Java Reference
In-Depth Information
public TempConversion()
{
setTitle("Temperature Conversion");
setSize(WIDTH, HEIGHT);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible( true );
}
public static void main(String[] args)
{
TempConversion tempConv = new TempConversion();
}
}
Now you need to access the container content pane to place the GUI components
and set the required layout of the pane. Therefore, as before, you need the following
statements:
Container c = getContentPane();
//get the container
c.setLayout( new GridLayout(1, 4)); //create a new layout
c.add(celsiusLabel); //add the label celsiusLabel
//to the container
c.add(celsiusTF); //add the text field celsiusTF
//to the container
c.add(fahrenheitLabel); //add the label fahrenheitLabel
//to the container
c.add(fahrenheitTF); //add the text field fahrenheitTF
//to the container
You want your program to respond to the events generated by JTextFields .
Just as when you click a JButton an action event is generated, when you press
Enter in a JTextField , it generates an action event. Therefore, to register
event listeners with JTextFields , we use the four steps outlined in the section
Handling an Event earlier in this chapter: (1) create a class that implements the
interface ActionListener ; (2) provide the definition of the method
actionPerformed within the class that you created in Step 1; (3) create and
instantiate an object of the class created in Step 1; and (4) register the event
handler created in Step 3 with the object that generates an action event using the
method addActionListener .
Next, we create and register an action listener with the JTextField celsiusTF .
First we create the class CelsHandler , implementing the interface
ActionListener . Then, we provide the definition of the method
actionPerformed of the class CelsHandler . When the user enters the tempera-
ture in the JTextField celsiusTF and presses Enter , the program needs to
calculate
and
display
the
equivalent
temperature
in
the
JTextField
 
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