java - 将元素添加到 JPanel 但它们不显示

Question

我一直在尝试在 JPanel 中添加一组复杂的元素，根据返回的列数对它们进行布局 - 并在单击按钮时生成的新面板中显示它

我做错了什么，但无法弄清楚它是什么。替换标题面板中的其他文本元素绝对没问题，但看不出为什么我生成的代码没有被添加到面板中(或者更有可能 - 面板没有以可访问的方式显示)

            My JPanel output code - 
            private JPanel getOutput() throws BadIdent {

    short[] HDformats = { HDformat, Audformat };
    short[] SDformats = { SDformat, Audformat };
    List poolInfo;
    List freeSpaceHD = null;
    List freeSpaceSD = null;
    System.out.println(man.getZoneNumberName());
    // System.out.println(man.getPoolInfo());
    poolInfo = man.getPoolInfo();
    List poolSpace = man.getPoolSpace();
    if ((Short) HDformat != null) {
        freeSpaceHD = man.getFreeSpace(HDformats);
    }
    if ((Short) SDformat != null) {
        freeSpaceSD = man.getFreeSpace(SDformats);
    }
    JPanel content_panel = new JPanel(new GridLayout(poolInfo.size(), 4));
    JLabel[] PoolInfoLabel = new JLabel[poolInfo.size()];
    JLabel[] PoolSpaceLabel = new JLabel[poolInfo.size()];
    JLabel[] PoolSpaceHDLabel = new JLabel[poolInfo.size()];
    JLabel[] PoolSpaceSDLabel = new JLabel[poolInfo.size()];
    JPanel[] PoolInfo = new JPanel[poolInfo.size()];
    // GridBagConstraints gbc_lblPoolInfo[] = new
    // GridBagConstraints[poolInfo
    // .size()];
    // JLabel[] PoolInfoLabel = new JLabel[poolInfo.size()];
    for (int i = 0; i < poolInfo.size(); i++) {
        PoolInfoLabel[i] = new JLabel();
        PoolSpaceLabel[i] = new JLabel();
        PoolSpaceHDLabel[i] = new JLabel();
        PoolSpaceSDLabel[i] = new JLabel();
        PoolInfoLabel[i].setText((String) poolInfo.get(i));
        System.out.println(poolInfo.get(i));
        PoolSpaceLabel[i].setText((String) poolSpace.get(i));
        PoolSpaceHDLabel[i].setText((String) freeSpaceHD.get(i));
        PoolSpaceSDLabel[i].setText((String) freeSpaceSD.get(i));

        //
        // System.out.println(PoolInfoLabel[i].getText());

    }
    for (int i = 0; i < PoolInfoLabel.length; i++) {
        PoolInfo[i] = new JPanel();
        PoolInfo[i].add(PoolInfoLabel[i]);
        PoolInfo[i].add(PoolSpaceLabel[i]);
        PoolInfo[i].add(PoolSpaceHDLabel[i]);
        PoolInfo[i].add(PoolSpaceSDLabel[i]);
        System.out.println(PoolSpaceLabel[i].getText());
        System.out.println(PoolSpaceSDLabel[i].getText());
        System.out.println(PoolSpaceHDLabel[i].getText());
    }
    for (int i = 0; i < PoolInfo.length; i++) {
        content_panel.add(PoolInfo[i]);
    }
    return content_panel;
}

在面板和框架中添加和更改元素的按钮代码(框架是主要显示，面板是标题，位于 NORTH 边框布局中。三个组合框已添加并正确显示，我使用与在 getOutput() 函数中使用的机制大致相同的机制来生成和显示它们

    JButton ButtonSubmit = new JButton("Connect");
    ButtonSubmit.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            try {
                man.ManagerConnect(ISAHostName.getText(), null);
                // System.out.println(man.getZoneNumberName());
                ZoneNumName.setText(man.getZoneNumberName());
                AudFormat = getAudCombo();
                HDVidFormat = getHDCombo();
                SDVidFormat = getSDCombo();
                panel.add(HDVidFormat, gbc_HDVidFormat);
                panel.add(SDVidFormat, gbc_SDVidFormat);
                panel.add(AudFormat, gbc_AudFormat);
                btnFormatButton.setEnabled(true);
                frame.repaint();

            } catch (Exception e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        }

    });
    panel.add(ButtonSubmit, gbc_ButtonSubmit);
    btnFormatButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            try {
                JPanel content_panel = getOutput();
                frame.getContentPane().add(content_panel,
                        BorderLayout.CENTER);
            } catch (BadIdent e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
        }

    });
    panel.add(btnFormatButton, gbc_btnNewButton);

供引用 - 获取高清格式组合框

private JPanel getHDCombo() {
    JComboBox combo = new JComboBox();
    combo.setFont(new Font("Tahoma", Font.PLAIN, 10));
    combo.setMaximumRowCount(10);
    final Map<String, Integer> map = man.HDVidFormats();
    Collection<String> keys = map.keySet();
    Iterator<String> it = keys.iterator();
    while (it.hasNext()) {
        String key = it.next();
        combo.addItem(key);
    }
    combo.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            JComboBox combo = (JComboBox) e.getSource();
            String key = (String) combo.getSelectedItem();
            int format = map.get(key);
            System.out.println(format);
            HDformat = (short) format;
        }
    });
    JPanel panel = new JPanel();
    panel.setBackground(new Color(0, 0, 0, 0));
    panel.add(combo);
    return panel;
}

我确定这很简单，但老实说我不明白为什么没有添加面板为代码道歉——我已经有几年没有用 Java 从头开始​​编写任何 GUI 代码了

Answer 1

使用 frame.setLayout(null); 将布局设​​置为 null;

按照 MadProgrammer 所说的去做

Try adding frame.getContentPane().invalidate();, frame.getContentPane().validate(); and frame.getContentPane().repaint() after frame.getContentPane().add(content_panel, BorderLayout.CENTER) – MadProgrammer Aug 29 at 0:42

关于你的第二个问题，这样添加

frame.add(*jpanel here*, BorderLayout.CENTER);
*jpanel*.setBounds(width,height,x,y); //check up on this one. i think the param might be backwards

设置的边界应将您的 jpanel 移动到该位置并根据高度和宽度设置其边界。