Displaying custom drawn panels in a panel with FlowLayout vs GridLayout

Question

I am having trouble to display my custom panels(on which I have drawn) in another panel with FlowLayout. When I use this layout only a small part of their top-left corner appears, when using the GridLayout they are displayed as should, all. Why is this? Is there any way around it?
The following is the code:
package diagramillustrator;
import java.awt.*;
import java.util.Vector;
import javax.swing.*;
public class ClassDiagram extends JPanel
    //fields
    //<editor-fold>
    //general info
    public String title = "class";
    public String name;
    public Vector interfaces;
    public Vector exceptions;
    public String superclass;
    public Vector subClasses;
    public boolean superClass;
    public boolean subClass;
    public String dPackage;
    public String dExtends;
    //variables
    public FieldStructure field;
    //methods
    public MethodStructure constructor;
    public MethodStructure metho;
    //</editor-fold>
    /** Creates a new instance of ClassDiagram */
    public ClassDiagram()
        super();
        super.setSize(132,75);
    protected void paintComponent(Graphics g)
       setBackground(Color.WHITE);
       Graphics2D g2d = (Graphics2D) g;
       super.paintComponent(g2d);
       g2d.setStroke(new BasicStroke(2f));
       g2d.drawRect(1,1,132,25);
       g2d.setFont(new Font("arial", Font.BOLD, 12));
       g2d.drawString(title, 4,18);
       g2d.setColor(Color.LIGHT_GRAY);
       g2d.fillRect(1,25,132,25);
       g2d.setColor(Color.BLACK);
       g2d.drawRect(1,25,132,25);
       g2d.setColor(Color.WHITE);
       g2d.fillRect(1,51,132,25);
       g2d.setColor(Color.BLACK);
       g2d.drawRect(1,50,132,25);
    public static void main(String[] args)
        JFrame f = new JFrame("Testing ClassDiagram");
        f.setSize(500,400);
        //layout shows it correctly
        JPanel panel1 = new JPanel(new GridLayout());
        //layout shows it incorrectly
        //JPanel panel1 = new JPanel(new FlowLayout());
        panel1.setSize(200,200);
        ClassDiagram c1 = new ClassDiagram();
        ClassDiagram c2 = new ClassDiagram();
        ClassDiagram c3 = new ClassDiagram();
        panel1.add(c1);
        panel1.add(c2);
        panel1.add(c3);
        f.add(panel1);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.show();
}Here is the main method included in the class(the main method is used for testing here) where the adding etc is done.
public static void main(String[] args)
        JFrame f = new JFrame("Testing ClassDiagram");
        f.setSize(500,400);
        //layout shows it correctly
        JPanel panel1 = new JPanel(new GridLayout());
        //layout shows it incorrectly
        //JPanel panel1 = new JPanel(new FlowLayout());
        panel1.setSize(200,200);
        ClassDiagram c1 = new ClassDiagram();
        ClassDiagram c2 = new ClassDiagram();
        ClassDiagram c3 = new ClassDiagram();
        panel1.add(c1);
        panel1.add(c2);
        panel1.add(c3);
        f.add(panel1);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.show();
    }Please help.
Thanks,
AndXer

Answer 1

Layout managers.
JPanel panel1 = new JPanel(new GridLayout());GridLayout divides the availabale space into equal cells and expands each child component to fill the cell.
JPanel panel1 = new JPanel(new FlowLayout());FlowLayout attempts to show each child component at its preferred size. The preferredSize is determined by the layout manager in the process of laying out the children. For a graphic component, ie, a component with no child components, the request for the components preferredSize will return the default size which is 10,10 for JPanel. Therefore you will need to either set the preferredSize for the gtaphic component or override the getPreferredSize method and return the desired Dimension. Another limitation of FlowLayout is that it attempts to lay its children out in&#8211;line.
GridBagLayout also respects the preferredSize of child components and offers more versatility.
import java.awt.*;
import javax.swing.*;
public class CD extends JPanel
    public String title = "class";
    public CD()
        super();
        setPreferredSize(new Dimension(132,75));
        setBackground(Color.WHITE);
    protected void paintComponent(Graphics g)
        Graphics2D g2d = (Graphics2D) g;
        super.paintComponent(g2d);
        g2d.setStroke(new BasicStroke(2f));
        g2d.drawRect(1,1,130,25);
        g2d.setFont(new Font("arial", Font.BOLD, 12));
        g2d.drawString(title, 4,18);
        g2d.setColor(Color.LIGHT_GRAY);
        g2d.fillRect(1,25,130,25);
        g2d.setColor(Color.BLACK);
        g2d.drawRect(1,25,130,25);
        g2d.setColor(Color.WHITE);
        g2d.fillRect(1,51,130,25);
        g2d.setColor(Color.BLACK);
        g2d.drawRect(1,50,130,25);
    public static void main(String[] args)
        JPanel panel1 = new JPanel(new GridBagLayout());
        // This has little affect until after realization and
        // is then subject to its parent layout manager. Use
        // the preferredSize for better results.
        //panel1.setSize(200,200);
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(5,5,5,5);
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;
        // Add some components
        int n = 5;
        // and specify columns
        int cols = 3;
        for(int j = 0; j < n; j++) {
            gbc.gridwidth = ((j+1) % cols == 0) ? GridBagConstraints.REMAINDER
                                                : 1;
            panel1.add(new CD(), gbc);
        JFrame f = new JFrame("Testing ClassDiagram");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(panel1);
        f.setSize(500,400);
        f.setLocation(200,200);
        f.setVisible(true);
}