Java JCombobox导致渲染问题
您好，我遇到以下问题：
public class TestCombo extends JFrame{
public TestCombo() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(200,200);
setVisible(true);
setLayout(new BorderLayout());
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(2,4));
JLabel l1 = new JLabel("test1");
JLabel l2 = new JLabel("test2");
panel.add(l1);
panel.add(l2);
// JComboBox<String> combo = new JComboBox<String>();// <-- uncomment this for the problem
this.add(panel, BorderLayout.NORTH);
}
public static void main(String[] args) {
new TestCombo();
}
}
如您所见，我正在做一个非常简单的示例。如果我取消注释标记的部分，则不会显示标签项。如果我调整窗口大小，它们会再次可见。这里奇怪的是，我什至没有将组合添加到面板或任何地方。我只是实例化它。 有人可以告诉我为什么需要调整框架大小才能看到标签吗？我做错了什么吗？
Hello, I have the following problem:
public class TestCombo extends JFrame{
public TestCombo() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(200,200);
setVisible(true);
setLayout(new BorderLayout());
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(2,4));
JLabel l1 = new JLabel("test1");
JLabel l2 = new JLabel("test2");
panel.add(l1);
panel.add(l2);
// JComboBox<String> combo = new JComboBox<String>();// <-- uncomment this for the problem
this.add(panel, BorderLayout.NORTH);
}
public static void main(String[] args) {
new TestCombo();
}
}
As you can see, I am doing a very simple example. If I uncomment the marked part, the label items are not shown. If I resize the window, they are visible again. The strange thing here is that I do not even add the combo to the panel or anywhere. I am just instantiating it.
Can someone tell me why I need to resize the frame to see the labels? Am I doing something wrong?
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您从一开始就在执行
setVisible(true)。您应该在添加所有组件后执行此操作。
you are doing
setVisible(true)in the very beginning.You should do it after adding all components.
我认为这不是 JComboBox 的有效语法，
它应该是
setVisible(true);应该在this.add(panel, BorderLayout.NORTH);之后。如何使用组合框
I don't think this is valid syntax for JComboBox
it should be
Also
setVisible(true);should be afterthis.add(panel, BorderLayout.NORTH);.How to use comboBox