JPanel＆组件自动更改位置

您好我正在挥杆应用程序，但我面临一个问题。

当我第一次运行应用程序JPanel被放置在适当的位置，我决定设置内部的组件。 但是，当发生问题

我最小化＆再次最大化框架窗口jpanel自动改变它的位置。

下面的图片显示了差异

正如我们可以看到第二个图像组件自动改变它的位置。

为此我写了下面的代码，

 jpanel_addPurchase = new JPanel(); jpanel_addPurchase.setLayout(null); jpanel_addPurchase.setBounds(400, 0, 500, 500); jpanel_addPurchase.setBackground(Color.white); JLabel lbl_title = new JLabel("Purchase Form"); lbl_title.setBounds(90, 20, 100, 100); jpanel_addPurchase.add(lbl_title); 

并在框架中添加此面板使用，

 setContentPane(getJPanel()); 

我哪里去错了？

Answer 1

我认为原始（非破损）的布局看起来古怪，并会使最终用户很难跟踪行和标签/字段。 我build议使用GroupLayout来alignment标签，并将包含值的字段alignment。 喜欢这个：

 import java.awt.*; import java.util.HashMap; import java.util.Map; import javax.swing.*; class TwoColumnLayoutWithHeader { /** * Provides a JPanel with two columns (labels & fields) laid out using * GroupLayout. The arrays must be of equal size. * * Typical fields would be single line textual/input components such as * JTextField, JPasswordField, JFormattedTextField, JSpinner, JComboBox, * JCheckBox.. & the multi-line components wrapped in a JScrollPane - * JTextArea or (at a stretch) JList or JTable. * * @param labels The first column contains labels. * @param fields The last column contains fields. * @param addMnemonics Add mnemonic by next available letter in label text. * @return JComponent A JPanel with two columns of the components provided. */ public static JComponent getTwoColumnLayout( JLabel[] labels, JComponent[] fields, boolean addMnemonics) { if (labels.length != fields.length) { String s = labels.length + " labels supplied for " + fields.length + " fields!"; throw new IllegalArgumentException(s); } JComponent panel = new JPanel(); GroupLayout layout = new GroupLayout(panel); panel.setLayout(layout); // Turn on automatically adding gaps between components layout.setAutoCreateGaps(true); // Create a sequential group for the horizontal axis. GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup(); GroupLayout.Group yLabelGroup = layout.createParallelGroup(GroupLayout.Alignment.TRAILING); hGroup.addGroup(yLabelGroup); GroupLayout.Group yFieldGroup = layout.createParallelGroup(); hGroup.addGroup(yFieldGroup); layout.setHorizontalGroup(hGroup); // Create a sequential group for the vertical axis. GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup(); layout.setVerticalGroup(vGroup); int p = GroupLayout.PREFERRED_SIZE; // add the components to the groups for (JLabel label : labels) { yLabelGroup.addComponent(label); } for (Component field : fields) { yFieldGroup.addComponent(field, p, p, p); } for (int ii = 0; ii < labels.length; ii++) { vGroup.addGroup(layout.createParallelGroup(). addComponent(labels[ii]). addComponent(fields[ii], p, p, p)); } if (addMnemonics) { addMnemonics(labels, fields); } return panel; } private final static void addMnemonics( JLabel[] labels, JComponent[] fields) { Map<Character, Object> m = new HashMap<Character, Object>(); for (int ii = 0; ii < labels.length; ii++) { labels[ii].setLabelFor(fields[ii]); String lwr = labels[ii].getText().toLowerCase(); for (int jj = 0; jj < lwr.length(); jj++) { char ch = lwr.charAt(jj); if (m.get(ch) == null && Character.isLetterOrDigit(ch)) { m.put(ch, ch); labels[ii].setDisplayedMnemonic(ch); break; } } } } /** * Provides a JPanel with two columns (labels & fields) laid out using * GroupLayout. The arrays must be of equal size. * * @param labelStrings Strings that will be used for labels. * @param fields The corresponding fields. * @return JComponent A JPanel with two columns of the components provided. */ public static JComponent getTwoColumnLayout( String[] labelStrings, JComponent[] fields) { JLabel[] labels = new JLabel[labelStrings.length]; for (int ii = 0; ii < labels.length; ii++) { labels[ii] = new JLabel(labelStrings[ii]); } return getTwoColumnLayout(labels, fields); } /** * Provides a JPanel with two columns (labels & fields) laid out using * GroupLayout. The arrays must be of equal size. * * @param labels The first column contains labels. * @param fields The last column contains fields. * @return JComponent A JPanel with two columns of the components provided. */ public static JComponent getTwoColumnLayout( JLabel[] labels, JComponent[] fields) { return getTwoColumnLayout(labels, fields, true); } public static String getProperty(String name) { return name + ": \t" + System.getProperty(name) + System.getProperty("line.separator"); } public static void main(String[] args) { Runnable r = new Runnable() { @Override public void run() { JComponent[] components = { new JTextField(15), new JTextField(10), new JTextField(8), new JSpinner(new SpinnerNumberModel(1,0,10,1)), new JSpinner(new SpinnerNumberModel(9.95,0d,100d,.01)), new JSpinner(new SpinnerNumberModel(9.95,0d,1000d,.01)), new JSpinner(new SpinnerNumberModel(9.95,0d,100d,.01)), new JSpinner(new SpinnerNumberModel(9.95,0d,1000d,.01)), new JSpinner(new SpinnerNumberModel(9.95,0d,100d,.01)), new JSpinner(new SpinnerNumberModel(9.95,0d,1000d,.01)) }; String[] labels = { "Product Name:", "Product Unit Name:", "Purchase Date:", "Quantity:", "Price Per Unit:", "Total Price:", "Discount:", "Total:", "VAT:", "Grand Total:" }; JComponent labelsAndFields = getTwoColumnLayout(labels,components); JComponent orderForm = new JPanel(new BorderLayout(5,5)); orderForm.add(new JLabel("Purchase Form", SwingConstants.CENTER), BorderLayout.PAGE_START); orderForm.add(labelsAndFields, BorderLayout.CENTER); JOptionPane.showMessageDialog(null, orderForm); } }; // Swing GUIs should be created and updated on the EDT // http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html SwingUtilities.invokeLater(r); } }