Question

I have a seemingly simple problem:

I want to create 7 check-boxes (for the days of the week) lined up on 1 line using a
horizontal field manager. Unfortunately a CheckboxField, by default, takes up the whole line. Due to this, CheckboxField SHOULD (and according to the javadoc it does) have a style setting that makes it use only the width it needs. However, my compiler (Eclipse Plug-In) does not recognize “CheckboxField.NO_USE_ALL_WIDTH” and doesn’t compile/package my app.

The CheckboxField declerations:

private CheckboxField   cf_sun,
                        cf_mon,
                        cf_tue,
                        cf_wed,
                        cf_thu,
                        cf_fri,
                        cf_sat;

I defined my checkboxes as follows:

cf_sun = new CheckboxField("Sun", false, CheckboxField.NO_USE_ALL_WIDTH); // <-- ERROR
        cf_mon = new CheckboxField("Mon", false);
        cf_tue = new CheckboxField("Tue", false);
        cf_wed = new CheckboxField("Wed", false);
        cf_thu = new CheckboxField("Thu", false);
        cf_fri = new CheckboxField("Fri", false);
        cf_sat = new CheckboxField("Sat", false);

How could I make this work?

Answer 1

According to the BlackBerry Javadocs on CheckboxField:

NO_USE_ALL_WIDTH

public static final long NO_USE_ALL_WIDTH

Use this style to indicate
the field should use only as much horizontal space as necessary.

See Also: Constant Field Values

Since: BlackBerry API 7.0.0

Are you building your app against the SDK 7.0 libraries? Or something lower? If you use lower than 7.0, then the compiler (rightly) won’t find that new constant.

Anyway, I tried your code on OS 5.0, and CheckboxField did not take up the whole line, if you add them all to a HorizontalFieldManager. But, let’s say that you do need more control over the field width …

Luckily, it looks like you have a pretty simple layout. All your fields labels are the same length (3 chars), so you can probably just create a new subclass that sets the width. If you want it to be more dynamic, then you could use Font.getAdvance() on the checkbox labels to determine exactly how wide each label is, and therefore, exactly how much space each field would need (accounting for the width of the checkbox, too, of course).

private class MyCheckboxField extends CheckboxField {

  public MyCheckboxField(String label, boolean value) {
     super(label, value);
  }

  public int getPreferredWidth() {
     // 32 is just a constant to account for the checkbox itself ... 
     // ... make this whatever you like
     return getFont().getAdvance(getLabel()) + 32;
  }

  protected void layout(int width, int height) {
     super.layout(getPreferredWidth(), height);
     setExtent(getPreferredWidth(), getPreferredHeight());
  }

}

and then

cf_mon = new MyCheckboxField("Mon", false);