我有一个带有一些选项的 JComboBox。当我在另一个组件上进行选择时，我正在更改 JComboBox 的内容。首先我调用removeAllItems()方法，然后将我现在需要的Strings一一添加。
问题是，默认情况下我有一些选项，其中一个是较大的文本，因此 JComboBox 获得了正确显示该选项所需的宽度。当我更改 JComboBox 内容时，该文本选项消失了，现在一个较小的文本为 JComboBox 提供了宽度，因此当我更改内容时，它变得更小。
我的第一种方法是调用myComboBox.setPreferredSize(myComboBox.getSize())，然后它的尺寸是固定的，但不正确：它的高度和宽度变得有点小。我认为这是因为我使用的是 Nimbus Look&Feel，而我从该getSize()方法中获得的维度是 Java 默认 Look%Feel 给出的维度。
我也尝试myCombo.setPreferredSize(new Dimension(myCombo.getHeight(), myCombo.getWidth()))了相同的结果。
我该如何解决这个问题？
我添加了一个如何使用布局的代码示例：
private String[] comboEventDOutputStrings = { "Run", "Stop", "Pause", "Conditioning time", "Deposition time", "Equilibration time", "Measurement time"};
private String[] comboEventDInputStrings = { "Run", "Stop", "Pause"};
// The first String array is the default set of values. It's obvious that the JComboBox will get smaller
// when I change to the second array of contents
//...
JPanel pane = new JPanel(new GridBagLayout());
JPanel jPanelExterno = new JPanel(new GridBagLayout());
GridBagConstraints cExterna = new GridBagConstraints();
GridBagConstraints c = new GridBagConstraints();
Border loweredetched = BorderFactory.createEtchedBorder(EtchedBorder.LOWERED);
jPanelExterno.setBorder(loweredetched);
jPanelExterno.setName("");
cExterna.fill = GridBagConstraints.BOTH;
cExterna.anchor = GridBagConstraints.NORTH;
cExterna.gridx = 0;
cExterna.gridy = 0;
cExterna.insets = new Insets(10,10,5,5);
JPanel jPanel1 = new JPanel(new GridBagLayout());
jPanel1.setBorder(loweredetched);
jPanel1.setName("PIO 1");
jCheckBox1 = new JCheckBox("Enable");
jCheckBox1.setSelected(false);
jCheckBox1.setName("1");
jCheckBox1.addActionListener(new PIOCheckListener());
c.fill = GridBagConstraints.BOTH;
c.anchor = GridBagConstraints.NORTH;
c.gridx = 0;
c.gridy = 0;
c.insets = new Insets(10,5,10,10);
jPanel1.add(jCheckBox1, c);
c.gridy++;
c.insets = new Insets(5,10,5,5);
JLabel label1 = new JLabel("IO Type");
jPanel1.add(label1, c);
c.gridx++;
c.insets = new Insets(5,5,5,10);
combo1 = new JComboBox(comboIOTypeStrings);
combo1.setEnabled(false);
combo1.setSelectedIndex(0);
combo1.setName("1");
combo1.addActionListener (new PIOComboListener());
jPanel1.add(combo1, c);
c.gridy++;
c.insets = new Insets(5,10,5,5);
c.gridx=0;
JLabel label2 = new JLabel("Active level");
jPanel1.add(label2, c);
c.gridx++;
c.insets = new Insets(5,5,5,10);
combo2 = new JComboBox(comboActiveLevelStrings);
combo2.setEnabled(false);
combo2.setSelectedIndex(0);
jPanel1.add(combo2, c);
c.gridy++;
c.insets = new Insets(5,10,5,5);
c.gridx=0;
JLabel label3 = new JLabel("Event");
jPanel1.add(label3, c);
c.gridx++;
c.insets = new Insets(5,5,10,10);
combo3 = new JComboBox(comboEventDOutputStrings);
combo3.setEnabled(false);
combo3.setSelectedIndex(0);
jPanel1.add(combo3, c);
c.gridy++;
c.insets = new Insets(5,10,5,5);
c.gridx=0;
JLabel label4 = new JLabel("Node");
jPanel1.add(label4, c);
c.gridx++;
c.insets = new Insets(5,5,10,10);
combo4 = new JComboBox(comboNodeStrings);
combo4.setEnabled(false);
combo4.setSelectedIndex(0);
jPanel1.add(combo4, c);
jPanelExterno.add(jPanel1, cExterna);
pioDialog.add(pane);
pioDialog.pack();
pioDialog.setLocationRelativeTo(null);
pioDialog.setVisible(true);
//...
}
class PIOComboListener implements ActionListener{
@Override
public void actionPerformed(ActionEvent a) {
JComboBox cb = (JComboBox)a.getSource();
JComboBox target1 = null;
JComboBox target2 = null;
JComboBox target3 = null;
switch(Integer.parseInt(cb.getName())){
case 1:
target1 = combo2;
target2 = combo3;
target3 = combo4;
break;
default:
Register.debug("PIODialog error: No target for comboBoxes");
break;
}
if(cb.getSelectedIndex()==2){ //Analog input
target1.setEnabled(false);
target2.setEnabled(false);
target3.setEnabled(false);
}
else{
target1.setEnabled(true);
target2.setEnabled(true);
target3.setEnabled(true);
target2.removeAllItems();
if(cb.getSelectedIndex()==0){
for(int i=0; i<comboEventDOutputStrings.length; i++)
target2.addItem(comboEventDOutputStrings[i]);
} else {
for(int i=0; i<comboEventDInputStrings.length; i++)
target2.addItem(comboEventDInputStrings[i]);
}
}
}
}
它基本上是一个带有 6 个 JPanel 的 GridBagLayout，每个 JPanel 都有一个新的 GridBagLayout。我只是在这里写了 jPanel1 来简化事情。我希望它不是很乱。