CODEWITHSUNDEEP
javaswing
user3685412
user3685412

Reputation: 4547

JScrollPane is changing it's size

I so my problem is this:

I made a JPanel. Inside it I want to add a JList with a scroll-bar. So I use JScrollPane.

Here you can see a picture of the application. The big white recangle is the size of the JPanel. In the second picture you see what happens when I add the Scrollpane to the code.

Size of the JPanel

Size of the JList with JScrollPane.

Here is the code I use:

public class GUI extends JFrame{

    DefaultListModel m = new DefaultListModel();
    JList myList = new JList(m);
    JScrollPane scrollPane = new JScrollPane(myList);
    JPanel listPanel = new JPanel();

    public GUI(){
    //Stuff about Frame Size, title, and other boring things

    scrollPane.setViewportView(myList);
    listPanel.add(scrollPane);
    this.add(listPanel);
    }
}

I have used it before, and it worked. Well, I faced the same problem, but it went away. I have written this code the same way as I did the previous time. But this time it doesn't work.

thanks in advance guys.

Upvotes: 0

Views: 337

Answers (3)

MadProgrammer
MadProgrammer

Reputation: 347194

With JList you can simply use setVisibleRowCount to adjust the size of the viewable area of the JScrollPane

The other problem is JPanel uses a FlowLayout by default, you may want to change the use something like BorderLayout instead

Updated

As pointed out, if the list contains a large number of elements, you can use setPrototypeValue to improve the efficiency

Upvotes: 1

TheJavaCoder16
TheJavaCoder16

Reputation: 591

By default, unless you use something like a grid bag layout...

Also, for developing UI's in Java, it is extremely helpful to install an eclipse plugin called WindowBuilder

Upvotes: 0

user3685412
user3685412

Reputation: 4547

Okay, so apparently I have to setPreferredSize. You can't just set the size of the panel, you need to set the size of the jscrolpane too!

Upvotes: 0

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