import - Java error - bad source file: file does not contain class x . Please remove or make sure it appears

Question

Recently started studying Java for an exam.

While learning packages, tried this and got an error message. What I did was,

---

    //Creating class A (Within package the package: com.test.helpers)

    package com.test.helpers;
    public class A {
        public void sayHello(){
            System.out.println("Hello World");
        }
    }

---

    //And then the class App utilizing the class A

    import com.test.helpers.*;

    public class App{
        public static void main(String args[]){
            A a = new A();
            a.sayHello();
        }
    }

---

I had both of these files in a directory called 'JavaTest' (on Windows 7), and first compiled the A.java using the command javac -d . A.java

And then, while attempting to compile App.java, I got the following error message:

---

    App.java:5: error: cannot access A
                    A a = new A();
                    ^
      bad source file: .A.java
        file does not contain class A
        Please remove or make sure it appears in the correct subdirectory of the source path.
    1 error

---

However, the problem seems to resolve in two ways,

1. Deleting the Source file A.java
2. Changing the import statement from import com.test.helpers.*; to import com.test.helpers.A in the file, 'App.java'.

I'd be highly grateful if you can explain what happens here. Or I might be making a goofy human mistake or a syntax error.

Here's the link to the source files

Thank you very much

Answer 1

Hi the problem here is that the JVM confuses the class file due to the ambiguous class file name in both the directory (the JavaTest as well as the com.test.helpers directory).

when you do javac -d . A.java the compiler makes a class file in the directory com.test.helpers and now it confuses it with the sourcefile there in JavaTest

1. Deleting the Source file A.java

When you delete the source file A.java from JavaTest, JVM knows now that the class file in com.test.... is to be used, ambiguity goes away.

2. Changing the import statement from 'import com.test.helpers.*;' to 'import com.test.helpers.A' in the file, 'App.java'.

Here you are specifying which particular file to use in your class implementation that is you are telling the compiler to use the file A.java from com.test... and not from JavaTest package

Now, the solution for this ambiguity to not ever be a problem for you, you must import the specific files with import statement i.e. import com.test.helpers.A; or if you want to do import com.test.helpers.*; then you must specifically use com.test.helpers.A in place of A everywhere in your current class implementation to tell the compiler not to confuse it with the source at JavaTest

I know it's a lot late for this particular answer, but I wanted to share my views for the upcoming readers, if it could help them in any way, it would be great. Thanks!