Did I properly encapsulate this package?

My goal is to make File_Path_Handler constructor the only thing a user can access. Oh, is it too coupled? but the main question is: is File_Path_Handler the only accessible part of this package?

The handler:

package file_path_handler;

//| File_Path_Handler
//| - a component that lets the user pick a file, 
//|      then the file path will be displayed accordingly

//| imports
    import javax.swing.JPanel;  //? the base class

    import java.awt.BorderLayout;  //? the organizing layout

public class File_Path_Handler extends JPanel {
    private File_Path_Load_Button button;
    private File_Path_Display display;  //? the UI part

    private File_Path_Load_Button_Click_Listener trigger;
    private File_Path_Relay relay;  //? the internal logic part

    //| constructor
    public File_Path_Handler( final String button_label, final String default_display_label ) {
        this.display = new File_Path_Display( default_display_label );  //? the UI part

        this.relay = new File_Path_Relay( display );
        this.trigger = new File_Path_Load_Button_Click_Listener( relay );  //? the logic that wires all the UI together

        this.button = new File_Path_Load_Button( button_label, trigger );  //? the other UI part

        this.setLayout( new BorderLayout() );
        this.add( button, BorderLayout.WEST );
        this.add( display, BorderLayout.CENTER );
    }
}

The display:

package file_path_handler;

// imports
    import javax.swing.JTextField;  //? the base class

//|    File_Path_Display
//|    - displays the current selected file
class File_Path_Display extends JTextField {  //? the public interface will be the JPanel that houses this couplet, this can stay hidden in the package
    public File_Path_Display( final String default_label ) {
        this.setText( default_label );
        this.setEnabled( false );
    }

    public void update_text( final String file_path ) {
        this.setText( file_path );
    }
}

The ActionLi

package file_path_handler;

Package names should be in the format tld.organization.application.package. For example like this:

package com.company.application.package;
package com.github.username.application;
package com.gmail.username.application;

This can be ignored for test applications and similar, but the moment you release code "into the wild" you should make sure that it is in a correct package.

//| File_Path_Handler
//| - a component that lets the user pick a file, 
//|      then the file path will be displayed accordingly

What is this? You should always use JavaDoc to document your code. Not some obscure self-made format that is incompatible with everything.

If in doubt, look at the documentation of the language you're using. Never forget, you're not the first to use that language, you're not the first who needs whatever you need, somebody else already did it and they did it better in 99% of the cases.

//| imports
import javax.swing.JPanel;  //? the base class

import java.awt.BorderLayout;  //? the organizing layout

Again, these comments are not helpful in any way and should be left out.

public class File_Path_Handler extends JPanel {

This violates the Java Naming Conventions which state the classes should be UpperCamelCase.

private File_Path_Load_Button button;

This violates the Java Naming Conventions which state that the variables should be lowerCamelCase.

Also prefixing every variable with the class name is not helpful and not a good idea. It only clutters up everything and having a "common prefix" for variables is the whole idea of classes in the first place.

public File_Path_Handler( final String button_label, final String default_display_label ) {

This violates the Java Naming Conventions which states the functions should be lowerCamelCase with the exception of constructors which mimic the class name. Also variable names.

StackExchange Code Review Q#45777, answer score: 5