CODEWITHSUNDEEP
java
Bart Wesselink
Bart Wesselink

Reputation: 286

NoSuchMethodFound exception

I keep getting this error message:

06-13 18:53:33.839: W/System.err(19893): java.lang.NoSuchMethodException: showIt
06-13 18:53:33.839: W/System.err(19893):    at java.lang.ClassCache.findMethodByName(ClassCache.java:247)
06-13 18:53:33.839: W/System.err(19893):    at java.lang.Class.getDeclaredMethod(Class.java:731)

I'm sure my method exists, I try to start from within a asynctask. This is the method:

public static void showIt(String[] result) {

And this is the code I've tried:

try {
            Class<?> p = Class.forName(executeClass);
            Object t = p.newInstance();

            Method m = p.getDeclaredMethod(executeMethod, p);
            m.invoke(t, result);
        } catch (Exception e) {
            e.printStackTrace();
        }

Upvotes: 1

Views: 347

Answers (3)

Andrea Parodi
Andrea Parodi

Reputation: 5614

You got two mistakes here:

  1. you have to pass getDeclaredMethod the type of argument as second parameter, and not the type of your class (p)
  2. since your method is static, you have to pass null as first parameter to invoke, and you don't need to create the t instance.

.

public class Main {
    public static void main(String[] args){


        try {
            Class<?> p = Main.class;

            String[] arguments = {"ciao"};
            Method m = p.getDeclaredMethod("showIt",String[].class);

            m.invoke(null, arguments);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void showIt(String[] result) {
        System.out.println(result[0]);
    }
}

Upvotes: 0

Toilal
Toilal

Reputation: 3399

Three problems ...

  • getDeclaredMethod second argument must be an array of parameters classes of the showIt method.

  • Because the method is static, it is useless to pass an object to the first argument of invoke method.

  • Because the invoke method is varargs, result must be wrapped into a Object[] in order to be passed as excepted.

Finally, here is a working code snipet.

String[] result = new String[] { "res" };
Class<?> p = Class.forName(executeClass);

Method m = p.getDeclaredMethod("showIt", result.getClass());
m.invoke(null, new Object[] {result});

Upvotes: 1

Sebastian Redl
Sebastian Redl

Reputation: 71909

Given executeClass = "YourClass" and executeMethod = "showIt", p.getDeclaredMethod(executeMethod, p) is trying to find showIt(YourClass arg), but you have showIt(String[] arg).

Try p.getDeclaredMethod(executeMethod, String[].class).

Upvotes: 1

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