GridLayout not working?

[James Brooks]

Ladies/gents,

I'm having a problem with the GridLayout. I've set it to (2, 3), and from what I understand, components are added from top to bottom, left to right. Why, then, is my np (NumberPanel) being pushed down to the next row, instead of populating in column number 3 on the top row? Any ideas? Also, setSize() does nothing to modify the size of this JFrame???

Thanks in advance!
Main class;

   
import javax.swing.*;
import java.awt.*;
/**
 The Main class creates a frame and draws shapes recursively on it.
 */
public class Main extends JFrame{
   JLabel jl;
    public Main(){
       ColorPanel cp = new ColorPanel();
       ShapePanel sp = new ShapePanel();
       NumberPanel np = new NumberPanel();
      // this.setSize(400, 600);
       this.setLayout(new GridLayout(2, 3));
       this.add(sp);
       this.add(cp);
       this.add(np);
       this.pack();
       this.setVisible(true);

    }
    /**
     The main thread in the program.
     @param args The command line arguments to be parsed.
     */
    public static void main(String[] args) {
       Main m = new Main();
    }

}

 

ColorPanel class:

  import javax.swing.*;
import java.awt.*;
public class ColorPanel extends JPanel{
    
    JRadioButton jrb1;
    JRadioButton jrb2;
    JRadioButton jrb3;
    JRadioButton jrb4;
    ButtonGroup bg1;
    
    public ColorPanel(){
        
        jrb1 = new JRadioButton("Black");
        jrb2 = new JRadioButton("Red");
        jrb3 = new JRadioButton("Blue");
        jrb4 = new JRadioButton("Green");
        bg1 = new ButtonGroup();
        bg1.add(jrb1);
        bg1.add(jrb2);
        bg1.add(jrb3);
        bg1.add(jrb4);
        this.setLayout(new GridLayout(4, 1));
        this.add(jrb1);
        this.add(jrb2);
        this.add(jrb3);
        this.add(jrb4);
    }

}
  

NumberPanel class:

  import javax.swing.*;
import java.awt.*;
public class NumberPanel extends JPanel{
    JLabel jl;
    JTextField jtf;
    public NumberPanel(){
        jl = new JLabel("Enter the number of shapes to draw:");
        jtf = new JTextField(5);
        this.setLayout(new GridLayout(2, 1));
        this.add(jl);
        this.add(jtf);
    }
}
  

ShapePanel class:

  
import javax.swing.*;
import java.awt.*;
public class ShapePanel extends JPanel{
    JRadioButton jrb1;
    JRadioButton jrb2;
    ButtonGroup bg;

    public ShapePanel(){
        jrb1 = new JRadioButton("Square");
        jrb2 = new JRadioButton("Circle");
        bg = new ButtonGroup();
        bg.add(jrb1);
        bg.add(jrb2);
        this.setLayout(new GridLayout(2, 1));
        this.add(jrb1);
        this.add(jrb2);
    }
}
  

[Harold Lime]

http://java.sun.com/j2se/1.4.2/docs/api/java/awt/GridLayout.html

Says they are added left to right, then top to bottom.

[James Brooks]

Harold Lime wrote:http://java.sun.com/j2se/1.4.2/docs/api/java/awt/GridLayout.html

Says they are added left to right, then top to bottom.

Yeah, so, I should have my top row of 3 columns populated first, right? Then my second row?

[Rob Spoor]

If the number of rows is larger than 0, the number of columns specified is ignored and instead there will be "(ncomponents + nrows - 1) / nrows" columns, where ncomponents is the number of components and nrows is the number of rows. In your code, ncomponents is 3 and nrows is 2, so the number of columns will be 2.

This is also mentioned in the API:

When both the number of rows and the number of columns have been set to non-zero values, either by a constructor or by the setRows and setColumns methods, the number of columns specified is ignored. Instead, the number of columns is determined from the specified number of rows and the total number of components in the layout.

So if you want to use a fixed number of columns, just set the number of rows to 0. It will then respect the column count and just keep filling until all components are put in place.

[James Brooks]

Rob Prime wrote:If the number of rows is larger than 0, the number of columns specified is ignored and instead there will be "(ncomponents + nrows - 1) / nrows" columns, where ncomponents is the number of components and nrows is the number of rows. In your code, ncomponents is 3 and nrows is 2, so the number of columns will be 2.

This is also mentioned in the API:

When both the number of rows and the number of columns have been set to non-zero values, either by a constructor or by the setRows and setColumns methods, the number of columns specified is ignored. Instead, the number of columns is determined from the specified number of rows and the total number of components in the layout.

So if you want to use a fixed number of columns, just set the number of rows to 0. It will then respect the column count and just keep filling until all components are put in place.

Ah, hah! Thanks, Rob!