CODEWITHSUNDEEP
javawhile-loopcomboboxswtlistener
Zach C
Zach C

Reputation: 21

Java Listener for looped combo in Eclipse SWT

I have a Java SWT GUI that I've built using Eclipse. I'm using a while loop to reference a text file. The while loop iterates through each line of the text file and builds a series of combo or text boxes for specific items on each line. Each line represents one visual column in the GUI and, depending on how many items I have in the text file, the GUI builds to the right. For simplicity's sake I am including just the code that I am trying to figure out.

For instance, assume I have three lines that create six combo boxes in the GUI (three columns by two rows). I would like a change on the top row in the second column to execute a Listener on the bottom row, also in the second column. However, right now the Listener loops through all of the combo's and makes a change to all three, not just the one I want. I can't figure out how to make this work. See the code below. I appreciate the help.

private void buildMultipleSatPulldowns() {
    try {
        FileReader fr = new FileReader("MultipleSatellites.txt");
        BufferedReader br = new BufferedReader(fr);

        String line = null;
        String[] tempS;
        String constellation = null;
        String satellite = null;

        while ((line = br.readLine()) != null) {
            tempS = line.split("~");
            constellation = tempS[4];
            satellite = tempS[6];

            constNameCombo = new Combo(satellitesComposite2, SWT.NONE);
            constNameCombo.setToolTipText("Pulldown constellation name");
            constNameCombo.setBounds(startX + x2, 71, 125, 28);
            constNameCombo.setItems(constNameArray);
            constNameCombo.setText(constellation);
            constNameCombos.add(constNameCombo);

            constNameCombo.addModifyListener(new ModifyListener() { // captures changed combo values
                public void modifyText(ModifyEvent arg0) {
                    setConstellationPD();
                }
            });

            sPullDown(constellation); // builds the satellite array for the constellation and populates each pulldown

            satNameCombo = new Combo(satellitesComposite2, SWT.NONE);
            satNameCombo.setToolTipText("Pulldown satellite name");
            satNameCombo.setBounds(startX + x2, 106, 125, 28);
            satNameCombo.setItems(satNameArray);
            satNameCombo.setText(satellite);
            satNameCombos.add(satNameCombo);

            startX = startX + nextX;

        }

        br.close();

    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

private void setConstellationPD() {

    int constellations = 0;

    for (Combo constNameCombo : constNameCombos) {

        // What do I do here so that only the desired satNameCombo changes to reflect the desired pull down?

        setSatellitesPD(constellations, constNameCombo)

        constellations++;
    }

}

private void setSatellitesPD(int c, String cN) {
    int satellites = 0;

    for (Combo satNameCombo : satNameCombos) {
        if (c == satellites) {
            satNameCombo.setText(satNameCombos.get(satellites).toString());
            satNameCombo.removeAll();
            sPullDown(cN);
            satNameCombo.setText("select Satellite");
        }
        satellites++;
    }

}

private void sPullDown(String cName) {
    // sPullDown takes the constellation name and returns a String Array of all objects in the constellation. This code works correctly when called.
}

Upvotes: 0

Views: 194

Answers (1)

Loris Securo
Loris Securo

Reputation: 7638

If I understood correctly, you need a way to know which combo fired the event in order to affect some other components.

SWT events like ModifyEvent have the method getSource() which will return the object on which the event occurred.

Having that you just need to properly identify it; for example you could simply use constNameCombos.indexOf(eventCombo) to retrieve its index.

Or, more efficiently, you could attach some data to your combos with the method setData and retrieve it inside the event with getData, for example inside the loop:

// "i" would be the index of the combo
constNameCombo.setData("index", i);
i++;

and in the event:

Combo eventCombo = (Combo) arg0.getSource();
int index = eventCombo.getData("index");

With these information you should be able to identify the other components that you want to change.

Upvotes: 2

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