在jlabel中显示选定的jcheckbox

Question

i have 10 jcheckbox and only 5 should be selected. i already did all the coding for this one, but i don't know how to display the selected 5 into a jlabel. i tried doing it by this code:

           JCheckBox check;
           JPanel panel=new JPanel();
           for(int i=0; i<10; i++){
                check=new JCheckBox();
                check.addActionListener(listener);
                check.setName("Select"+i);

                panel.add(check); 
            }

this is the listener

ActionListener listener = new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            check = (JCheckBox) e.getSource();
            name=check.getName();
        }
    };

and this is the panel where it should be displayed into jlabel

        panel2=new JPanel(new GridLayout(5,1));
        for(int i=0; i<5; i++){
            txtVote=new JLabel(name);
            panel2.add(txtVote);
        }

but using this code, it doesn't display anything on the jlabel. if i change the listener into this:

ActionListener listener = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                check = (JCheckBox) e.getSource();
                txtVote.setText(check.getName());
            }
        };

it will only display into the last label. other jlabels would be blank. please help thank you so much

EDIT

here is the code that is runnable

public class JCheckBoxtoLabel{
    JCheckBox check;
    String name;
    JLabel txtVote;

     public JCheckBoxtoLabel() {
            JFrame frame = new JFrame();
            JPanel panel = createPanel();
            JPanel panel2 = panel2();

            frame.setLayout(new GridLayout(1,2));
            frame.add(panel); frame.add(panel2);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setSize(500, 300);
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
        }

        private JPanel createPanel() {
               JPanel panel=new JPanel(new GridLayout(10,1));
               for(int i=0; i<10; i++){
                    check=new JCheckBox();
                    check.addActionListener(listener);
                    check.setName("Select"+i);

                    panel.add(check); 
                }

            return panel;
        }

        private JPanel panel2(){
            JPanel panel2=new JPanel(new GridLayout(5,1));
            for(int i=0; i<5; i++){
                txtVote=new JLabel();
                txtVote.setBorder(BorderFactory.createLineBorder(Color.RED));
                panel2.add(txtVote);
            }
         return panel2;
     }

        ActionListener listener = new ActionListener() {
            @Override   
            public void actionPerformed(ActionEvent e) {
                check = (JCheckBox) e.getSource();
                txtVote.setText(check.getName());
            }
        };

        public static void main(String[] args) {
            SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    new JCheckBoxtoLabel();
                }
            });
        }
}

Answer 1

Consider changing what you're doing and displaying the text in a JList and not in JLabels. This can help you consolidate your information. You can also give your JCheckBoxes or JRadioButtons and ItemListener that only allows 5 of the buttons to be selected at a time -- unselecting the oldest one currently selected. For instance:

import java.awt.GridLayout;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;

@SuppressWarnings("serial")
public class FiveNames extends JPanel {
    private static final String[] ALL_NAMES = {"Bob", "Bill", "Frank", "Helen", 
            "Erica", "Mickey", "Donald", "Hillary", "Michael", "Peter", "Roger"};
    private static final int ALLOWED_SELECTIONS_COUNT = 5;
    private DefaultListModel<String> displayListModel = new DefaultListModel<>();
    private JList<String> list = new JList<>(displayListModel);

    public FiveNames() {
        JPanel namePanel = new JPanel(new GridLayout(0, 1, 0, 5));
        RButtonItemListener rButtonListener = new RButtonItemListener();
        for (String name : ALL_NAMES) {
            JRadioButton rButton = new JRadioButton(name);
            rButton.setActionCommand(name);
            rButton.addItemListener(rButtonListener);
            namePanel.add(rButton);
        }

        list.setVisibleRowCount(ALLOWED_SELECTIONS_COUNT);
        list.setPrototypeCellValue("                            ");
        list.setBackground(null);

        setLayout(new GridLayout(1, 0));
        add(namePanel);
        add(list);
    }

    // listener to only allow the last 5 radiobuttons to be selected
    private class RButtonItemListener implements ItemListener {
        private List<ButtonModel> buttonModelList = new ArrayList<>();

