Develop Reference

Swing JScrollPane resizing to fit the viewport panel

I tried a lot of layout managers but none could solve my problem:
I want the items in a scrollPane to keep their size (preferred or minimum) and not being resized (reduced) to fit the viewport Panel. Since if it is a JTextArea, and if the text area has blank space and it is bigger then the viewport, it would reduce it so the blank text area won't be shown. I want the blank text area to be shown for appearance issues.
Im stacking one item after another using BoxLayout, and it seems to me that for text areas the setMinimum method fails.
If the text area has blank space, then the scrollbar of the ScrollPane won't appear, instead it only appears it there are no blank space left.
Any solution?
JScrollPane materialPane = new FScrollPane();
this.materialPaneView = new TPanel();
this.materialPaneView.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/2)));
this.materialPaneView.setLayout(new BoxLayout(this.materialPaneView, BoxLayout.Y_AXIS));
materialPane.setViewportView(materialPaneView);
materialPane.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/2)));
for(Material mat: this.unit.getMaterial()){
this.addMaterial(mat);
}
centerPanel.add(sectionPane);
centerPanel.add(exercisePane);
centerPanel.add(materialPane);
this.add(upperPanel, BorderLayout.NORTH);
this.add(centerPanel, BorderLayout.CENTER);
public void addMaterial(Material mat){
JTextField matName = new JTextField(30);
JPanel fieldButtonPanel = new TPanel();
fieldButtonPanel.setLayout(new GridLayout(1,2));
JPanel fieldPanel = new TPanel(new FlowLayout(FlowLayout.LEFT));
JPanel deleteMatButtonPanel = new TPanel(new FlowLayout(FlowLayout.RIGHT));
matName.setText(mat.getName());
matName.setMaximumSize(new Dimension(FFont.def.getSize()*20, 30));
fieldPanel.add(matName);
JButton deleteMat = new JButton("Delete Material");
deleteMatButtonPanel.add(deleteMat);
fieldButtonPanel.add(fieldPanel);
fieldButtonPanel.add(deleteMatButtonPanel);
fieldButtonPanel.setAlignmentX(LEFT_ALIGNMENT);
JTextArea matText = new FTextArea(mat.getDesc(), (int)(WIDTH*0.95), (int)(HEIGHT/3.4));
matText.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/3.5)));
/*matText.setMaximumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/3.4)));*/
matText.setText(mat.getDesc());
matText.setAlignmentX(LEFT_ALIGNMENT);
this.materialPaneView.add(fieldButtonPanel);
this.materialPaneView.add(matText);
matName.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
mat.setName(matName.getText());
}
});
HEIGHT and WIDTH are constants, and TPanel FScrollPane are my predefined transparent panels. The BoxLayout panel is the viewport of a scrollPane, and still, it would resize the text areas.

I am not sure i get what you are asking for so please tell me if i totally missed the point...
As far as i know the Viewport size is controlled by the component inside the JScrollPane and the JScrollPane size wont change no matter what happens to the viewport.
You either want to:
A) Resize the JScrollPane to the same size as it's content.
I would implement listeners to look for the content size change and resize the ScrollPane accordingly but you need to pay attention to resize the whole Hierarchy too.
B) You want to resize the viewport so that it fits in the JScrollPane? Y'know without scrollbars.
I had this problem and fixed it by using a ScrollablePanel component. Check this answer, follow the link to download the .class and use it to use a JPanel that resizes to fit the ScrollPane.
Those arent very detailed answers but i will need more information about what you are trying to do before expanding on it. And your code isnt complete, always share a code that we can CTRL+C/V and readily verify the problem in our end.

Java - JScrollPane Doesn't align with JTable

I am trying to make a JTable that has a width of 500. The problem is that the JScrollPane associated with the table doesn't appear next to the table.
Here is the relevant code:
// Create authorsPanel
JPanel authorsPanel = new JPanel(new BorderLayout(5,5));
authorsPanel.setBorder( new TitledBorder("Author Selection") );
// Configure author table
DefaultTableModel authorstableModel = new DefaultTableModel(new String[80][1], new String[]{"Authors"}) {
#Override
public boolean isCellEditable(int row, int column) {
//all cells false
return false;
}
};
JTable authorsTable = new JTable(authorstableModel);
authorsTable.getColumnModel().getColumn(0).setPreferredWidth(500);
authorsTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
try {
authorsTable.setAutoCreateRowSorter(true);
} catch(Exception continuewithNoSort) {
}
JScrollPane tableScroll = new JScrollPane(authorsTable);
Dimension tablePreferred = tableScroll.getPreferredSize();
tableScroll.setPreferredSize(new Dimension(500, tablePreferred.height/3));
authorsPanel.add(tableScroll);
Here is a screenshot:
When I get rid of the line:
authorsTable.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
Then the table returns to being the full width of the panel, so it seems like I need this line.

