【发布时间】：2021-03-24 14:27:12
【问题描述】：
我正在尝试将一些项目动态添加到 jpanel。我使用 gridbaglayout 作为这个 jpanel 的经理（下面是红色背景色），我想将面板及其项目垂直对齐到顶部。知道如何让这个面板进入面板顶部吗？
这是我的代码：
public class WebcamFrame extends JFrame implements Runnable {
private Webcam webcam;
private WebcamPanel webcamPanel;
private JLabel labelText;
private JPanel actionsPanel;
private boolean running;
private HashSet<String> cardsPlayed;
private final JPanel actionsContainer;
private final JPanel buttonsPanel;
private final GridBagConstraints constraints;
public WebcamFrame( Callback killWebcam, Callback handleSubmit ) {
running = true;
setLayout( new FlowLayout() );
setTitle( "Scan a card" );
setIconImage( new ImageIcon(getClass().getResource("/tslogo.png")).getImage() );
setDefaultCloseOperation( JFrame.DO_NOTHING_ON_CLOSE );
addWindowListener( new WindowAdapter() {
@Override
public void windowClosing( WindowEvent e ) {
super.windowClosing( e );
killWebcam.call();
}
} );
cardsPlayed = new HashSet<>();
Dimension size = WebcamResolution.QVGA.getSize();
webcam = Webcam.getDefault();
webcam.setViewSize( size );
webcamPanel = new WebcamPanel( webcam );
webcamPanel.setPreferredSize( size );
webcamPanel.setLayout( new BorderLayout() );
labelText = new JLabel( "", SwingConstants.CENTER );
if( Webcam.getDefault() == null ) labelText.setText( "No Webcam detected" );
actionsContainer = new JPanel( new BorderLayout() );
JButton confirmButton = new JButton( "Confirm Selection" );
confirmButton.addActionListener( e -> {
List<CardDataModel> cardsToSubmit = new ArrayList<>();
cardsPlayed.forEach( cardName -> {
CardDataModel card = new CardDataModel();
card.cardName = cardName;
cardsToSubmit.add( card );
} );
handleSubmit.call( cardsToSubmit );
} );
JButton clearButton = new JButton( "Clear Selection" );
buttonsPanel = new JPanel();
buttonsPanel.add( confirmButton );
buttonsPanel.add( clearButton );
buttonsPanel.setVisible( false );
constraints = new GridBagConstraints();
clearButton.addActionListener( e -> {
cardsPlayed.clear();
actionsPanel.removeAll();
constraints.gridy = 0;
actionsPanel.add( new JLabel( "Played Cards"), constraints );
actionsContainer.setVisible( false );
buttonsPanel.setVisible( false );
labelText.setVisible( false );
constraints.gridy = 0;
pack();
} );
JPanel subPanel = new JPanel();
subPanel.setLayout( new BorderLayout() );
subPanel.add( labelText, BorderLayout.NORTH );
subPanel.add( buttonsPanel, BorderLayout.SOUTH );
webcamPanel.add( subPanel, BorderLayout.SOUTH );
actionsPanel = new JPanel( new GridBagLayout() );
constraints.gridy = 0;
constraints.insets = new Insets( 0, 0, 5, 0 );
actionsPanel.add( new JLabel( "Played Cards"), constraints );
actionsPanel.setBackground(Color.red);
JScrollPane scrollPane = new JScrollPane( actionsPanel );
actionsContainer.add( scrollPane, BorderLayout.NORTH );
actionsContainer.setVisible( false );
add( webcamPanel );
add( actionsContainer );
pack();
setLocationRelativeTo( null );
setVisible( false );
setResizable( false );
}
@Override
public void run() {
do {
try {
Thread.sleep( 100 );
} catch( InterruptedException e ) {
e.printStackTrace();
}
Result result = null;
BufferedImage image;
// Only try to read qr code if webcam is open and frame is webCamFrame is visible
if( webcam.isOpen() && isVisible() ) {
if( (image = webcam.getImage()) == null ) {
continue;
}
LuminanceSource source = new BufferedImageLuminanceSource( image );
BinaryBitmap bitmap = new BinaryBitmap( new HybridBinarizer(source) );
try {
result = new MultiFormatReader().decode( bitmap );
} catch( NotFoundException e ) {
// fall through if there is no QR code in image
}
}
if( result != null ) {
String cardName = result.getText();
if( !cardsPlayed.contains( cardName ) ) {
labelText.setText( "Play card" + (cardsPlayed.size() > 0 ? "s" : "") + "?" );
cardsPlayed.add( cardName );
JPanel cardPlayedPanel = new JPanel( new GridLayout( 0, 1, 5, 5) );
cardPlayedPanel.setBorder( BorderFactory.createCompoundBorder(new LineBorder(Color.BLACK), new EmptyBorder(2, 2, 2, 2)) );
cardPlayedPanel.setOpaque( true );
cardPlayedPanel.setBackground( Color.LIGHT_GRAY );
cardPlayedPanel.add( new JLabel(cardName) );
constraints.gridy++;
actionsPanel.add(cardPlayedPanel, constraints );
actionsContainer.setVisible( true );
buttonsPanel.setVisible( true );
pack();
}
}
} while( running );
}
}
提前感谢您的帮助
【问题讨论】：
-
1) 为了尽快获得更好的帮助，edit 添加minimal reproducible example 或Short, Self Contained, Correct Example。布局问题不需要网络摄像头之类的东西。只需添加
JLabel即可。 2)GridLayout适用于单列组件。要将其置于面板顶部，请将网格布局面板添加到PAGE_START的BorderLayout。 -
把GridBagLayout JPanel放到FlowLayout JPanel里面，把FlowLayout JPanel放到JFrame上。
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@c0der 是的，我只接受能回答我问题的答案。没想到这是犯罪
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@Tamjid 没有意识到这是犯罪 - 是的，这是犯罪。如果人们花时间提供帮助并提供建议，那么您至少可以“接受”答案，或者回复 cmets 说明这些建议是否有帮助。你在这里得到帮助：stackoverflow.com/questions/65929527/… 和这里：stackoverflow.com/questions/66309992/…。我不知道你是否愿意阅读这些建议。如果您不感谢所提供的帮助，我们为什么要继续提供帮助？
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我没有说你可以“接受”评论。我建议您可以添加自己的评论以表明该建议是否有帮助。这样我们至少知道您花时间阅读评论并尝试建议。
标签： java swing layout-manager gridbaglayout