Layout Managers and preferred size

[Jennifer Sohl]

Hi. I am having a problem laying out a gui. I want to place five buttons and five labels on a panel. I want the button to have a corresponding label. I can do this with Grid Layout. However, I want the buttons to be small. Grid Layout will not let me set the size of the buttons. What would be the best way of going about this?
I'm pretty new with layout managers so bear with me (I was using visual age before to do GUI!).
Thanks a million!

[Dirk Schreckmann]

Hello,
One thing you might want to consider is explicitly placing components where you want them of the height and width you want them.

setLayout(null);

and then look at the Component.setBounds() method to set the location, height, and width.

Good Luck,
-Dirk Schreckmann
[ February 19, 2002: Message edited by: Dirk Schreckmann ]

[Manfred Leonhardt]

Hi Jennifer,
The beauty of java is that you can do it many different ways. See the code below to see how to do it using two different layout approaches.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class LayoutExample extends JFrame
{
  private String[] buttonNames = { "One", "Two", "Three", "Four", "Five" };
  private String[] labelValues = { "First button", "Second button", 
                                   "Third button", "Fourth button", 
                                   "Fifth button" };
  public LayoutExample()
  {
    super( "Grid Bag Example" );
    //
    // First panel uses GridBag.
    //
    JPanel panel = new JPanel( new GridBagLayout() );
    panel.setBorder( new TitledBorder( "GridBag" ) );
    GridBagConstraints gc = new GridBagConstraints();
    gc.gridwidth = 1;
    gc.gridheight = 1;
    gc.insets = new Insets( 5, 5, 5, 5 );
    //
    // Loop through and add each component.
    // 
    for( int i = 0; i < buttonNames.length; ++i )
    {
      gc.gridx = 0;
      gc.gridy = i;
      gc.anchor = GridBagConstraints.CENTER;
      //
      // Force buttons to be all same size.
      //
      gc.fill = GridBagConstraints.HORIZONTAL;
      panel.add( new JButton( buttonNames[i] ), gc );
      gc.gridx = 1;
      gc.fill = GridBagConstraints.NONE;
      gc.anchor = GridBagConstraints.WEST;
      panel.add( new JLabel( labelValues[i] ), gc );
    }
    //
    // Set layout correctly for GridBag usage.
    //
    Container cont = getContentPane();
    cont.setLayout( new BorderLayout() );
    cont.add( panel, "West" );
    //
    // Second layout uses two grids inside one borderlayout.
    //
    JPanel otherPanel = new JPanel( new BorderLayout() );
    otherPanel.setBorder( new TitledBorder( "Complex" ) );
    JPanel btnPanel = new JPanel( new GridLayout( 5, 0, 5, 5 ) );
    JPanel lblPanel = new JPanel( new GridLayout( 5, 0, 5, 5 ) );
    for( int i = 0; i < buttonNames.length; ++i )
    {
      btnPanel.add( new JButton( buttonNames[i] ) );
      lblPanel.add( new JLabel( labelValues[i] ) );
    }
    JPanel p = new JPanel( new BorderLayout( 5, 5 ) );
    p.add( btnPanel, "West" );
    p.add( lblPanel, "East" );
    otherPanel.add( p, "North" );
    cont.add( otherPanel, "East" );
    pack();
  }
  public static void main(String[] args) 
  {
    new LayoutExample().setVisible( true );
  }
}

Enjoy,
Manfred.

[Paul Stevens]

Why do people always want to cop out and suggest and use null layout?

[Dirk Schreckmann]

Hello,
Did you feel like making an intelligent argument to not know about setLayout(null)?
[ February 19, 2002: Message edited by: Dirk Schreckmann ]

[Rob Ross]

Null layouts totally loose out on the dynamic resize features of layout managers.
I have never worked on UI code that at some point did not need some kind of modification. If you hard code every position and size on your screen, you have a TON of extra work to add a button here or a combo box there.
Don't use null layouts. Learn to harness the power of LayoutManager!!!

[Paul Stevens]

I have yet to see a UI that has to use the null layout. Once you use it, you also have to set the resizing of your window to off. If you don't, you have to place a great deal of code into your app just to make it appear proportional to where you started. The Layout Managers provide all of this functionality for you. The argument has been made many times in this forum against the use of null layout. It is a broken record. The difference between the null layout and the others is that it takes time to learn the other layouts and how they can be combined to do whatever you want. We can also talk about adding new components to an existing layout. Using the null all components need to be repositioned manually. With the other layout managers you may just need to add the component. If you need more argements against the use of null layout, just search this forum. There are plenty against.
Now why don't you provide an argument for their use.

[Jane Griscti]

Hi Jennifer,
You can also get what you want by creating a custom component. Try the following, it produces 5 10x10 labeled buttons.

package examples.swing;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
/**
 *  A panel with a small labeled button.
 *
 *@author     [e-mail]
 *@created    February 20, 2002
 */
public class LabeledButton extends JPanel {
    private final  JLabel   label   = new JLabel();
    private final  JButton  button  = new JButton();

    /**  Constructs a new LabeledButton object */
    public LabeledButton() {
        this( "" );
    }

    /**
     *  Constructs a new LabeledButton object
     *
     *@param  labelText  Description of Parameter
     */
    public LabeledButton( final String labelText ) {
        button.setPreferredSize( new Dimension( 10, 10 ) );
        button.setBackground( Color.blue );
        label.setText( labelText );
        add( label );
        add( button );
    }

    /**
     *  Sets the buttonSize attribute of the LabeledButton object
     *
     *@param  width   The new buttonSize value
     *@param  height  The new buttonSize value
     */
    public void setButtonSize( final int width, final int height ) {
        button.setSize( new Dimension( width, height ) );
    }

    /**
     *  Sets the labelText attribute of the LabeledButton object
     *
     *@param  text  The new labelText value
     */
    public void setLabelText( final String text ) {
        label.setText( text );
    }

    /**
     *  Gets the button attribute of the LabeledButton object
     *
     *@return    The button value
     */
    public JButton getButton() {
        return button;
    }

    /**
     *  Gets the label attribute of the LabeledButton object
     *
     *@return    The label value
     */
    public JLabel getLabel() {
        return label;
    }

    /**
     *  The main program for the LabeledButton class
     *
     *@param  args  The command line arguments
     */
    public static void main( String[] args ) {
        JFrame     frame   = new JFrame( "Test LabeledButton" );
        frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        Container  cp      = frame.getContentPane();
        cp.setLayout( new GridLayout( 1, 1 ) );
        String[]   labels  = {"One", "Two", "Three", "Four", "Five"};
        for( int i = 0; i < 5; i++ ) {
            cp.add( new LabeledButton( labels[i] ) );
        }
        frame.pack();
        frame.setVisible( true );
    }
}

Hope that helps.
[ February 20, 2002: Message edited by: Jane Griscti ]