CODEWITHSUNDEEP
javaswingjlabelgrid-layout
Sam
Sam

Reputation: 3167

JLabels to be resized in a GridLayout

I have a very simple Java program (see below). The GridLayout has 20 rows and 4 columns. As you know the elements are supposed to be added horizontally by (GridLayout) definition. However, I get the two elements (labels) placed one above the other, vertically.

I colored them and realised the labels take up the whole row, hence the vertical effect. But then I also used setSize(5,5) with each to make them smaller, however they still take up the whole row. Any advice as to why this happens and how to fix/set smaller size/etc?

public class Sam extends JFrame {

    public JButton btn_arr;
    public Container c;
    public JLabel[] lbl = new JLabel[20];


    public Sam()
    {
        c = getContentPane();
        c.setLayout(new GridLayout(20,4));
        lbl[1] = new JLabel("Column1");
        c.add(lbl[1]);

        lbl[2] = new JLabel("Column2");
        c.add(lbl[2]);

        show();     
    }

    public static void main(String[] args) 
    {
        Sam x = new Sam();
        x.setVisible(true);
        x.setSize(7500,4500);
    }

}

Upvotes: 2

Views: 3960

Answers (2)

Jere
Jere

Reputation: 601

One thing to keep in mind with the GridLayout is it that it is designed to cover the entire containing panel sizing the cells as equally as possible, and elements added to the cells will be expanded to fill the entire cell. So as the cell sizes change, the labels will also change in size. Effectively grid cells force an expansion/contraction in both X and Y direction of all contained elements.

One way to prevent that from happening if you must use the GridLayout is to not add the labels directly to the container that uses the GridLayout, but instead put each label inside a JPanel that uses a FlowLayout (the default) that you can set alignment of either Left, Middle or Right, then add that JPanel to the Grid container. The JPanel will be resized but it will not change the size of the Label.

Or use the GridBagLayout manager. More complex, but once you understand it, it makes life easier. But as Hovercraft mentioned, if what you are trying to do is create a grid with column headers, a JTable might be a better option.

Upvotes: 2

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285403

You're only adding two components to the grid so they will fill it up. You need to add more components to the grid as placeholders so that it can place the original JLabels in their proper place, perhaps empty JLabels or JPanels.

As an aside, you should avoid setting the size of any Swing component. Your current size of 7500, 4500 is a bit on the large size.

As a second aside, perhaps you want to use a JTable instead here.

Edit: if you want a GridLayout with 4 columns and variable number of rows, use 0 for your GridLayout row constant:

c.setLayout(new GridLayout(0, 4));

e.g.,

import java.awt.*;
import javax.swing.*;

public class Sam extends JFrame {
   public static final int COLUMN_COUNT = 4;

   public JButton btn_arr;
   public Container c;
   public JLabel[] lbl = new JLabel[COLUMN_COUNT];

   public Sam() {
      c = getContentPane();
      c.setLayout(new GridLayout(0, COLUMN_COUNT));

      for (int i = 0; i < lbl.length; i++) {
         lbl[i] = new JLabel("Column " + (i + 1));
         c.add(lbl[i]);
      }

   }

   public static void main(String[] args) {
      Sam x = new Sam();
      x.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      x.pack();
      x.setLocationRelativeTo(null);
      x.setVisible(true);
      // x.setSize(7500,4500);
   }

}

But still I wonder if a JTable wouldn't work better here.

Upvotes: 3

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