CODEWITHSUNDEEP
javareflection
user2490373
user2490373

Reputation: 153

Java/ Taking method without specify its parameters

Is there any way to take a method using reflection without specifying its parameters?

I tried this:

method = className.class.getMethod("nameOfTheMethod");

Where nameOfTheMethod is a function with 5 parameters.

But it thinks that nameOfTheMethod is a function without parameters, and gives me java.lang.NoSuchMethodException.

Upvotes: 1

Views: 181

Answers (4)

LuigiEdlCarno
LuigiEdlCarno

Reputation: 2415

You need to specify the Parameter types

Try

Class[] cArg = new Class[5];
cArg[0] = Long.class;
cArg[1] = Long.class;
cArg[2] = Long.class;
cArg[3] = Long.class;
cArg[4] = Long.class;
Method lMethod = c.getMethod("nameOfMethod", cArg);

Replace the longs with whatever type your parameters are of respectively.

Upvotes: 0

Bengt
Bengt

Reputation: 4038

You can achieve this by using getDeclaredMethods() and iterating the returned array.

    Method[] methods = className.class.getDeclaredMethods();
    for (Method m : methods) {
        if (m.getName().equals("nameOfTheMethod")) {
            // found
            break;
        }
    }

This way has the downside, that it only works reliable for not overloaded methods. However, you can easily take this further, so an array or set of all methods with the specified name is found.

Upvotes: 1

Jonathan Drapeau
Jonathan Drapeau

Reputation: 2610

You can't do it like that, the getMethod needs the number of parameters.

What you could use is getMethods or getDeclaredMethods, depending what you're looking for, and match any of them with the name you want.

You could get more than 1 of them matching the name but with different parameters.

getMethods will

Returns an array containing Method objects reflecting all the public member methods of the class or interface represented by this Class object, including those declared by the class or interface and those inherited from superclasses and superinterfaces

while getDeclaredMethods will

Returns an array of Method objects reflecting all the methods declared by the class or interface represented by this Class object. This includes public, protected, default (package) access, and private methods, but excludes inherited methods.

Upvotes: 1

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 279960

You can get all methods

declared by the class or interface represented by this Class object.

with

Method[] methods = ClassName.class.getDeclaredMethods();

Iterate through them and find yours. This isn't safe if your method is overloaded as you will still have to check the parameters.

Upvotes: 2

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