SWT: A Developer's Notebook

Using Radio-Style Buttons

Radio buttons are similar to Check buttons, except that only one button of a group of buttons may be selected at any given time. You use Radio buttons to enable the user to select one, and only one, of a group of options.

How do I do that?

You create Radio buttons simply by specifying the SWT.RADIO style:

final Button b1 = new Button(s, SWT.RADIO);
b1.setBounds(100,50,75,20);
b1.setText("Check Me");
final Button b2 = new Button(s, SWT.RADIO);
b2.setBounds(100,75,100,20);
b2.setText("No, Check Me");

Changing the ButtonExample code to include the preceding code will display Figure 6-3.

Figure 6-3. Radio buttons

What just happened?

In addition to the Radio button look and feel, you see that it is no longer possible to check both buttons at the same time. Checking one will cause the other to automatically become unchecked. For this reason, radio buttons must belong to a group. A group is all buttons with the RADIO style that are placed within the same container. In ButtonExample the container is a Shell, which means that all radio buttons placed on the shell belong to the same group and will share mutually exclusive selectability.

You may foresee a problem. What if you need to create two different groups to enable the user to specify one option from two sets of options? In this case, the solution is to place the buttons on two separate containers—Composites or