如何将JScrollPane添加到JPanel

Question

I have been searching around for an easy way to implement a JScrollPlane . I am trying to add it to a JPanel , and it will contain a dynamic number of JPanel s (which will be filled with other stuff).

Here is my (failing miserably) attempt to make said JScrollPane :

final JPanel info = new JPanel();
final JScrollPane infoS = new JScrollPane(info,ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
info.setLayout(new GridLayout(0,1));
info.setLocation(10,78);
info.setSize(420,490);
infoS.setPreferredSize(new Dimension(600, 600));
gui.add(infoS);

Answer 1

In this example , a series of nested panels are added to a panel having BoxLayout . That panel is used to create a JScrollPane which is then added to a JFrame .

public class BoxTest extends JPanel {
...
JScrollPane jsp = new JScrollPane(this,
    JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
    JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
...
JFrame f = new JFrame();
f.add(jsp); // BorderLayout.CENTER, by default

Answer 2

The primary problem you're having is the fact that the default layout manager's layout is set to FlowLayout , which means that the JScrollPane will want to use it's preferred size to be layout with, which may not fill the entire panel.

Instead, use a BorderLayout

final JPanel info = new JPanel(new BorderLayout()); // <-- Change me :D
final JScrollPane infoS = new JScrollPane(info,ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
// These are bad ideas, setLocation and setSize won't work, as the panel should be
// under the control of a layout manager
//info.setLocation(10,78);
//info.setSize(420,490);
//infoS.setPreferredSize(new Dimension(600, 600));
gui.add(infoS);