ConversionPanelpublic class ConversionPanel extends Panel implements ActionListener, AdjustmentListener, ItemListener
| Fields Summary |
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| TextField | textField | | Choice | unitChooser | | Scrollbar | slider | | int | max | | int | block | | Converter | controller | | Unit[] | units |
| Constructors Summary |
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ConversionPanel(Converter myController, String myTitle, Unit[] myUnits)
//Initialize this ConversionPanel to use a GridBagLayout.
GridBagConstraints c = new GridBagConstraints();
GridBagLayout gridbag = new GridBagLayout();
setLayout(gridbag);
//Save arguments in instance variables.
controller = myController;
units = myUnits;
//Set up default layout constraints.
c.fill = GridBagConstraints.HORIZONTAL;
//Add the label. It displays this panel's title, centered.
Label label = new Label(myTitle, Label.CENTER);
c.gridwidth = GridBagConstraints.REMAINDER; //It ends a row.
gridbag.setConstraints(label, c);
add(label);
//Add the text field. It initially displays "0" and needs
//to be at least 10 columns wide.
textField = new TextField("0", 10);
c.weightx = 1.0; //Use maximum horizontal space...
c.gridwidth = 1; //The default value.
gridbag.setConstraints(textField, c);
add(textField);
textField.addActionListener(this);
//Add the pop-up list (Choice).
unitChooser = new Choice();
for (int i = 0; i < units.length; i++) { //Populate it.
unitChooser.add(units[i].description);
}
c.weightx = 0.0; //The default value.
c.gridwidth = GridBagConstraints.REMAINDER; //End a row.
gridbag.setConstraints(unitChooser, c);
add(unitChooser);
unitChooser.addItemListener(this);
//Add the slider. It's horizontal, and it has the maximum
//value specified by the instance variable max. Its initial
//and minimum values are the default (0). A click increments
//the value by block units.
slider = new Scrollbar(Scrollbar.HORIZONTAL);
slider.setMaximum(max + 10);
slider.setBlockIncrement(block);
c.gridwidth = 1; //The default value.
gridbag.setConstraints(slider, c);
add(slider);
slider.addAdjustmentListener(this);
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| Methods Summary |
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| public void | actionPerformed(java.awt.event.ActionEvent e)
setSliderValue(getValue());
controller.convert(this);
| | public void | adjustmentValueChanged(java.awt.event.AdjustmentEvent e)Respond to the slider.
textField.setText(String.valueOf(e.getValue()));
controller.convert(this);
| | public java.awt.Insets | getInsets()Puts a little breathing space between
the panel and its contents, which lets us draw a box
in the paint() method.
We add more pixels to the right, to work around a
Choice bug.
return new Insets(5,5,5,8);
| | double | getMultiplier()Returns the multiplier (units/meter) for the currently
selected unit of measurement.
int i = unitChooser.getSelectedIndex();
return units[i].multiplier;
| | double | getValue()Gets the current value in the text field.
It's guaranteed to be the same as the value
in the scroller (subject to rounding, of course).
double f;
try {
f = (double)Double.valueOf(textField.getText()).doubleValue();
} catch (java.lang.NumberFormatException e) {
f = 0.0;
}
return f;
| | public void | itemStateChanged(java.awt.event.ItemEvent e)
controller.convert(this);
| | public void | paint(java.awt.Graphics g)Draws a box around this panel.
Dimension d = getSize();
g.drawRect(0,0, d.width - 1, d.height - 1);
| | void | setSliderValue(double f)Set the slider value.
int sliderValue = (int)f;
if (sliderValue > max)
sliderValue = max;
if (sliderValue < 0)
sliderValue = 0;
slider.setValue(sliderValue);
| | void | setValue(double f)Set the values in the slider and text field.
setSliderValue(f);
textField.setText(String.valueOf((float)f));
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