Core Swing Components - The Definitive Guide to Java Swing - page 87

Table 4-8. JLabel Properties (Continued)

Property Name Data Type Access

icon Icon Read-write bound

iconTextGap int Read-write bound

labelFor Component Read-write bound

text String Read-write bound

UI LabelUI Read-write

UIClassID String

Read-only

verticalAlignment int Read-write bound

verticalTextPosition int Read-write bound

The content of the JLabel is the text and its associated image. Displaying an image within
a JLabel will be discussed in the “Interface Icon” section later in this chapter. However, you can
display different icons, depending on whether the JLabel is enabled or disabled. By default, the
icon is a grayscaled version of the enabled icon, if the enabled icon comes from an Image object
( ImageIcon , as described later in the chapter). If the enabled icon doesn't come from an Image ,
there's no icon when JLabel is disabled, unless manually specified.
The position of the contents of the JLabel is described by four different properties:
horizontalAlignment , horizontalTextPosition , verticalAlignment , and verticalTextPosition .
The horizontalAlignment and verticalAlignment properties describe the position of the contents
of the JLabel within the container in which it's placed.

■ Note Alignments have an effect only if there's extra space for the layout manager to position the compo-
nent. If you're using a layout manager such as FlowLayout , which sizes components to their preferred size,
these settings will effectively be ignored.

The horizontal position can be any of the JLabel constants LEFT , RIGHT , or CENTER . The
vertical position can be TOP , BOTTOM , or CENTER . Figure 4-7 shows various alignment settings,
with the label reflecting the alignments.
The text position properties reflect where the text is positioned relative to the icon when
both are present. The properties can be set to the same constants as the alignment constants.
Figure 4-8 shows various text position settings, with each label reflecting the setting.

■ Note The constants for the different positions come from the SwingConstants interface that the

JLabel class implements.