# Java: Summary - Basic GUI Components

Components share many common methods, for example:
|  | cmp.requestFocus(); | Puts focus (eg, blinking cursor) in field, select button, etc.
|  | cmp.setFont(f); | Sets font.
JLabel - For fixed text.
| lbl = | new JLabel(t) | Creates JLabel with text t on it.
| lbl = | new JLabel(t, align) | Align text JLabel.LEFT, JLabel.CENTER, or JLabel.RIGHT.
| lbl = | new JLabel(icon) | Displays icon (eg, ImageIcon).
| lbl = | new JLabel(icon, align) | Align icon to JLabel.LEFT, JLabel.CENTER, or JLabel.RIGHT.
JTextField - Box containing one line of text.
| tf = | new JTextField(n); | Creates textfield n characters wide.
| s = | tf.getText(); | Returns string in textfield.
|  | tf.setText(s); | Sets text to s.
|  | tf.addActionListener(lst); | Action listener lst will be called if enter typed.
|  | tf.setEditable(bool); | Don't allow user to edit text field used for output.
|  | tf.setHorizontalAlignment(align); | `JTextField.LEFT` (default), `JTextField.CENTER`, or `JTextField.RIGHT`
JButton - Standard clickable button.
| btn = | new JButton(t); | Creates button with text t.
| btn = | new JButton(img); | Creates button with icon img.
| btn = | new JButton(t, img); | Creates button with both text and icon.
|  | btn.addActionListener(actlstnr); | Action listener actlstnr called when button clicked.
|  | btn.setEnabled(bool); | Used to enable/disable button.
JTextArea - Box containing multiple lines of text separated by '\n'.
| ta = | new JTextArea(rows, cols); | Creates textarea with specifed number of rows and columns.
| s = | ta.getText(); | Returns string in text area.
|  | ta.setText(s); | Sets text to s.
|  | ta.append(s); | Adds s to end of existing text.
|  | ta.insert(s, pos); | Inserts s at position pos.
|  | ta.setEditable(bool); | Don't allow user to edit textarea if used for output.
|  | ta.setLineWrap(bool); | Allow/disallow long lines to wrap.
|  | ta.setWrapStyleWord(bool); | Call `setLineWrap(true)` first. true wraps at word boundaries, false (default) at characters.
|  | ta.setBorder(brdr); | Add space between text and edge. Eg, to add 4 pixels use brdr ``BorderFactory.createEmptyBorder(4,4,4,4)
JCheckBox - Check box followed by text. Use either listener or check with isSelected().
| cb = | new JCheckBox(text); | Creates check box initially unchecked.
| cb = | new JCheckBox(text, bool); | Creates check box with checked state tf.
| b = | cb.isSelected(); | Returns bool if box is checked/unchecked.
|  | cb.setSelected(bool); | Sets checked state to tf.
|  | cb.addActionListener(actlstnr); | Adds ActionListener, which is called whenever user clicks.
|  | cb.setEnabled(bool); | Used to enable/disable check box.

Copyleft 2007 Fred Swartz