CODEWITHSUNDEEP
javaswingjtablejscrollpane
Alexander Nenartovich
Alexander Nenartovich

Reputation: 826

Add JButton to JScrollPame

I have the following code taken from GeeksforGeeks that displays the contents of a 2-d array in JTable using JScrollPane:

public class JTableExamples { 
// frame 
JFrame f; 
// Table 
JTable j; 

// Constructor 
JTableExamples() 
{ 
    // Frame initiallization 
    f = new JFrame(); 

    // Frame Title 
    f.setTitle("JTable Example"); 

    // Data to be displayed in the JTable 
    String[][] data = { 
        { "Kundan Kumar Jha", "4031", "CSE" }, 
        { "Anand Jha", "6014", "IT" } 
    }; 

    // Column Names 
    String[] columnNames = { "Name", "Roll Number", "Department" };

    // Initializing the JTable 
    j = new JTable(data, columnNames); 
    j.setBounds(30, 40, 200, 300); 

    // adding it to JScrollPane 
    JScrollPane sp = new JScrollPane(j); 
    f.add(sp); 
    // Frame Size 
    f.setSize(500, 200); 
    // Frame Visible = true 
    f.setVisible(true); 
}

What I am trying to do is add a simple Component (like JButton) underneath the table but it does not seem to work. I tried modifying the code by adding the JButton to JPanel and adding JPanel to the frame:

   JButton button = new JButton("Back");
   JPanel panel = new JPanel();
   panel.add(button);
   f.add(sp);
   f.add(panel);

But this simply deletes the entire table and replaces it with a single button. I also tried adding the button to JPanel and adding that JPanel to JScrollPane:

   JButton button = new JButton("Back");
   JPanel panel = new JPanel();
   panel.add(button);
   sp.add(panel);
   f.add(sp);

But this did not seem to change anything. I also tried to tinker with preferred and maximum size of JScrollPanel to no avail - it always occupies the entire screen and prevents JButton from appearing on the screen.

Not shooting for design here, just functionality: have a JButton appear underneath my JTable. Any suggestions will be greatly appreciated. Thank you in advance!

Upvotes: 0

Views: 70

Answers (1)

camickr
camickr

Reputation: 324098

The default layout manager of a JFrame is the BorderLayout.

f.add(sp);
f.add(panel);

When you don't specify a constraint for the BorderLayout the CENTER is assumed. You can only have a single component added to the CENTER.

Instead your code should be:

f.add(sp, BorderLayout.CENTER);
f.add(panel, BorderLayout.PAGE_END);

Note the default layout manager for a JPanel is the FlowLayout. So the button will be horizontally centered in the panel.

Also, instead of using a JPanel, try adding the button directly to the PAGE_END of the frame to see the difference.

Read the section from the Swing tutorial on Using Layout Manager for more information and examples for using each of the different layout managers to understand the differences of the above suggestions.

Edit:

Is there a way to decrease the height of the table

If you know you have a small table then you can use:

table.setPreferredScrollableViewportSize(table.getPreferredSize());

This will make the scroll pane the size of the table.

Then you use:

//f.setSize(500, 200); 
f.pack();

Now all components will be displayed at their preferred size.

Upvotes: 1

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