how can i arrange the component to the left side in Boxlayout?

[Zamioculcas]

Hi Everybody,

I am confused with BoxLayout...
I have 2 components on my frame. (a button , and a table) And I used BoxLayout to arrange these components.

When I run my application, I noticed, my button was misaligned. It seems it was randomly placed.
I would like to put that button to the left side of the panel.

How can I achive this? Might I omit anything from my settings ?
May I use nested panels?

Thanks in advance for your help.

here is my simplified code

import javax.swing.*;
import javax.swing.table.*;
import java.awt.event.*;
import java.awt.*;
public class TableData extends JFrame implements ActionListener{


String[] header = {"name", "gift", "piece"};
DefaultTableModel model = new DefaultTableModel(header, 3);
JTable table = new JTable(model);
JPanel panel = new JPanel();
JButton buttonOK = new JButton("OK");

public TableData()
{
	panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
	panel.add(buttonOK);
	buttonOK.addActionListener(this);
	buttonOK.setAlignmentX(Component.LEFT_ALIGNMENT);

	
	panel.add(new JScrollPane(table));
	getContentPane().add(panel);
	
	setSize(400,200);
	setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	setTitle("Christmas gifts");
	setVisible(true);
	
	
}
public void actionPerformed(ActionEvent e)
{
	if (e.getActionCommand().equals("OK"))
		{
			System.out.println("ok");

		}
}

public static void main(String[] args)
	{
		new TableData();
	}

}

[pbrockway2]

I would like to put that button to the left side of the panel.

The following left aligns the button with the table:

panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
Box box = Box.createHorizontalBox();
/* suggested in http://docs.oracle.com/javase/tutorial/uiswing/layout/box.html#alignment
buttonOK.setBorder(BorderFactory.createCompoundBorder(
        BorderFactory.createLineBorder(Color.red),
        buttonOK.getBorder()));
*/
box.add(buttonOK);
box.add(Box.createHorizontalGlue());
panel.add(box);
buttonOK.addActionListener(this);
//buttonOK.setAlignmentX(Component.LEFT_ALIGNMENT);

Basically you nest box containers and add glue and struts to taste. I've found this a good recipe.

This sort of question ought to be posed in the Swing forum to better catch the eye of one of the Swing experts who can explain why setAlignmentX() failed to. (In the past I've been caught out by not appreciating the impact of the different sizes of a component: actual, min, max and preferred.)

[camickr]

See: How to Use BoxLayout (The Java™ Tutorials > Creating a GUI With JFC/Swing > Laying Out Components Within a Container) to better understand how alignment works.

[pbrockway2]

As shown in the code I posted, that's where I went! But when am I going to learn how to read...? I managed to convince myself it was a size problem.

@OP: there is a picture there -

The numbers are the alignments: LEFT on top of CENTRE on top of RIGHT. The image is called wacky.png. Indeed. But the text at the start of the page explains how it gets to be that way. And in the bit camickr linked to they offer the advice "In general, all the components controlled by a top-to-bottom BoxLayout object should have the same X alignment".

panel.setLayout(new BoxLayout(panel,BoxLayout.Y_AXIS));
panel.add(buttonOK);
buttonOK.addActionListener(this);
buttonOK.setAlignmentX(Component.LEFT_ALIGNMENT);

JScrollPane scroll = new JScrollPane(table);
scroll.setAlignmentX(Component.LEFT_ALIGNMENT); // <-----
panel.add(scroll);

getContentPane().add(panel);

That whole page is worth reading. Twice.

[Zamioculcas]

Very thanks your reply, it solved my problem. I tried out and tested the your mentioned Box class and its methods, and it really makes better the visualization.
Furthermore I tested the createRigidArea(Dimension d) method to let space between components.

Thanks again.

[pbrockway2]

You're welcome.