double[]
A.class.getMethod("getStrings", double[].class)
    .invoke(new A(), (Object)new double[]{1.0, 2.0}));

//Double[]
A.class.getMethod("getStrings", Double[].class)
    .invoke(new A(), (Object)new Double[]{1.0, 2.0}));

Notice the differences of types and arguments passed.

Answer 2

[D is double[] not Double[] . check https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.3.2 . It looks you are passing argument with wrong type.