Graphical User Interfaces - Building Java Programs: A Back to Basics Approach - page 826

Table 14.4 Useful Properties of All Components (Including JFrames )

Property Type Description Methods

background Background color

Color getBackground,

setBackground(Color)

enabled Whether the component can be

boolean isEnabled,

interacted with

setEnabled(boolean)

focusable Whether the keyboard can send

boolean isFocusable,

input to the component

setFocusable(boolean)

font Font used to write text

Font getFont, setFont(Font)

foreground Foreground color

Color getForeground,

setForeground(Color)

location ( x , y ) coordinate of component's

Point getLocation,

top-left corner

setLocation(Point)

size Current width and height of the

Dimension getSize,

component

setSize(Dimension)

preferred size “Preferred” width and height of

Dimension getPreferredSize,

the component; the size it should

setPreferredSize(Dimension)

be to make it appear naturally on
the screen (used with layout
managers, seen later)

visible Whether the component can be

boolean isVisible,

seen on the screen

setVisible(boolean)

It turns out that all graphical components and frames share a common set of
properties, because they exist in a common inheritance hierarchy. The Swing GUI
framework is a powerful example of the code sharing of inheritance, since many
components share features represented in common superclasses. Table 14.4 lists
several useful common properties of frames/components and their respective
methods.
Several of the properties in Table 14.4 are objects. The background and fore-
ground properties are Color objects, which you may have seen previously in
Supplement 3G. The location property is a Point object; the Point class was dis-
cussed in Chapter 8. The font property is a Font object; we'll discuss fonts later in
this chapter. All of these types are found in the java.awt package, so be sure to
import it, just as you did when you were drawing graphical programs with
DrawingPanel in previous chapters:

import java.awt.*; // for various graphical objects

The size property is an object of type Dimension , which simply stores a width
and height and is constructed with two integers representing those values. We'll use
this property several times in this chapter. We only need to know a bit about the