GRAPHICAL USER INTERFACE (GUI) AND OBJECT-ORIENTED DESIGN (OOD) - Java Programming: From Problem Analysis to Program Design - page 347

JButton
To create a button, Java provides the class JButton . Thus, to create objects
belonging to the class JButton , we use a technique similar to the one we used to
create instances of JLabel and JTextField . Table 6-5 shows some methods of the
class JButton .

TABLE 6-5 Commonly Used Methods of the class JButton

Method / Description

public JButton(Icon ic)
//Constructor to initialize the button object with the icon
//specified by ic.

public JButton(String str)
//Constructor to initialize the button object to the text specified
//by str.

6

public JButton(String str, Icon ic)
//Constructor to initialize the button object to the text specified
//by str and the icon specified by ic.

public void setText(String str)
//Method to set the text of the button to the string specified by str.

public String getText()
//Method to return the text contained in the button.

public void addActionListener(ActionListener obj)
//Method to register a listener object to the button object.

The following three lines will create two buttons, Calculate and Exit , shown earlier in
Figure 6-2:
JButton calculateB, exitB;

//Line 1

calculateB = new JButton("Calculate"); //Line 2
exitB = new JButton("Exit"); //Line 3
The statement in Line 1 declares calculateB and exitB to be reference variables of
type JButton . The statement in Line 2 instantiates the button object calculateB
and sets the text for the button to the string Calculate . Similarly, the statement in
Line 3 instantiates the button object exitB and sets the text for exitB to the string
Exit .