        @Override
        public void itemStateChanged(ItemEvent e) {
            JRadioButton rBtn = (JRadioButton) e.getSource();
            ButtonModel model = rBtn.getModel();
            if (e.getStateChange() == ItemEvent.SELECTED) {
                buttonModelList.add(model);
                if (buttonModelList.size() > ALLOWED_SELECTIONS_COUNT) {
                    for (int i = 0; i < buttonModelList.size() - ALLOWED_SELECTIONS_COUNT; i++) {
                        ButtonModel removedModel = buttonModelList.remove(0);
                        removedModel.setSelected(false);
                    }
                }
            } else {
                buttonModelList.remove(model);
            }
            displayListModel.clear();
            for (ButtonModel buttonModel : buttonModelList) {
                displayListModel.addElement(buttonModel.getActionCommand());
            }
        }

    }

    private static void createAndShowGui() {
        JFrame frame = new JFrame("FiveNames");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new FiveNames());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

Answer 2

The problem is that txtVote is only a single Jlabel and you are trying to use it for all 5. Since the fifth jlabel was the last to be created it is the one being used. My suggestion is that you create an arraylist field and inside panel12 add each label to the arraylist. Then inside the listener it would iterate through each jlabel in the arraylist check if has text set to it, if so check the next one until it finds one with no text, then sets the text to that. The problem with this at the moment is that in your code you are never defining what happens when they uncheck the box.

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;

import javax.swing.BorderFactory;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class JCheckBoxtoLabel{
JCheckBox check;
String name;
JLabel txtVote;
ArrayList<JLabel> boxLabels;

public JCheckBoxtoLabel() {
    boxLabels = new ArrayList<JLabel>();

    JFrame frame = new JFrame();
    JPanel panel = createPanel();
    JPanel panel2 = panel2();

    frame.setLayout(new GridLayout(1,2));
    frame.add(panel); frame.add(panel2);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(500, 300);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}

private JPanel createPanel() {
    JPanel panel=new JPanel(new GridLayout(10,1));
    for(int i=0; i<10; i++){
        check=new JCheckBox();
        check.addActionListener(listener);
        check.setName("Select"+i);

        panel.add(check); 
    }

    return panel;
}

private JPanel panel2(){
    JPanel panel2=new JPanel(new GridLayout(5,1));
    for(int i=0; i<5; i++){
        txtVote=new JLabel();
        txtVote.setBorder(BorderFactory.createLineBorder(Color.RED));
        panel2.add(txtVote);
        boxLabels.add(txtVote);
    }
    return panel2;
}

ActionListener listener = new ActionListener() {
    @Override   
    public void actionPerformed(ActionEvent e) {
        check = (JCheckBox) e.getSource();
        if(!check.isSelected()){
            for(JLabel label: boxLabels){
                if(label.getText().equals(check.getName())) label.setText("");
            }
        }else{
            for(JLabel label: boxLabels){
                if(label.getText().isEmpty()){
                    label.setText(check.getName());
                    return;
                }
            }
        }
    }
};

public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            new JCheckBoxtoLabel();
        }
    });
}
}

Answer 3

Your variable JLabel txtVote is a single JLabel object, not an array.

In your panel2() function you assign 5 new JLabels to txtVote . Since you assign 5 in a row, it gets overriden each time so it only ever contains the final JLabel.

private JPanel panel2(){
         JPanel panel2=new JPanel(new GridLayout(5,1));
         for(int i=0; i<5; i++){
             txtVote=new JLabel();
             txtVote.setBorder(BorderFactory.createLineBorder(Color.RED));
             panel2.add(txtVote);
         }
         return panel2;
}

So when you call getText on voteTxt in the action listener, you are only getting the last labels text.

To fix this, you need to make txtVote an array of JLabels, and in your action listener iterate a second time through your JLabels and call get text on each in turn.

ActionListener listener = new ActionListener() {
    @Override   
    public void actionPerformed(ActionEvent e) {
        check = (JCheckBox) e.getSource();
        for (int i = 0; i < txtVotes.length; i++) {
            txtVotes[i].getText(check.getName());
        }
    }
};

I don't know if you realise or want to, but each label is being set to the same value, if you don't want this you will need to store an array of check names somewhere and iterate through these as well.