Prohibit the Use of Methods from Superclasses

A couple of days ago, I saw an interesting way to prohibit the use of a method from a superclass. A coworker of mine wrote a subclass of a JTextField that should display a date in a specific fashion. Before you comment the obvious: Yes, there where reasons not to use JFormattedTextField. ;)

Here’s how he wrote the new class:

public class CustomDateField extends JTextField {

	public void setDate(Date date) {
		Calendar c = new GregorianCalendar();
		c.setTime(date);
        // the real method was a bit more complicated, but for the example that is sufficient
		super.setText(String.valueOf(c.get(Calendar.YEAR)));
	}
 
	/**
	 * @deprecated Use setDate(Date date) instead
	 */
	@Deprecated
	@Override
	public void setText(String arg0) {
		throw new RuntimeException(
				"This method is not supported. Use setDate(Date date) instead.");
	}
}

Because the new textfield should only work with java.util.Date, the common setText() is rendered unusable. Therefore, a new method is offered. The class works as follows:

public class CustomDateFieldTest {

	CustomDateField field;
 
	@Before
	public void before() {
		field = new CustomDateField();
	}
 
	@Test(expected = RuntimeException.class)
	public void setTextDoesntWorkAnymore() {
		field.setText("Text");
	}
 
	@Test
	public void setDateWorks() {
		Date date = new Date();
		field.setDate(date);
		assertEquals("field.getText()", "2013", field.getText());
	}
}

Because I’ve never seen this combination of @Deprecated and throwing an exception before, I want to record it here.