Question

I’m trying to create a java GUI that outputs a value once the value is selected from a drop down and the apply button is pressed. The problem is this is my first time creating a GUI in java, I just used some sample code I found and reworked it, but I’m unsure how to output the value I want. The code is below and the value I want to output is “colour”.

package state;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GUI extends JFrame {

    Font font = new Font("Cambria", Font.PLAIN, 20);
    static final String Colour[] = {"Blue", "Yellow"};
    static final String Pitch[] = {"Main Pitch", "Side Pitch"};
    final static int maxGap = 20;
    JComboBox colourComboBox;
    JComboBox pitchComboBox;
    Label colourLabel;
    Label pitchLabel;
    JButton applyButton = new JButton("Apply settings");
    GridLayout experimentLayout = new GridLayout(0,2);

    public GUI(String name) {
        super(name);
        setResizable(false);
    }

    public void initGaps() {
        colourComboBox = new JComboBox(Colour);
        colourComboBox.setFont(font);
        pitchComboBox = new JComboBox(Pitch);
        pitchComboBox.setFont(font);

    }

    public void addComponentsToPane(final Container pane) {
        initGaps();
        final JPanel compsToExperiment = new JPanel();
        compsToExperiment.setLayout(experimentLayout);
        JPanel controls = new JPanel();
        controls.setLayout(new GridLayout(0,2));

        //Set up components preferred size
        JButton b = new JButton("Just fake button");
        Dimension buttonSize = b.getPreferredSize();
        compsToExperiment.setPreferredSize(new Dimension((int)(buttonSize.getWidth() * 3.3)+maxGap,
                (int)(buttonSize.getHeight() * 1.5)+maxGap * 5));


       //Add buttons to experiment with Grid Layout
        colourLabel = new Label("Select Robot Colour:");
        colourLabel.setFont(font);

        pitchLabel = new Label("Select Pitch:");
        pitchLabel.setFont(font);

        compsToExperiment.add(colourLabel);
        compsToExperiment.add(colourComboBox);
        compsToExperiment.add(pitchLabel);
        compsToExperiment.add(pitchComboBox);
        controls.add(applyButton);

        //Process the Apply gaps button press
        applyButton.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                String colour = (String)colourComboBox.getSelectedItem();
                String pitch = (String)pitchComboBox.getSelectedItem();

            }
        });
        pane.add(compsToExperiment, BorderLayout.NORTH);
        pane.add(new JSeparator(), BorderLayout.CENTER);
        pane.add(controls, BorderLayout.SOUTH);
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method is invoked from the
     * event dispatch thread.
     */
    private static void createAndShowGUI() {
        //Create and set up the window.
        GUI frame = new GUI("Match Conditions");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //Set up the content pane.
        frame.addComponentsToPane(frame.getContentPane());
        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        /* Use an appropriate Look and Feel */
        try {
            //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
            UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
        } catch (UnsupportedLookAndFeelException ex) {
            ex.printStackTrace();
        } catch (IllegalAccessException ex) {
            ex.printStackTrace();
        } catch (InstantiationException ex) {
            ex.printStackTrace();
        } catch (ClassNotFoundException ex) {
            ex.printStackTrace();
        }
        /* Turn off metal's use of bold fonts */
        UIManager.put("swing.boldMetal", Boolean.FALSE);

        //Schedule a job for the event dispatch thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

Answer 1

You can get the text using the getSelectedItem() function in JComboBox.

ex.

pitchComboBox.getSelectedItem().toString()
colourComboBox.getSelectedItem().toString()