The java docs on BorderLayout states :
The components are laid out according to their preferred sizes and the
constraints of the container's size. The NORTH and SOUTH components
may be stretched horizontally; the EAST and WEST components may be
stretched vertically; the CENTER component may stretch both
horizontally and vertically to fill any space left over.
You have used authorsPanel.add(tableScroll) to add the JScrollPane to the JPanel. So you are basically adding it to the center. So this is going to occupy the whole space that is lying vacant.
The solution to your problem lies in choosing a different layout. I could suggest MigLayout which is very versatile and you can get all kinds of effects using it.

You add your scroll pane to a panel with BorderLayout. BorderLayout does not care about preferred size. Use e.g GridBagLayout with proper constraints or you can BoxLayout (with horizontal flow) placing the table first and an empty panel second as place holder.

Adding JScrollPane to JTable doesn't show up

I'm pretty new to Javas swings, so sorry if this is something trivial. This is the constructor, I excluded unnecessary form items. (I tried running the code as short as this, but the problem still appears)
//This just opens a connection to MySQL server, this doesn't create any problems.
bp = BazaPodataka.getBaza();
//Forming the main frame..
JFrame frame = new JFrame();
{
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
frame.setBounds(d.width/2 - sirina/2, d.height/2 - visina/2, sirina, visina);
}
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setLayout(new BorderLayout(0, 0));
//Adding a layered pane so I can place items inside the form more 'freely'
JLayeredPane layeredPane = new JLayeredPane();
frame.getContentPane().add(layeredPane, BorderLayout.CENTER);
//Adding a table
JTable table = new JTable();
String[] rowData = {"Name:", "Price:", "Cathegory:", "Sum:"};
DefaultTableModel model = new DefaultTableModel(rowData, 0);
JScrollPane skrol = new JScrollPane(table);
table.setModel(model);
//The 2 lines below work as intended
ResultSet rs = (ResultSet) bp.query("SELECT * FROM table"); //This calls a query
popuniTabelu(rs, model); //This populates the table.
table.setBounds(10, 110, 500, 350);
table.setEnabled(false);
table.setShowHorizontalLines(false);
layeredPane.add(table);
Populating the table and displaying it isn't the problem, there's enough information inside the table 'table' that the user even needs to scroll down.
But that's where the problem begins, the scroll doesn't show up. How do I implement it from here. I tried following solutions I found on google, but they pretty much sum up on:
JScrollPane scroll = new JScrollPane(table);
Which simply doesn't work in my case.
The problem may be trivial, if it is, I'm sorry, I'm still learning swing. Also, sorry for my bad english, it's not my native language. :)
Also, if there's something I forgot to include, please let me know.
Thank you!

You add your table to 2 components :
JScrollPane skrol = new JScrollPane(table);
and
layeredPane.add(table);
Because of Swing component can have just one parent component second statment override first, so your JScrollPane is empty. Seems you need to remove layeredPane.add(table);
As mentioned here
Each GUI component can be contained only once. If a component is already in a container and you try to add it to another container, the component will be removed from the first container and then added to the second.

JTable in JScrollPane forces scrolling when not required

I have a JTable in a JScrollPane. If the screen shows half of a row in the JTable, when clicking on the JTable, the JScrollPane scrolls automatically to show the entire row.
How do I stop that behavior, such that a click will not scroll the JScrollPane.
Thanks!

The behavior is enforced by calling scrollRectToVisible() from the table's UI delegate, typically derived from BasicTableUI. Short of supplying your own delegate, you can use setPreferredScrollableViewportSize() to make the height of enclosing Container an intergral multiple of the rowHeight, as shown below and in this example.
private static final int N_ROWS = 8;
private JTable table = new JTable();
...
Dimension d = new Dimension(
table.getPreferredScrollableViewportSize().width,
N_ROWS * table.getRowHeight());
table.setPreferredScrollableViewportSize(d);
add(new JScrollPane(table));

Scrolling issue (Java-JFrame-JScrollBar)

INTRO:
I created a java application using JFrame. I have a JMenuBar at the top and under that I'd like to display rows of text.
PURPOSE:
When I have 50 rows and only 20 are displayable at once, I'd like to be able to scroll down and back up again.
PROBLEM:
Of course, my theory doesn't wanna work as it should. My problem is that I don't know how to add a vertical scroll properly.
QUESTION:
How should I change this code to reach my goal?
public void display(){
Container content = this.window.getContentPane();
content.setLayout(new BorderLayout());
Border border = LineBorder.createGrayLineBorder();
//this is just a sample
for(int i = 0;i<50;i++){
JLabel lab = new JLabel("lonyaladek");
lab.setSize(570, 20);
lab.setBorder(border);
lab.setLocation(10, 20+(i*25));
content.add(lab);
}
//scroll
JScrollBar sb = new JScrollBar(JScrollBar.VERTICAL, 0, 0, 0, 0);
content.add(sb);
}

First you need to start with a layout manager that allows you to add multiple components to the container. Maybe a GridLayout is the best place to start.
Then you add this container to the scrollPane and then you add the scrollpane to the window.
So the basic code would be:
JPanel panel = new JPanel( new GridLayout(0, 1) );
panel.add(...);
panel.add(...);
JScrollPane scrollPane = new JScrollPane( panel );
window.add(scrollPane, BorderLayout.CENTER);
I suggest you read the section from the Swing tutorial on How to Use Scroll Panes for more info.