How do I fix a NoSuchMethodError?

Question

I\'m getting a NoSuchMethodError error when running my Java program. What\'s wrong and how do I fix it?

Answer 1

One such instance where this error occurs: I happened to make a silly mistake of accessing private static member variables in a non static method. Changing the method to static solved the problem.

Answer 2

I was having your problem, and this is how I fixed it. The following steps are a working way to add a library. I had done the first two steps right, but I hadn't done the last one by dragging the ".jar" file direct from the file system into the "lib" folder on my eclipse project. Additionally, I had to remove the previous version of the library from both the build path and the "lib" folder.

Step 1 - Add .jar to build path

Step 2 - Associate sources and javadocs (optional)

Step 3 - Actually drag .jar file into "lib" folder (not optional)

Answer 3

I have just solved this error by restarting my Eclipse and run the applcation. The reason for my case may because I replace my source files without closing my project or Eclipse. Which caused different version of classes I was using.

Answer 4

I've encountered this error too.

My problem was that I've changed a method's signature, something like

void invest(Currency money){...}

into

void invest(Euro money){...}

This method was invoked from a context similar to

public static void main(String args[]) {
    Bank myBank = new Bank();

    Euro capital = new Euro();
    myBank.invest(capital);
}

The compiler was silent with regard to warnings/ errors, as capital is both Currency as well as Euro.

The problem appeared due to the fact that I only compiled the class in which the method was defined - Bank, but not the class from which the method is being called from, which contains the main() method.

This issue is not something you might encounter too often, as most frequently the project is rebuilt mannually or a Build action is triggered automatically, instead of just compiling the one modified class.

My usecase was that I generated a .jar file which was to be used as a hotfix, that did not contain the App.class as this was not modified. It made sense to me not to include it as I kept the initial argument's base class trough inheritance.

The thing is, when you compile a class, the resulting bytecode is kind of static, in other words, it's a hard-reference.

The original disassembled bytecode (generated with the javap tool) looks like this:

 #7 = Methodref          #2.#22         // Bank.invest:(LCurrency;)V

After the ClassLoader loads the new compiled Bank.class, it will not find such a method, it appears as if it was removed and not changed, thus the named error.

Hope this helps.

Answer 5

If your file name is different than the class name which contain main method then it may be the possibility that this error may cause.