Inheritance - Java Concepts - page 662

73 private JLabel resultLabel;
74 private JPanel panel;
57 private BankAccount account;
76
77 private static final int FRAME_WIDTH = 500 ;
78 private static final int FRAME_HEIGHT = 200 ;
79
80 private static final double DEFAULT_RATE =
5 ;
81 private static final double INITIAL_BALANCE
= 1000 ;
82 }

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S ELF C HECK

20. What happens if you omit the first JLabel object?

21. If a text field holds an integer, what expression do you use to read its
contents?

10.11 Text Areas

In Section 10.10 , you saw how to construct text fields. A text field holds a single line
of text. To display multiple lines of text, use the JTextArea class.

Use a JTextArea to show multiple lines of text.

When constructing a text area, you can specify the number of rows and columns:

final int ROWS = 10;
final int COLUMNS = 30;
JTextArea textArea = new JTextArea(ROWS, COLUMNS);

Use the setText method to set the text of a text field or text area. The append
method adds text to the end of a text area. Use newline characters to separate lines,
like this:

textArea.append(account.getBalance() + Ð\nÑ);

If you want to use a text field or text area for display purposes only, call the
setEditable method like this