英文:
Contents of JScrollPane are not visible
问题
public class Main {
public static void main(String[] args) {
JFrame frame = new JFrame("Hex");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent inputs = new InputPanel();
JComponent hexGrid = new HexGridPanel(10, 10, 30);
JComponent outputs = new OutputPanel();
JComponent toolbar = new ToolbarPanel(); // This one is having problems
Container pane = frame.getContentPane();
pane.add(inputs, BorderLayout.LINE_START);
pane.add(hexGrid, BorderLayout.CENTER);
pane.add(outputs, BorderLayout.LINE_END);
pane.add(toolbar, BorderLayout.PAGE_END); // This one is having problems
frame.pack();
frame.setVisible(true);
}
}
public ToolbarPanel() {
JPanel content = new JPanel();
content.setLayout(new BoxLayout(content, BoxLayout.X_AXIS));
ButtonGroup buttonGroup = new ButtonGroup();
JRadioButton button = new JRadioButton("Test");
buttonGroup.add(button);
content.add(button);
JScrollPane scroll = new JScrollPane(content);
scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_NEVER);
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
content.setBorder(new LineBorder(Color.RED));
scroll.setBorder(new LineBorder(Color.GREEN));
this.add(scroll);
this.setPreferredSize(new Dimension(900, 200));
this.setBorder(new LineBorder(Color.BLACK)); // Only this is showing up in the UI
}
The ToolbarPanel itself shows up, but not the scroll pane or the radio buttons. It should show up inside the black rectangle at the bottom of this image.
英文:
I have a main class:
public class Main {
public static void main(String[] args) {
JFrame frame = new JFrame("Hex");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent inputs = new InputPanel();
JComponent hexGrid = new HexGridPanel(10,10,30);
JComponent outputs = new OutputPanel();
JComponent toolbar = new ToolbarPanel(); // This one is having problems
Container pane = frame.getContentPane();
pane.add(inputs, BorderLayout.LINE_START);
pane.add(hexGrid, BorderLayout.CENTER);
pane.add(outputs, BorderLayout.LINE_END);
pane.add(toolbar, BorderLayout.PAGE_END); // This one is having problems
frame.pack();
frame.setVisible(true);
}
}
And all of my other panels work except for ToolbarPanel that for some reason does not show its content:
public ToolbarPanel(){
JPanel content = new JPanel();
content.setLayout(new BoxLayout(content, BoxLayout.X_AXIS));
ButtonGroup buttonGroup = new ButtonGroup();
JRadioButton button = new JRadioButton("Test");
buttonGroup.add(button );
content.add(button );
JScrollPane scroll = new JScrollPane(content);
scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_NEVER);
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
content.setBorder(new LineBorder(Color.RED));
scroll.setBorder(new LineBorder(Color.GREEN));
this.add(scroll);
this.setPreferredSize(new Dimension(900, 200));
this.setBorder(new LineBorder(Color.BLACK)); // Only this is showing up in the UI
}
The ToolbarPanel itself shows up, but not the scroll pane or the radio buttons. It should show up inside of the black rectangle at the bottom of this image:
答案1
得分: 1
好的，以下是您要翻译的内容：
嗯，您没有包含一个 MRE（最小可复现示例），我也没有看到您的类的声明，但我猜您正在使用：
public class ToolbarPanel extends JComponent
问题是，默认情况下，JComponent 没有布局管理器，因此您看不到您的组件。
如果您使用：
public class ToolbarPanel extends JPanel
情况会稍微好一些，但所有组件都会显示在一个小正方形中。
因此，您还需要在构造函数中添加
setLayout( new BorderLayout() );
注意：
这就是为什么每个问题都应该包含一个最小可复现示例，我们不应该花时间猜测您可能正在做什么的原因。
英文:
Well, you didn't include a MRE and I don't see the declaration of your class but I'm guessing you are using:
public class ToolbarPanel extends JComponent
The problem is that by default a JComponent doesn't have a layout manager so you won't see your components.
If you use:
public class ToolbarPanel extends JPanel
It will be a little better, but all the components will be displayed in a small square.
So you will also want to add
setLayout( new BorderLayout() );
to your constructor.
Note:
This is why a minimal reproducible example should be included with every question. We should not have to spend time guessing what you may or may not be doing.
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