Re: Simple question about Java Methods

Nigel Wade <>
Tue, 19 Aug 2008 09:52:52 +0100
Mark Space wrote:

Danger_Duck wrote:

Alright, maybe someone can tell me how to do this with enums:

I have a combo-box (I'm using Eclipse, so
org.eclipse.swt.widgets.Combo.Combo) that contains the elements "Sin",
"Square", and "Sawtooth".

Based on the selection, I want to create a different function. This
was the original reason I was using public static final Strings
instead of enums: since the Combo.getText() method returns a String, I

I don't know SWT, but strings are easy to deal with:

   Waves ws = Waves.valueOf("sine");

would get you the enum from the string, and:

   Waves w = Waves.valueOf( combobox1.getText() );

Would do the same thing based on the code you have. (I changed the name
from a class to a variable because even though I don't know SWT I'm
pretty sure getText() is not a static method.)

Stefan is right, there's a better way besides a switch statement to do
actually draw the waveform. However, if you don't feel confortable yet
with adding methods to a Java enum, switch will work fine until you do.
  Just be aware that there are other ways, and resolve to come back and
revist it when you feel more comfortable with Java.

was just going to hardwire selections as public static final Strings
in my FunctionGenerator class

ie, FunctionGenerator fg = new
FunctionGenerator(combobox1.getText(), ...);
and I would perform a check of matching strings....crude I know.

  FunctionGenerator fg = new
       FunctionGenerator( Waves.valueOf( combobox1.getText() ) );

Why use Strings in the JComboBox? Enums can do pretty much all the work for you.

You can use any Object, including Enums (Waves in this case), in a JComboBox.
JComboBox uses an Object's toString() method to display the text in the visual
component. Rather than using the JComboBox.getText() method use the
getSelectedItem() and you get back the selected Waves item that you actually

If you capitalize the Waves:
 public enum Waves { Sine, Square, Sawtooth; }

the capitalized strings will be displayed in the JComboBox.

 JComboBox box;
 private void jComboBoxActionPerformed(java.awt.event.ActionEvent evt) {
    JComboBox box = (JComboBox) evt.getSource();
    Waves selectedWave = (Waves) box.getSelectedItem();
    System.out.println("Selected waveform is : "+selectedWave);
    FunctionGenerator fg = new FunctionGenerator( selectedWave }

Nigel Wade

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