Swing II - Absolute Java - page 1029

All of the classes JButton, JMenuItem, and JLabel have constructors that let you
specify text and an icon to appear on the button, menu item, or label. The constructor
can specify no text or icon, text only, an icon only, or both text and an icon. When you
specify both text and an icon, the text is the first argument and the icon is the second
argument; also, the constructor for a JLabel requires a third argument, as described in
Display 18.5. If you omit either text or an icon (or both) from the constructor, you can
add them later with the methods setText and setIcon. Some of these methods for
the classes JButton, JMenuItem, and Jlabel are given in Display 18.5 .

Icons and the Class ImageIcon

An icon is simply a small picture, although it is not really required to be small. The class
ImageIcon is used to convert a picture file to a Swing icon.
SYNTAX
ImageIcon Name_Of_ImageIcon =
new ImageIcon(Picture_File_Name);

The Picture_File_Name is a string giving either a relative or absolute path name to the
picture file. (So if the picture file is in the same directory as your program, you need give
only the name of the picture file.)
EXAMPLE
ImageIcon happyIcon =
new ImageIcon("smiley.gif");

Display 18.5 Some Methods in the Classes JButton , JMenuItem , and JLabel (part 1 of 2)

public JButton()
public JMenuItem()
public JLabel()

Creates a button, menu item, or label with no text or icon on it. (Typically, you will later use
setText and/or setIcon with the button, menu item, or label.)

public JButton(String text)
public JMenuItem(String text)
public JLabel(String text)

Creates a button, menu item, or label with the text on it.

public JButton(ImageIcon picture)
public JMenuItem(ImageIcon picture)
public JLabel(ImageIcon picture)

Creates a button, menu item, or label with the icon picture on it and no text.

(continued)