Creating buttons with for loop in Java

Question

I am making a map over the highest mountains in europe and want to create a for loop that makes the actions for the buttons for me.

I am currently stuck at this code:

String Text = "btn" + i;
        Text.addSelectionListener(new SelectionAdapter()

I want to add:

btn1.addSelectionListener(new SelectionAdapter()

btn2.addSelectionListener(new SelectionAdapter()

btn3.addSelectionListener(new SelectionAdapter()

btn4.....

when running the for loop. Does anyone know how to do this?

 for(final int i=1; i< country.length; i++){
        String Text = "btn" + i;
        Text.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {

                txtCountry= new Text(shell, SWT.BORDER);
                txtCountry.setText("Country: " + country[i]);
                txtCountry.setBounds(22, 112, 204, 30);
                formToolkit.adapt(txtCountry, true, true);

                txtHighestMountain = new Text(shell, SWT.BORDER);
                txtHighestMountain.setText("Highest Mountain: " + highestPoint[i]);
                txtHighestMountain.setBounds(22, 148, 204, 30);
                formToolkit.adapt(txtHighestMountain, true, true);

                txtMeters = new Text(shell, SWT.BORDER);
                txtMeters.setText("Meters above sea level: " + MAMSL[i]);
                txtMeters.setBounds(22, 184, 204, 30);
                formToolkit.adapt(txtMeters, true, true);
                }
}

I am getting the following error: The method addSelectionListener(new SelectionAdapter(){}) is undefined for the type String — HRS
– HRS, Commented Dec 18, 2015 at 11:28

Mohammed Aouf Zouag · Accepted Answer · 2015-12-18 11:47:41Z

1

Create an array of buttons:

Button[] btnArr = new Button[] {
    btn1, btn2, btn3,...
}

& loop through it:

for(int i = 0; i < btnArr.length; i++) {
    btnArr[i].addSelectionListener(new SelectionAdapter()....)
}

Plus, to optimize your code, consider creating a custom SelectionListener.

edited Dec 18, 2015 at 11:47

answered Dec 18, 2015 at 11:26

Mohammed Aouf Zouag

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2 Comments

HRS Over a year ago

Thanks that looks like a good way to do it, however when trying to implement the array I get following error: btnArr cannot be resolved to a variable. Any suggestions here?

Mohammed Aouf Zouag Over a year ago

You have to declare it. Check my edit. Button[] btnArr = new ...

Jordi Castilla · Accepted Answer · 2015-12-18 11:35:21Z

1

To achieve your first goal, just create a List with the buttons, and insert SelectionAdapter in each iteration.

List<Button> buttons = // fill the list

for (Button b : buttons) {
    b.addSelectionListener(new SelectionAdapter() {....});
}

edited Dec 18, 2015 at 11:35

answered Dec 18, 2015 at 11:26

Jordi Castilla

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Comments

Propagandian · Accepted Answer · 2015-12-18 13:12:33Z

In your code, you are adding a SelectionListener to your String. You will need to add the listener to your Button.

Furthermore, the code can be streamlined a bit, such as having the SelectionListener in a dedicated method.

An example:

private Button[] getButtons() {
    Button[] buttons = new Button[country.length];

    for (final int i = 1; i < country.length; i++) {
        String text = "btn" + i;
        Button button = new Button(text);
        button.addSelectionListener(getCountrySelectionListener(country[i]));
        buttons[i] = button;
    }
    return buttons;
}

private SelectionListener getCountrySelectionListener(final String country) {
    return new SelectionAdapter() {
        public void widgetSelected(SelectionEvent e) {

            txtCountry = new Text(shell, SWT.BORDER);
            txtCountry.setText("Country: " + country);
            txtCountry.setBounds(22, 112, 204, 30);
            formToolkit.adapt(txtCountry, true, true);

            txtHighestMountain = new Text(shell, SWT.BORDER);
            txtHighestMountain.setText("Highest Mountain: " + highestPoint[i]);
            txtHighestMountain.setBounds(22, 148, 204, 30);
            formToolkit.adapt(txtHighestMountain, true, true);

            txtMeters = new Text(shell, SWT.BORDER);
            txtMeters.setText("Meters above sea level: " + MAMSL[i]);
            txtMeters.setBounds(22, 184, 204, 30);
            formToolkit.adapt(txtMeters, true, true);
        }
    }
}

This assumes the required variables and such is global. If not, you could always just pass them across as parameters, or create a Bean (Wrapper Object) for the related values, Such as a Country Bean.

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