使用Java Swing删除选定的复选框

Question

I am new to java swing. I have a code that generates checkboxes. I want to have a button somewhere in my frame, which on clicking, should delete the selected checkbox entries. Here is what I have so far.

public class Scroll extends JPanel  {  


public static void main(String[] args) {   
     SwingUtilities.invokeLater(new Runnable(){  
         public void run()    {  
             createAndShowGUI();   
             }   
         });   
     }   
 public static void createAndShowGUI()     {  
     JFrame frame = new JFrame("JFrame with ScrollBar"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
     JComponent newContentPane = new ResultButtonBar();
     newContentPane.setOpaque(true);
     JScrollPane scrollPane = new JScrollPane(newContentPane); 
     scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);  
     frame.getContentPane().add(scrollPane);  
     frame.setSize(800, 800); 
     frame.setVisible(true);
     JButton startButton = new JButton("Start");
     frame.add(startButton, BorderLayout.SOUTH);
     startButton.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent arg0) {
            // TODO Auto-generated method stub

            JOptionPane.showMessageDialog(null, "basdsadad");

                }
        });

    }

  } 

and the new ResultButtonBar().java

public class ResultButtonBar extends JPanel  {   

  private HashMap<JCheckBox, ArrayList<Integer>> map = new HashMap<>();
    private JLabel _label;

    private static final int MAX_CHECKS = 1000;

    public ResultButtonBar() {
        super();

        JButton btn = new JButton();
        btn.setVisible(true);

        JCheckBox checkBox;
        Random r = new Random();

        JPanel checkPanel = new JPanel(new GridLayout(0, 1));
        _label = new JLabel("You selected nothing");
        checkPanel.add(_label);

        for (int i = 0; i < MAX_CHECKS; i++) {
            StringBuilder sb = new StringBuilder();
            ArrayList<Integer> a = new ArrayList<>();
            for (int j = 0; j < 2; j++) {
                Integer temp = (r.nextInt()) % 100;
                a.add(temp);
                sb.append(temp).append(" ");
            }

            checkBox = new JCheckBox(sb.toString().trim());
            checkBox.setName("CheckBox" + i);

            map.put(checkBox, a);
            checkPanel.add(checkBox);
        }

        add(checkPanel);

    }

}

Answer 1

First of all, keep all your check boxes in an ArrayList so you will have a reference to them when you need it.

Then, add a JButton wherever you need. Then iterate over this ArrayList and call invalidate() on the component which contains your check boxes. Next statement would be to call the remove() method on the container; the checkPanel .

Alternatively, you may call removeAll() if all the components in the container are check boxes and you want to remove them.

The alternative pointed by StanislavL is also a good one if you have a lot of different components along with check boxes

Answer 2

I can think of two approaches:

• if You are maintaining one JPanel instance which contains only the instances of JCheckBox , then you can first get all the checkbox's using panel.getComponents() method, check their selection state and depending on the state remove it by calling panel.remove(component) . For example:

   Component checkBox[] = checkBoxPanel.getComponents(); for(Component c:checkBox) if(((JCheckBox)c).isSelected()) checkBoxPanel.remove(c); checkBoxPanel.revalidate(); checkBoxPanel.repaint(); 

  The last call revalidate() and repaint() on the checkBoxPanel is important for reflecting changes on the layout and graphics rendering of the components.

• You can use ItemListener with the instances of JCheckBox to do things on selection state change. Use an instance of ArrayList<JCheckBox> to add the selected checkBox to the list. However you should use an implemented ItemListener: MyItemListener implements ItemListener and create one instance and add this instances to all the checkboxes to react on state change. You can use event source e.getSource() to get the JCheckBox instance on which the ItemEvent is performed.

Tutorial resource:

1. How to Write an Item Listener