CODEWITHSUNDEEP
javaswingoop
WreckTangle
WreckTangle

Reputation: 1

How do I access an objects methods through a different class?

So basically I have a main (DrawDriver) where I create 2 objects at the top.

 public class DrawDriver {

  public static void main(String[] args) {

    final GraphicPanel pannel1 = new GraphicPanel();        
   final Frame2UserInput pannel2 = new Frame2UserInput();

    TitledBorder border = new TitledBorder("Input");
    border.setTitleColor(Color.BLACK);      
   pannel2.setBorder(border);

    JFrame frame = new JFrame("DrawGoGo!");
   frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setPreferredSize(new Dimension(500, 500));
   frame.setLayout(new GridLayout(2, 0)); 
    frame.pack();       
   frame.setVisible(true);      
   frame.setResizable(false);

            // Creating the MENU BAR

            JMenuBar menubar = new JMenuBar(); 
           frame.setJMenuBar(menubar); 
            JMenu file = new JMenu("File"); 
        menubar.add(file); 
        JMenuItem New = new
           JMenuItem("New"); // Creates the jmenu item      
           file.add(New); // adds
           JMenuItem Load = new JMenuItem("Load");
            file.add(Load);         
           JMenuItem Save = new JMenuItem("Save");
            file.add(Save);         
           JMenuItem Exit = new JMenuItem("Exit");
            file.add(Exit);
            JMenu help = new JMenu("Help");     
            menubar.add(help);      

           JMenuItem about = new JMenuItem("About");        
           help.add(about);

            frame.getContentPane().add(pannel1);        
           frame.getContentPane().add(pannel2);



 }

In Frame2UserInput I want to access the GraphicPanel instance through the DrawDriver (main) class. This will be a canvas where I can type commands in & click the button & then the canvas will draw accordingly. You can see I've attempted to access it already in my ActionListener but can't because it makes a new instance of the class & not changes anything in the program (gui) I run.

So how would I access the object I created for GraphicPanel in the main but through a different class ? Any help would be appreciated thank you!

    public class Frame2UserInput extends JPanel {

    private static JTextArea input;     
       private static JButton draw;

        Frame2UserInput() {

                   input = new JTextArea(2,35);         
                  add(input);
                   draw = new JButton("Draw!");         
                  draw.addActionListener(new DrawListener());       
                  add(draw);    
   }        

   private static class DrawListener implements ActionListener {

            private String userInput;
            GraphicPanel pannel1 = new GraphicPanel();

            public void actionPerformed(ActionEvent event)  {


           if (event.getSource()==draw) {

            userInput = input.getText();
            System.out.println(userInput);

            if (userInput.equalsIgnoreCase("penup")) {

            }

            if (userInput.equalsIgnoreCase("pendown")) {

            }

            if (userInput.equalsIgnoreCase("turnleft")) {

            }

            if (userInput.equalsIgnoreCase("turnright")) {

            }
            if (userInput.equalsIgnoreCase("black")) {

            }

            if (userInput.equalsIgnoreCase("green")) {

            }

            if (userInput.equalsIgnoreCase("red")) {
                pannel1.drawLine(Color.RED,0,0,100,100);
            }

            if (userInput.equalsIgnoreCase("reset")) {
                pannel1.clear();
            }

                        }
                }   }    }

Upvotes: 0

Views: 72

Answers (4)

Adam Lyu
Adam Lyu

Reputation: 461

You can

  1. make it as a parameter of your class
  2. make it as a static class member(Not recommend). But it save your time in some degree if you operate on the same canvas.

Upvotes: 1

MadProgrammer
MadProgrammer

Reputation: 347294

Basically, you want to start by setting an Observer Pattern, where DrawDriver listens to events from Frame2UserInput and makes changes to the instance of GraphicPanel.

This is also a conceptual example of the Model-View-Controller paragdigm.

The idea here is, neither GraphicPanel or Frame2UserInput have any idea of each other (and shouldn't really know about DrawDriver either). DrawDriver is the bridge between the two, passing information between them as needed.

This will decouple your code and make it easier to modify and expand in the future, as changing one part shouldn't change how the other parts work. To this end, you should make heavy use of interfaces to define the core contractual logic between these classes.

Also, don't rely on static, it's not helping you and you should learn to work without it

Upvotes: 2

rdonuk
rdonuk

Reputation: 3956

Take it as a parameter.

final GraphicPanel pannel1 = new GraphicPanel();        
final Frame2UserInput pannel2 = new Frame2UserInput(pannel1 );

New Frame2UserInput constructor:

Frame2UserInput(GraphicPanel pannel1) {
   .
   .
   draw.addActionListener(new DrawListener(pannel1));    
}

And new DrawListener constructor

DrawListener(GraphicPanel pannel1) {
    .
    .
    //Don't need this just use pannel1 
    //GraphicPanel pannel1 = new GraphicPanel();
}

Upvotes: 2

mewc
mewc

Reputation: 1447

The dot operator 

object.objectMethod();

the method must be public, or protected if there is a level of inheritance & polymorphism going on

For your case, few pointers:

  • firstly your spelling of panel is wrong.
  • MEANINGFUL NAMES for your variable names is so very important

panel1 or panel2 are awful names for variables.

Next, you'd need to have an object in DrawDriver class to call an objects method from

Upvotes: 1

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