调整JFrame的大小，同时相应地缩小滚动窗格

Question

I currently have a JFrame to start fullscreen, inside this jframe i have a jpanel, this jpanel includes a vertical scrollpane. Now if i resize my jframe vertically it just kinda removes the bottom part of the jpanel. Is there any way to just shrink the jscrollpane.

Answer 1

im currently using flowlayout for the jframe,

Scrollbar appear automatically when the preferred size of the components added to the scroll pane area greater than the size of the scroll pane.

The FlowLayout will wrap components to a new row, but it always gives the preferred size as the size required to fit the components on a single row, so the preferred height will never change.

To solve this problem you can use the Wrap Layout which simple extend FlowLayout to recalculate the preferred size when wrapping occurs.

Answer 2

The JPanel consists of 3 other panels, a top panel, a scrollpane in the middle and a botpanel. The top and bot panel are just button and checkboxes and stuff

private void initPane() {
    createFolderCompPanel();
    createBotPanel();
    createTopPanel();
    createScrollPane();
    createTotalPanel();
    add(totalPanel);
}

private void createFolderCompPanel() {
    //Create folderCompPanel
    folderCompPanel = new JPanel();
    folderCompPanel.setLayout(new BoxLayout(folderCompPanel, BoxLayout.Y_AXIS));
    folderCompPanel.add(Box.createVerticalGlue());
}

private void createTotalPanel() {
    //Create TotalPanel
    totalPanel = new JPanel();
    totalPanel.setLayout(new BoxLayout(totalPanel, BoxLayout.Y_AXIS));
    totalPanel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
    totalPanel.add(topPanel);
    totalPanel.add(scrollPane);
    totalPanel.add(botPanel);
}

private void createScrollPane() {
    //Create ScrollPane
    scrollPane = new JScrollPane();
    scrollPane.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
    scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
    scrollPane.setViewportBorder(BorderFactory.createEtchedBorder());
    scrollPane.getVerticalScrollBar().setUnitIncrement(6);

}

private void createBotPanel() {
    //Create BotPanel
    botPanel = new JPanel();
    botPanel.setLayout(new BoxLayout(botPanel, BoxLayout.X_AXIS));

    //AddButton
    addButton = new JButton("Add");
    addButton.setEnabled(false);
    addButton.addActionListener(this);

    //SaveButton
    saveButton = new JButton("Save");
    saveButton.setEnabled(false);
    saveButton.addActionListener(this);

    //CancelButton
    cancelButton = new JButton("Cancel");
    cancelButton.setEnabled(false);
    cancelButton.addActionListener(this);

    lblTotalLength = new JLabel("Total Length: " + totalLength);
    botPanel.add(Box.createRigidArea(new Dimension(10, 0)));
    botPanel.add(addButton);
    botPanel.add(Box.createRigidArea(new Dimension(10, 0)));
    botPanel.add(lblTotalLength);
    botPanel.add(Box.createHorizontalGlue());
    botPanel.add(saveButton);
    botPanel.add(Box.createRigidArea(new Dimension(10, 0)));
    botPanel.add(cancelButton);
    botPanel.add(Box.createRigidArea(new Dimension(10, 0)));

}

private void createTopPanel() {
    //Create TopPanel
    topPanel = new JPanel();
    topPanel.setLayout(new BoxLayout(topPanel, BoxLayout.X_AXIS));

    //create deletedisplay button
    deleteDisplayButton = new JButton("Delete Display");
    deleteDisplayButton.addActionListener(this);
    deleteDisplayButton.setEnabled(false);

    //create displaybox
    displayBox = new JComboBox();
    displayBox.addActionListener(this);
    displayBox.addItem("<None>");
    for (String s : connect.getAllDisplays()) {
        displayBox.addItem(s);
    }
    displayBox.setMaximumSize(displayBox.getPreferredSize());

    //create newdisplay button
    newDisplayButton = new JButton("New Display");
    newDisplayButton.addActionListener(this);

    topPanel.add(Box.createRigidArea(new Dimension(10, 0)));
    topPanel.add(displayBox);
    topPanel.add(Box.createHorizontalGlue());
    topPanel.add(newDisplayButton);
    topPanel.add(Box.createRigidArea(new Dimension(5, 0)));
    topPanel.add(deleteDisplayButton);
    topPanel.add(Box.createRigidArea(new Dimension(10, 0)));
}

this is the panel i add to the jframe

public GuiConstructor(){
    super(APPLICATION_NAME);
    this.setExtendedState(JFrame.MAXIMIZED_BOTH);
    this.setMinimumSize(new Dimension(630, 600));
    setLayout(new FlowLayout(FlowLayout.LEFT));
    LoopControlWindow folderSearch = new LoopControlWindow(connect, this);
    add(folderSearch);
    pack();
    setLocationRelativeTo(null);
    setResizable(true);
    setVisible(true);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}