从队列中显示JList，并在单击按钮后刷新

Question

i have a GUI that accepts an entry and then processes the data, but i want to be able to display the entries in a queue and then display them in a JList.

i have the GUI code with the JList and the queue but i dont know how to link them and make the JList a representation of the queue.

GUI Class:

public class ServerPlayergameMain extends javax.swing.JFrame implements Runnable {
   public serverPlayerQueue serverQueue = new serverPlayerQueue();

   Thread run;

   public ServerPlayergameMain() {
        initComponents();
    }

    public void run(){
        String commandMessage = command.getText();
         serverQueue.addToQueue(commandMessage);
        command.setText(" ");
        repaint();
        validate();
    }
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        command = new javax.swing.JTextField();
        jLabel1 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();
        jScrollPane1 = new javax.swing.JScrollPane();
        jList1 = new javax.swing.JList();
        jButton2 = new javax.swing.JButton();
        jButton3 = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setResizable(false);

        command.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                commandActionPerformed(evt);
            }
        });
        command.addKeyListener(new java.awt.event.KeyAdapter() {
            public void keyPressed(java.awt.event.KeyEvent evt) {
                commandKeyPressed(evt);
            }
        });

        jLabel1.setText("Enter your command:");

        jButton1.setText("Go!");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jList1.setModel(new javax.swing.AbstractListModel() {
            String[] strings = { "Item 1", "Item 2", "Item 3", "Item 4", "Item 5" };
            public int getSize() { return strings.length; }
            public Object getElementAt(int i) { return strings[i]; }
        });
        jScrollPane1.setViewportView(jList1);

        jButton2.setText("Save");

        jButton3.setText("Forfeit");

        jLabel2.setText("Command Queue:");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(29, 29, 29)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jButton3)
                        .addGap(0, 0, Short.MAX_VALUE))
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jLabel1)
                                .addGap(0, 132, Short.MAX_VALUE))
                            .addComponent(command))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jButton2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(jScrollPane1)
                            .addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, 88, Short.MAX_VALUE)
                            .addComponent(jButton1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                        .addGap(38, 38, 38))))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(90, 90, 90)
                        .addComponent(jLabel2)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 253, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jButton2)
                        .addGap(18, 18, 18)
                        .addComponent(jButton1)
                        .addGap(0, 46, Short.MAX_VALUE))
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(jLabel1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(command, javax.swing.GroupLayout.PREFERRED_SIZE, 42, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addGap(12, 12, 12)
                        .addComponent(jButton3)))
                .addContainerGap())
        );

        pack();
    }
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
     run = new Thread(this);
     run.start();
}                                        
    private javax.swing.JTextField command;
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JList jList1;
    private javax.swing.JScrollPane jScrollPane1;
}

queue class:

public class serverPlayerQueue {
        String [] elementArray = new String [20];
        int frontPointer = 0;
        int rearPointer = -1;
        int arrayInput = 0;
        char choice;

    public void addToQueue (String command) {
        if (arrayInput == 20) {
            System.out.println("Error in queue!");
        }else{
            rearPointer = rearPointer+1;
            rearPointer = rearPointer % 20;
            elementArray[rearPointer] = command;
            arrayInput++;
        }
    }
}

could you please help me make the JList get the data from the queue and then display it?

Thanks for your time

Answer 1

You have several choices, but which one you choose will depend on other factors...

You Could...

Simply add or remove an element to the underlying ListModel when you update the queue. This would require you to provide a ListModel which was capable of been mutated, such as a DefaultListModel .

This assumes that you are modifying the queue within the context of the Event Dispatching Thread

You Could...

Devise a wrapper/proxy class that was backed by the queue and provided the basic functionality you need (add/remove) but also provide listener support.

In this way, you could notifications when elements were added or removed from the queue to those parties that are interested.

This allows the queue to be managed in a separate thread and places the responsibility of ensure that updates to the UI occur within the listener itself

This is basically a implementation of a Observer Pattern

Either way, take a look at How to Use Lists for more details