Swing I - Absolute Java - page 999

a JTextField or JTextArea than is specified in its size, but the extra text may not
be visible.
The number of characters per line and the number of lines are a guaranteed minimum.
More lines and especially more characters per line may be visible. (The space per line is
actually guaranteed to be Characters_Per_Line times the space for one uppercase letter M.)
SYNTAX
JTextField Name_of_Text_Field = new JTextField( Characters_Per_Line );
JTextArea Name_of_Text_Area =
new JTextArea( Number_of_Lines , Characters_Per_Line );
EXAMPLES
JTextField name = new JTextField(30);
JTextArea someText = new JTextArea(10, 30);
There are also constructors that take an additional String argument that specifies an initial
string to display in the text component.
SYNTAX
JTextField Name_of_Text_Field =
new JTextField( Initial_String , Characters_Per_Line ) ;
JTextArea Name_of_Text_Area =
new JTextArea( Initial_String , Number_of_Lines , Characters_Per_Line ) ;
EXAMPLES
JTextField name = new JTextField("Enter name here.", 30);
JTextArea someText =
new JTextArea("Enter story here.\nClick button.", 10, 30);
Number of Characters per Line
The number of characters per line (given as an argument to constructors for JTextField
or JTextArea ) is not the number of just any characters. The number gives the number of
em spaces in the line. An em space is the space needed to hold one uppercase letter M,
which is the widest letter in the alphabet. So a line that is specified to hold 20 characters
will always be able to hold at least 20 characters and will almost always hold more than
20 characters.
Scroll Bars
Scroll bars for text areas and text fields are discussed in Chapter 18. They are a nice touch,
but until you reach Chapter 18, your GUI programs will work fine without them.