Adding JScrollPane to JPanel?

[Rus Corina]

I have a problem adding a JScrollPane to JPanel. I will write some code, maybe someone could please tell me what i'm doing wrong, because i've tried a lot of things and it still does not work.

public class Test extends JFrame {
   private JPanel pane = new JPanel();
   public Test() {
     super("Test");
     setBounds(0, 0, 1240, 900);
    pane.setLayout(null);
    final JScrollPane scrollp = new JScrollPane(pane);
    this.add(scrollp);
    setVisible(true);
   }
  public static void main(String[] arguments) {
        Test t = new Test();

     }
}

So mainly this is it, except that i have a lot of components that i add to the pane.

[Stephan van Hulst]

You should call your constructor on the Event Dispatch Thread:

public static void main(String... args) {
  SwingUtilities.invokeLater(new Runnable() {
    public void run() {
      Test t = new Test();
    }
  });
}

[Rus Corina]

Nope, that does not work either. Oh, i also forgot to mention, i set the dimension of the pane and of the scroll:

pane.setBounds(0, 0, 2000, 2000);
scrollp.setBounds(0, 0, 1240, 900);

right after declaring the scrollpane. Maybe this could be a problem?

[Rus Corina]

And also, I have a panel with fixed size, the client cannot change it's dimension (i mean, he can't add or remove components or anything to or from it), so all i need is a scrollpane that appears at the beginning. I managed to add a scrollpane to many components, like textAreas or tables, but i can't manage to add it to a panel

[Aditya Jha]

Why do you think that scroll-pane is not getting added? It's just that since there is nothing to scroll, the scroll-bars are not visible. The default policy for both vertical as well as horizontal scroll-bars is show-as-needed.

If you change the code a bit, then you can see the scroll-bars:

final JScrollPane scrollp = new JScrollPane(this.pane, 
        JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, 
        JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

[Rus Corina]

Then I think I have a different problem than i thought. I have the window above, which contains the main panel, called "pane". To this pane, i add around 14 other panels. But when i try to add the panels that normally don't fit inside the main panel viewport, the scroll does not work. And i have no idea why

[Rus Corina]

public class Verificari extends JFrame {

    //componentele ferestrei
    //etichete, camp text
    private JPanel pane = new JPanel();
    private JPanel pane1 = new JPanel();
    private JPanel pane2 = new JPanel();
    private JPanel pane3 = new JPanel();
    private JPanel pane4 = new JPanel();
    private JPanel pane5 = new JPanel();
    private JPanel pane6 = new JPanel();
    private JPanel pane7 = new JPanel();
    private JPanel pane8 = new JPanel();
    private JPanel pane9 = new JPanel();
    private JPanel pane10 = new JPanel();
    private JPanel pane11 = new JPanel();
    private JPanel pane12 = new JPanel();

    public Verificari() {

        super("Verificari");
        setBounds(0, 0, 500, 500);
        //setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        pane.setLayout(null);
        pane1.setLayout(null);
        pane2.setLayout(null);
        pane3.setLayout(null);
        pane4.setLayout(null);
        pane5.setLayout(null);
        pane6.setLayout(null);
        pane7.setLayout(null);
        pane8.setLayout(null);
        pane9.setLayout(null);
        pane10.setLayout(null);
        pane11.setLayout(null);
        pane12.setLayout(null);
        
        //here i define borders for all the panels
        Border eBorder1 = BorderFactory.createEtchedBorder();
        pane1.setBorder(BorderFactory.createTitledBorder(eBorder1, ""));
        
        Border eBorder2 = BorderFactory.createEtchedBorder();
        pane2.setBorder(BorderFactory.createTitledBorder(eBorder2, "Document"));

        Border eBorder3 = BorderFactory.createEtchedBorder();
        pane3.setBorder(BorderFactory.createTitledBorder(eBorder3, ""));

        Border eBorder4 = BorderFactory.createEtchedBorder();
        pane4.setBorder(BorderFactory.createTitledBorder(eBorder4, ""));

