Most commonly will extend a JFrame or JWindow.

JWindow is a stripped-down window without title bar, maximize etc.

e.g., about box or splash screen

JFrame is a window with title bar, minimize, maximize and close buttons.

<4.1>

public class Lookup extends javax.swing.JFrame {

//...

}

<4.2>

import javax.swing.JFrame
public class SimpleFrame extends JFrame {
   public SimpleFrame() {
      super("Frame Title");
      setSize(300, 100);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setVisible(true);
   }

public static void main(String[] arguments) {
   SimpleFrame sf = new SimpleFrame();
   }
}

A simple window application, from book:

<4.3>

import javax.swing.JWindow;
public class SimpleWindow extends JWindow {
   public SimpleWindow() {
   super();
   setBounds(250, 225, 300, 150);
   }
public static void main(String[] arguments) {
   SimpleWindow sw = new SimpleWindow();
   sw.setVisible(true);
   for (int i = 0; i < 10000; i++)
   System.out.print(i + " ");
   sw.setVisible(false);
   System.exit(0);
   }
}

Components

A component is an object having a graphical representation that can be displayed on the screen and that can interact with the user. (java.awt.Component documentation)

Every component type has its own class. To create a component, you make an object of that class (instantiate) then place on a container.

Example: buttons

<4.4>

JButton play = new JButton("Play");
JButton rewind = new JButton("Rewind");

Containers

A component that can contain other AWT components. (java.awt.Container doc)

Example: JPanel

<4.5>

JButton quit = new JButton("Quit");
JPanel panel = new JPanel();
panel.add(quit);

Some Swing containers use panes which requires a different way of adding the components.

Includes JFrame, JWindow, JDialog and JApplet-- all the top-level containers.

You need to use a content pane, as in this book example:

<4.6>

import javax.swing.*;
public class Buttons extends JFrame {
   JButton abort = new JButton("Abort");
   JButton retry = new JButton("Retry");
   JButton fail = new JButton("Fail");

public Buttons() {
   super("Buttons");
   setSize(80, 140);
   setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   JPanel pane = new JPanel();
   pane.add(abort);
   pane.add(retry);
   pane.add(fail);
   setContentPane(pane);
}
public static void main(String[] arguments) {
   Buttons rb = new Buttons();
   rb.show();
   }
}

Here is another way to do it:

<4.7>

import javax.swing.*;
public class Buttons extends JFrame {
   JButton abort = new JButton("Abort");
   JButton retry = new JButton("Retry");
   JButton fail = new JButton("Fail");

   public Buttons() {
      super("Buttons");
      setSize(80, 140);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      //add to the already existing content pane
      getContentPane().add(abort);
      getContentPane().add(retry);
      getContentPane().add(fail);
   }
   public static void main(String[] arguments) {
      Buttons rb = new Buttons();
      rb.show();
   }
}

Adding to an Applet

Don't need a main() method, since the init() and start() methods are automatically called from the browser.

main() is automatically called when you launch an application from the command line.

Don't need a setSize() because this was specified in the HTML.

<4.8>

import javax.swing.*;

public class ButtonApplet extends JApplet {
   JButton abort = new JButton("Abort");
   JButton retry = new JButton("Retry");
   JButton fail = new JButton("Fail");

   public void init() {
      JPanel pane = new JPanel();
      pane.add(abort);
      pane.add(retry);
      pane.add(fail);
      setContentPane(pane);
   }
}

Common methods

setVisible(boolean) makes any component visible or invisible.

setEnabled(boolean) can disable a component. It doesn't make it invisible but does make it un-usable.

set/getText() for text components and set/getValue() for numeric components.

ImageIcons

Can get the image from a .gif or other graphics file.

Read into an ImageIcon object.

Book example:

<4.9>

import javax.swing.*;
public class Icons extends JFrame {
   JButton[] buttons = new JButton[24];
   public Icons() {
      super("Icons");
      setSize(335, 318);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      JPanel pane = new JPanel();
      ImageIcon icon = new ImageIcon("3dman.gif");
      for (int i = 0; i < 24; i++) {
         buttons[i] = new JButton(icon);
         pane.add(buttons[i]);
      }
      setContentPane(pane);
      show();
      }
   public static void main(String[] arguments) {
      Icons ike = new Icons();
      }
   }

Labels & Text Fields

Labels

Not editable

<4.10>

JLabel tinker = new JLabel("Tinker", SwingConstants.LEFT);

JLabel evers = new JLabel("Evers");

Text Fields

Editable

<4.11>

JTextField name = new JTextField(30);

JTextField name = new JTextField("Tomaso Alberto", 30);

to get a user-entered value, use getText().

For password masking, use JPasswordField

Book example: a user input form

<4.12>

import javax.swing.*;
public class Form extends javax.swing.JFrame {
   JTextField username = new JTextField(15);
   JPasswordField password = new JPasswordField(15);
   JTextArea comments = new JTextArea(4, 15);
   public Form() {
      super("Feedback Form");
      setSize(260, 160);
      setDefaultCloseOperation(EXIT_ON_CLOSE);
      JPanel pane = new JPanel();
      JLabel usernameLabel = new JLabel("Username: ");
      JLabel passwordLabel = new JLabel("Password: ");
      JLabel commentsLabel = new JLabel("Comments:");
      comments.setLineWrap(true);
      comments.setWrapStyleWord(true);
      pane.add(usernameLabel);
      pane.add(username);
      pane.add(passwordLabel);
      pane.add(password);
      pane.add(commentsLabel);
      pane.add(comments);
      setContentPane(pane);
      show();
   }
   public static void main(String[] arguments) {
      Form input = new Form();
   }
}

Check Boxes & Radio Buttons

Check boxes are boolean true/false input

Radio buttons are for choosing among several alternatives

Use a nongraphical ButtonGroup object to group them together as one logical unit.

book example:

<4.13>

import javax.swing.*;
public class ChooseTeam extends JFrame {
   JRadioButton[] teams = new JRadioButton[4];
   public ChooseTeam() {
      super("Choose Team");
      setSize(140, 190);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      teams[0] = new JRadioButton("Colorado");
      teams[1] = new JRadioButton("Dallas", true);
      teams[2] = new JRadioButton("New Jersey");
      teams[3] = new JRadioButton("Philadelphia");
      JPanel pane = new JPanel();
      ButtonGroup group = new ButtonGroup();
      for (int i = 0; i < teams.length; i++) {
         group.add(teams[i]);
         pane.add(teams[i]);
      }
      setContentPane(pane);
      show();
   }
   public static void main(String[] arguments) {
      ChooseTeam ct = new ChooseTeam();
   }
}

Drop-down Lists & Combo Boxes

Use the same component, JComboBox for both

For a combo box, the component remains visible on the page. For a drop-down list, the component only becomes visible when needed.

book example:

<4.14>

import javax.swing.*;
public class Expiration extends JFrame {
   JComboBox monthBox = new JComboBox();
   JComboBox yearBox = new JComboBox();

   public Expiration() {
      super("Expiration Date");
      setSize(220, 90);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      JPanel pane = new JPanel();
      JLabel exp = new JLabel("Expiration Date:");
      pane.add(exp);
      for (int i = 1; i < 13; i++)
      monthBox.addItem("" + i);
      for (int i = 2000; i < 2010; i++)
      yearBox.addItem("" + i);
      pane.add(monthBox);
      pane.add(yearBox);
      setContentPane(pane);
      show();
   }
   public static void main(String[] arguments) {
      Expiration ct = new Expiration();
   }
}