Question

So I just started with Java a few weeks ago and I am trying to teach myself how to make my own methods. I made a program that adds two numbers when I compile the class “ClassTest”. Here is the error:

H:\Java Things\ClassTest.java:10: error: cannot find symbol
            GetNum(int1, int2);
        ^
  symbol:   method GetNum(int,int)
  location: class ClassTest
1 error

Process completed.

Here is the code for ClassTest:

import LotsOfMethods.*;

public class ClassTest
{
    public static void main (String[] args)
    {
        int int1 = 5, int2 = 7;
        GetNum(int1, int2);
    }
}

And here is the code for ExampleMethod:

package LotsOfMethods;

public class ExampleMethod
{
    public static int GetNum(int num1, int num2)
    {
        int result;
        result = num1 + num2;
        return result;
    }
}

Answer 1

First, it’s important to recognize how you call a method in Java. You need to specify the object who will fulfill the method, and the name of the method that you’re calling.

When you write:

GetNum(int1, int2);

You’re not specifying an object that will execute GetNum. Java has some default behavior to handle this case: it tries to resolve the method from the object context surrounding your code. So Java says, “I can’t find a GetNum() method belonging to this ClassTest object,” and you get the error:

H:\Java Things\ClassTest.java:10: error: cannot find symbol
            GetNum(int1, int2);

The method that you want is in the class ExampleMethod. It is a static method attached to the ExampleMethod class, which means you don’t need to instantiate a copy in order to get there. Instead, you can do:

int result = ExampleMethod.GetNum(int1, int2);

Classes with static methods provide a sort of namespace around those methods, and so the class itself provides enough data to resolve your method. If you had a non-static method, you’d need to do something like:

ExampleMethod example = new ExampleMethod();
int result = example.GetNum(int1, int 2);

I hope this helps.