How to call Java package

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I have two classes which is in different packages (folder). How can I call variable from FirstClass.java to see the variable in the SecondClass.java. If all variables is public.

first class is in -> C:\workspace\First\FirstClass.java

second class is in -> C:\workspace\Second\SecondClass.java

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I think that you mean that the 2 classes are in different eclipse (I assume you are using eclipse) projects.
In you Project->Properties->BuildPath add a reference from one project to the other
Then you will be able to use the classes

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Beware that packages are not folders. Packages are sort of "virtual" folders, corresponding to a certain path. These packages may be located at very different places on your file system, and even in different sorts of files (like Java ARchive files, named *.jar for example).

In your question, it is not clear what is the classpath of your project. I'll assume that the root of your project is C:/workspace.

So, FirstClass is in the package First. Second class is in the package Second.

(By the way, you should stick to the conventions of java, which say that a package has always lowercase characters.)

In that case, in order to access you'll have to put:

package First;
import Second.SecondClass; // <- Here is the import.
class First{
  // ...
}

at the beginning of your FirstClass.java file. SecondClass has to be defined as a public class to do so.

package Second;

public class SecondClass{
  // ...
}

If you forget the 'public' keyword, your class is only visible for classes in the same package.

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If the variables reside as public fields in the classes, there should be no problem accessing the fields from outside code, despite the different packages.

...
package first;
public class First {
  public Integer var;
  ...
}

...
package second;
public class Second {
  public Integer var;

  public void test(Second other) {
    System.out.println(other.var);
  }
...

}

If you have problems, maybe you have them in different projects, as your paths suggest? Java-code only spans the same project on Eclipse.

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For demonstration purposes, this code should work:

Files in first/First.java and second/Second.java

package first;

public class First {
    public int x;
}


//////////////////////////////////////

package second;

import first.First;

public class Second {
    private int y = new First().x;
}