The document discusses different Swing layouts in Java including: - BorderLayout (default JFrame layout with north, south, east, west, center areas) - BoxLayout (stacks components vertically or horizontally and sizes to components) - FlowLayout (arranges components in left-to-right flow that does not change if resized) - GridLayout (arranges components in a grid with equal number of rows and columns) - GridBagLayout (most flexible with grid-like placement and stretching of components using constraints) The most flexible is GridBagLayout but it is also more complex to implement than others like BorderLayout. GridBagLayout allows components to stretch to available space the most out

1. Lecture 10
Swing layouts
Object Oriented Programming
Eastern University, Dhaka
Md. Raihan Kibria

2. Specifying no layout in JFrame
public class DefaultLayoutDemo {
public static void main(String[] args) {
JFrame frame = new JFrame("DefaultLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set up the content pane.
frame.add(new JButton("a"));
frame.add(new JButton("b"));
//Display the window.
frame.pack();
frame.setVisible(true);
}
}

3. Specifying positions of controls
public class DefaultLayoutDemo {
public static void main(String[] args) {
JFrame frame = new JFrame("DefaultLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Set up the content pane.
frame.add(new JButton("a"), BorderLayout.NORTH);
frame.add(new JButton("b"), BorderLayout.SOUTH);
//Display the window.
frame.pack();
frame.setVisible(true);
}
}
The default layout for JFrame is
BorderLayout

4. BorderLayout
public class BorderLayoutDemo {
public static boolean RIGHT_TO_LEFT = false;
public static void addComponentsToPane(Container pane) {
if (RIGHT_TO_LEFT) {
pane.setComponentOrientation(
java.awt.ComponentOrientation.RIGHT_TO_LEFT);
}
JButton button = new JButton("Button 1 (PAGE_START)");
pane.add(button, BorderLayout.PAGE_START);
button = new JButton("Button 2 (CENTER)");
button.setPreferredSize(new Dimension(200, 100));
pane.add(button, BorderLayout.CENTER);
button = new JButton("Button 3 (LINE_START)");
pane.add(button, BorderLayout.LINE_START);
button = new JButton("Long-Named Button 4 (PAGE_END)");
pane.add(button, BorderLayout.PAGE_END);
button = new JButton("5 (LINE_END)");
pane.add(button, BorderLayout.LINE_END);
}

5. public static void main(String[] args) {
JFrame frame = new JFrame("BorderLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addComponentsToPane(frame.getContentPane());
frame.pack();
frame.setVisible(true);
}
}
If you stretch the frame the center part gets filled by the control in it

6. BoxLayout
public class BoxLayoutDemo {
public static void addComponentsToPane(Container pane) {
pane.setLayout(new BoxLayout(pane, BoxLayout.Y_AXIS));
addAButton("Button 1", pane);
addAButton("Button 2", pane);
addAButton("Button 3", pane);
addAButton("Long-Named Button 4", pane);
addAButton("5", pane);
}
private static void addAButton(String text, Container container) {
JButton button = new JButton(text);
button.setAlignmentX(Component.CENTER_ALIGNMENT);
container.add(button);
}
public static void main(String[] args) {
JFrame frame = new JFrame("BoxLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addComponentsToPane(frame.getContentPane());
frame.pack();
frame.setVisible(true);
}
}

7. Result
There is no resizing when the frame is stretched out

8. FlowLayout
public class FlowLayoutDemo extends JFrame{
FlowLayout experimentLayout = new FlowLayout();
public FlowLayoutDemo(String name) {
super(name);
}
public void addComponentsToPane(final Container pane) {
JPanel compsToExperiment = new JPanel();
compsToExperiment.setLayout(experimentLayout);
experimentLayout.setAlignment(FlowLayout.LEADING);
//Add buttons to the experiment layout
compsToExperiment.add(new JButton("Button 1"));
compsToExperiment.add(new JButton("Button 2"));
compsToExperiment.add(new JButton("Button 3"));
compsToExperiment.add(new JButton("Long-Named Button 4"));
compsToExperiment.add(new JButton("5"));
//Left to right component orientation is selected by default
compsToExperiment.setComponentOrientation(
ComponentOrientation.LEFT_TO_RIGHT);
pane.add(compsToExperiment, BorderLayout.CENTER);
}

9. public static void main(String[] args) {
FlowLayoutDemo frame = new FlowLayoutDemo("FlowLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.addComponentsToPane(frame.getContentPane());
frame.pack();
frame.setVisible(true);
}
}
If we stretch the controls are still pinned to the left because
of this:
experimentLayout.setAlignment(FlowLayout.LEADING);

10. GridLayout
public class GridLayoutDemo {
public static void addComponentsToPane(Container pane) {
pane.setLayout(new GridLayout(3, 2));
JButton b1 = new JButton("First");
pane.add(b1);
b1 = new JButton("Second");
pane.add(b1);
b1 = new JButton("Third");
pane.add(b1);
b1 = new JButton("Fourth");
pane.add(b1);
b1 = new JButton("Fifth");
pane.add(b1);
b1 = new JButton("Sixth");
pane.add(b1);
}
public static void main(String[] args) {
JFrame frame = new JFrame("GridBagLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addComponentsToPane(frame.getContentPane());
frame.pack();
frame.setVisible(true);
}

11. Result
3 columns and 2 rows as set in:
pane.setLayout(new GridLayout(3, 2));

12. GridBagLayout
public class GridBagLayoutDemo {
public static void addComponentsToPane(Container pane) {
JButton button;
pane.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
button = new JButton("Button 1");
c.gridx = 0;
c.gridy = 0;
pane.add(button, c);
button = new JButton("Button 2");
c.gridx = 1;
c.gridy = 0;
pane.add(button, c);
button = new JButton("Button 3");
c.gridx = 2;
c.gridy = 0;
pane.add(button, c);
button = new JButton("Long-Named Button 4");
c.gridx = 0;
c.gridy = 1;
pane.add(button, c);

13. button = new JButton("5");
c.gridx = 1;
c.gridy = 2;
pane.add(button, c);
}
public static void main(String[] args) {
JFrame frame = new JFrame("GridBagLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addComponentsToPane(frame.getContentPane());
frame.pack();
frame.setVisible(true);
}
}
GridBagLayout is very flexible layout

14. Questions
 What is the most flexible of these layouts
 Whichone is easy to implement
 Which layout to choose when you want
your control to take up as much space as
possible
 Interested in more? -
 GroupLayout
 SpringLayout