Output with JTextArea

Context

You want to display several lines of text in an applet or graphical application, perhaps to test a class or to give information to the user. Then use a JTextArea.

Example

package W04.TextInApplet;
import javax.swing.JPanel;
import javax.swing.JTextArea;

public class DisplayText extends JPanel
{  private JTextArea ta = new JTextArea(20, 40);

   public DisplayText()
   {  this.getContentFrame().add(ta);
      ta.append("Here's my message!\n");
   }
}

Pattern

package <packagename>;
import javax.swing.JFrame;
import javax.swing.JTextArea;

public class <name-of-class> extends JFrame
{  private JTextArea <name-of-textarea> = new TextArea(<optional-size-info>);

   public <name-of-class>()
   {  this.add(<name-of-textarea>);
      <name-of-textarea>.append(<text-to-display>);
   }
}

Notes

• The "\n" causes a new line to be started in the JTextArea.
• It is also possible to get text from the user of the program via a JTextArea.
• Other useful operations:
  • Clear the JTextArea with ta.setText("");.
  • If the user shouldn't edit the contents of the JTextArea, use ta.setEditable(false);.
  • Set the colour of the text with ta.setForeground(Color.blue);. See the online documentation of the Color class for other colours.
• JTextFields provide similar functionality but for a single line of text.

Related Patterns

• Testing Classes sends output to System.out instead of putting it in an applet.
• Input with JButton and Input with JTextField also use JTextAreas for output.
• Summary of Listeners, for a summary of many standard gui widgets and the listeners they use.