Hello,
I had a hard time trying to get the following done, but I'm totally stuck. The initial situation is this:
I have a JFrame with a JScrollPane in it. The content (more precisely the viewPortView) of that scroll pane is my own class "MyComponent", which extends a JPanel. What this MyComponent class does is to dynamically creates some JLabels and adding it to itself. I can parameterize it (in my example code below) to specify how many JLabels should be created. The layout of MyComponent is "TableLayout", and for each added JLabel I first create a new row (so every JLabel is in it's own row). I could say that MyComponent is a bit like a JTable.
The problem is: I need to set the preferred size (only the height) of MyComponent, so the surrounding JScrollPane can display it's scroll bars correctly. That is all - and I just don't know where and when I must set the size.
Some thoughts about the problem:
- I can set the height of MyComponent not until the frame (or
dialog...) has been displayed (setVisible(true)).
- I think it is correct that the Layout Manager (TableLayout) must
first layout all JLabels in MyComponent, and than I must use the
"layout.preferredLayoutSize( container )" method to determine the
real size (height)? I'm not sure about this..
- Maybe I must override amethod of MyComponent in which I calculate
and/or set the height of MyComponent?
- I'm not sure, but the JTable component does the same thing? It is
a component, that "grows vertically" and lies in a JScrollPane,
therefore must adjust it's own size to the JScrollPane is able to
display the scroll bars correctly.
To make things easier to understand, I wrote a small program to demonstrate my problem. It consists of two simple classes - the first one creates the window and the scrollpane, the second class is the MyComponent:
public class CustomCompInScrollpaneTest {
public CustomCompInScrollpaneTest() {
// Creating the frame
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(800, 600);
frame.setLocationRelativeTo(null);
frame.setLayout(null);
// Create Scrollpane
JScrollPane scrollPane = new JScrollPane();
scrollPane.setSize(300, 300);
scrollPane.setPreferredSize(new Dimension(300, 300));
scrollPane.setLocation(100, 100);
// Add MyComponent with 5 rows to the scrollpane
scrollPane.setViewportView(new MyComponent(5));
// Add scrollpane to frame and show it
frame.add(scrollPane);
SwingUtilities.invokeLater(new Runnable() {
@Override public void run() {
frame.setVisible(true);
}
});
}
public static void main(String[] args) {
new CustomCompInScrollpaneTest();
}
}
The second class is the interesting one:
public class MyComponent extends JPanel {
public MyComponent(int count) {
// Create table layout with just one column and 0 rows (rows get added in the for loop)
TableLayout layout = new TableLayout(new double[] {TableLayout.FILL}, new double[0]);
setLayout(layout);
// Set preferred size - by setting this, especially the x-value, the
// line/word wrapping of the JLabels will work
setPreferredSize(new Dimension(0, 0));
// Create count rows
for (int row = 0; row < count; row++) {
JLabel label = new JLabel();
label.setBorder( BorderFactory.createLineBorder(Color.RED));
label.setText(
"<html>" +
"<div style='font-size:18px'>" +
"This is JLabel #" + ( row + 1 ) + ".<br>" +
"And this is the second line of the label text." +
"</div>" +
"</html>"
);
// Insert a new row and adding the JLabel
layout.insertRow(row, TableLayout.PREFERRED);
add(label, "0, " + row);
}
}
}
(The only dependency of the example above is the TableLayout layout manager.)
The second class is the one, that should set it's own size - if I understand that correctly.
Please have a look at the line "setPreferredSize(new Dimension(0, 0));", when I omit the line, the JLabel-word-wrap does not work. I need to set the x value of the preferred size at least to get word wrapping.
The question is now, where and how must I set the preferred height of MyComponent? Or is it the complete wrong way or do I misunderstand anything here? Isn't the JTable doing the same?
I really appreciatie any help you can give me
Thanks a lot!
Best Regards,
Ben