How to make a JFrame scrollable in Java?

Question

I have this code in which I am trying to fit a scrollable Panel (JPanel) but I don't get it. Here is my code:

public class Sniffer_GUI extends JFrame {
Canvas c = new Canvas();
ConnectorPropertiesPanel props;
public Sniffer_GUI() {
    super("JConnector demo");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    getContentPane().setLayout(new GridBagLayout());
    init();

    getContentPane().add(new JLabel("Connectors example. You can drag the connected component to see how the line will be changed"),
                         new GridBagConstraints(0, 0, 2, 1, 1, 0, GridBagConstraints.NORTHWEST, GridBagConstraints.HORIZONTAL, new Insets(5, 5, 0, 5), 0, 0));
    getContentPane().add(initConnectors(),
                         new GridBagConstraints(0, 1, 1, 1, 1, 1, GridBagConstraints.NORTHWEST, GridBagConstraints.BOTH, new Insets(5, 5, 5, 5), 0, 0));
    getContentPane().add(props,
                         new GridBagConstraints(1, 1, 1, 1, 0, 1, GridBagConstraints.NORTHWEST, GridBagConstraints.VERTICAL, new Insets(5, 0, 5, 5), 0, 0));
    setSize(800, 600);
    setLocationRelativeTo(null);

}

Thanks in advance.

I edit to add a code that partially seems to work...

public Sniffer_GUI() {
    super("JConnector demo");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel container = new JPanel();
    JScrollPane scrPane = new JScrollPane(container);
    add(scrPane);
    scrPane.setLayout(new ScrollPaneLayout());
    init();

    add(initConnectors());

    setSize(800, 600);
    setLocationRelativeTo(null);

}

But it isn't still scrollable, at least it makes its function inside a JScrollPane, is a good step.

Solution 1

Make a JPanel scrollable and use it as a container, something like this:

JPanel container = new JPanel();
JScrollPane scrPane = new JScrollPane(container);
add(scrPane); // similar to getContentPane().add(scrPane);
// Now, you can add whatever you want to the container

Solution 2

To extend @Eng.Fouad answer:

public class Sniffer_GUI extends JFrame {
    Canvas c = new Canvas();
    ConnectorPropertiesPanel props;
    public Sniffer_GUI() {
        super("JConnector demo");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel container = new JPanel();
        JScrollPane scrPane = new JScrollPane(container);
        getContentPane().add(scrPane);
        container.setLayout(new GridBagLayout());
        init();

        container.add(new JLabel("Connectors example. You can drag the connected component to see how the line will be changed"),
                             new GridBagConstraints(0, 0, 2, 1, 1, 0, GridBagConstraints.NORTHWEST, GridBagConstraints.HORIZONTAL, new Insets(5, 5, 0, 5), 0, 0));
        container.add(initConnectors(),
                             new GridBagConstraints(0, 1, 1, 1, 1, 1, GridBagConstraints.NORTHWEST, GridBagConstraints.BOTH, new Insets(5, 5, 5, 5), 0, 0));
        container .add(props,
                             new GridBagConstraints(1, 1, 1, 1, 0, 1, GridBagConstraints.NORTHWEST, GridBagConstraints.VERTICAL, new Insets(5, 0, 5, 5), 0, 0));
        setSize(800, 600);
        setLocationRelativeTo(null);

    }
}

Solution 3

Maybe this will help...

JFrame frame = new JFrame();
JPanel panel = new JPanel();

// add something to you panel...
// panel.add(...);

// add the panel to a JScrollPane
JScrollPane jScrollPane = new JScrollPane(panel);
// only a configuration to the jScrollPane...
jScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
jScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

// Then, add the jScrollPane to your frame
frame.getContentPane().add(jScrollPane);

Solution 4

To make a component of a JFrame scrollable, wrap the component in a JScrollPane:

    JScrollPane myJScrollPane = new JScrollPane(myJLabel,
         JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
         JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);

and replace mentions of myJLabel with myJScrollPane. Worked for me.

Solution 5

Just chiming in, and feel free to correct me if I'm off base, but using a JScrollPane like that has an unintended consequence of requiring more frequent window resizing.

For example, I had a program where I set up a JFrame-wide scrollpane like that. I also had a JTextArea in a tab in the frame that was the same size as the content pane. This textArea was also in its own scrollpane (this was more of a screwing around project than anything else). When I loaded content from a file to deposit in the textArea, it triggered the scrollbars around the text area.

The result was that my, let's call it the innerScrollPane, was now larger than the JFrame because of the scrollbars, which hadn't been visible before. This then triggered what I'm now going to call the outerScrollPane, to display its scrollbars, which then covered up the inner scrollbars.

This was easily resolved by adding an extra window.pack() argument to the end of my file opening method, but I just wanted to throw this out there. The scrollbars can potentially cover up content in the window if you're not careful. But... well there are a million ways to prevent this problem, so it's not a huge deal. Just something to be aware of.

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Comments

[Guillaume Polet]

Adding elements to the scrollpane is usually not what you want. Usually, you pass the container panel to the constructor of JScrollPane or you use setViewportView

[Joe Lewis]

I get problems with the layout of scrPane when I try to add elements, how could I do something similiar to the original code?

[Guillaume Polet]

@JoeLewis Instead of doing what you do with the content pane, do it on the container described in Eng.Fouad's answer and simply add the scrollpane to the content pane (leave the default layout, BorderLayout, as the layout manager of the content pane)

[Joe Lewis]

@Guillaume Polet ok perfect Eng.Fouad's code is partially working as I edited in the original post, it works but it isn't still scrollable...

[Guillaume Polet]

@JoeLewis I posted and answer based on your code and Eng.Fouad proposal.

[Joe Lewis]

My hero... xD Now I just need to make it vertically scrollable, since it's just horizontal... :P

[Guillaume Polet]

@JoeLewis You can set the vertical and horizontal scroll bar policies to adjust this things. Consider reading the ScrollPane tutorial and also its JavaDoc

[Joe Lewis]

My problem is, that iniConnectors() retrieves a JPanel and I need to make scrollable that Panel, since it's the most important, however I can't do it even adding initConnector to another JScrollPane and then do container.add("the new JScrollPane", etc...);

[Guillaume Polet]

@JoeLewis I doubt that you need nested ScrollPane here, but I can't know for sure without seeing all your code. If you only want scrolling to apply to your JPanel initConnector, then keep your original code but use the following: getContentPane().add(new JScrollPane(initConnectors()),... instead of getContentPane().add(initConnectors(),...

[Filipe Brito]

Thank you to show the JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED and JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED inside JScrollPane's constructor. In my answer I'm using setVerticalScrollBarPolicy and setHorizontalScrollBarPolicy method instead. Thank you for this possibility.