        Border eBorder5 = BorderFactory.createEtchedBorder();
        pane5.setBorder(BorderFactory.createTitledBorder(eBorder5, "VTP-RFR"));

        Border eBorder6 = BorderFactory.createEtchedBorder();
        pane6.setBorder(BorderFactory.createTitledBorder(eBorder6, "Identificare Client"));

        Border eBorder7 = BorderFactory.createEtchedBorder();
        pane7.setBorder(BorderFactory.createTitledBorder(eBorder7, "Date privind instalatia de ardere"));

        Border eBorder8 = BorderFactory.createEtchedBorder();
        pane8.setBorder(BorderFactory.createTitledBorder(eBorder8, "Verificarea documentelor"));

        Border eBorder9 = BorderFactory.createEtchedBorder();
        pane9.setBorder(BorderFactory.createTitledBorder(eBorder9, "Verificarea lucrarilor efectuate"));

        Border eBorder10 = BorderFactory.createEtchedBorder();
        pane10.setBorder(BorderFactory.createTitledBorder(eBorder10, "Verificari la rece"));

        Border eBorder11 = BorderFactory.createEtchedBorder();
        pane11.setBorder(BorderFactory.createTitledBorder(eBorder11, "Verificari la cald"));

        Border eBorder12 = BorderFactory.createEtchedBorder();
        pane12.setBorder(BorderFactory.createTitledBorder(eBorder12, "Verificarea parametrilor realizati"));

        
        final JScrollPane scrollp = new JScrollPane(pane, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);//this is for the main panel 
        
        
         
        
        pane.setBounds(0, 0, 2000, 2000);
        scrollp.setBounds(0, 0, 1240, 900);
        //here i set the bounds of all the components
        pane1.setBounds(10, 13, 200, 60);
        pane2.setBounds(220, 5, 200, 150);
        pane3.setBounds(440, 13, 200, 140);
        pane4.setBounds(660, 13, 130, 110);
        pane5.setBounds(810, 5, 130, 120);
        pane6.setBounds(10, 160, 300, 250);
        pane7.setBounds(330, 160, 230, 250);
        pane8.setBounds(580, 160, 360, 250);
        pane9.setBounds(10, 420, 270, 310);
        pane10.setBounds(290, 420, 330, 310);
        pane11.setBounds(630, 420, 520, 310);
               

        //here i add all the elements to the panel
        pane.add(pane1);
        pane.add(pane2);
        pane.add(pane3);
        pane.add(pane4);
        pane.add(pane5);
        pane.add(pane6);
        pane.add(pane7);
        pane.add(pane8);
        pane.add(pane9);
        pane.add(pane10);
        pane.add(pane11);
        pane.add(pane12);

        this.add(scrollp);
        setVisible(true);
    }

    public static void main(String[] arguments) {
        Verificari e = new Verificari();   
    
    }
}

this is my code. I have no idea what is wrong with it

[Rus Corina]

I got it to work. Just had to setPreferredSize for JPanel

[Aditya Jha]

Your panel's 'null' layout is the problem. Scroll-pane calculates its scroll-bars applicability using viewport's preferred size, and a panel with null layout returns (0, 0) as preferred size.

Change the code:

        final JScrollPane scrollp = new JScrollPane(pane, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

        pane.setBounds(0, 0, 2000, 2000);  

to:

		this.pane.setBounds(0, 0, 2000, 2000);
		this.pane.setPreferredSize(new Dimension(2000, 2000));

		final JScrollPane scrollp = new JScrollPane(this.pane, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

Regards,
- Aditya

[Rus Corina]

Thanks, it works

[Rob Camick]

So mainly this is it, except that i have a lot of components that i add to the pane.

Stop using "null layouts".

Swing was designed to be used with layout managers. One of the jobs of the the layout manager it to determine the "preferred size" of the panel once all the components are added to it.

You should NOT be setting the preferred size manually. Let the layout managers do their job.