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public  class  java.awt.GridBagLayout
    extends  java.lang.Object  (I-§1.12)
    implements java.awt.LayoutManager  (II-§1.43)
{
        // Fields
    protected final static int MAXGRIDSIZE;	§1.22.1
    protected final static int MINSIZE;	§1.22.2

        // Constructors
    public GridBagLayout();	§1.22.3

        // Methods
    public void addLayoutComponent(String  name, 	§1.22.4
                                          Component  comp);
    public GridBagConstraints getConstraints(Component  comp);	§1.22.5
    public void layoutContainer(Container  target);	§1.22.6
    protected GridBagConstraints	§1.22.7
        lookupConstraints(Component  comp);
    public Dimension minimumLayoutSize(Container  target);	§1.22.8
    public Dimension preferredLayoutSize(Container  target);	§1.22.9
    public void removeLayoutComponent(Component  comp);	§1.22.10
    public void	§1.22.11
        setConstraints(Component  comp, GridBagConstraints  constraints);
    public String toString();	§1.22.12
}

Each grid bag layout manager uses a rectangular grid of cells, with each component occupying one or more cells (called its display area). Each component in a grid bag layout is associated with a set of constraints contained within a GridBag-Constraints instance that specifies how the component is to be laid out within its display area.

The manner in which the grid bag layout manager places a set of components depends on each component's constraints and its minimum size, as well as the preferred size of the components' container.

To use a grid bag layout effectively, one or more components must have a customized GridBagConstraints objects created for it.

The fields of the GridBagConstraints object are described more fully in §1.21.

The following figure shows ten components (all buttons) managed by a grid bag layout manager:

Each of the ten components has the fill field of their constraint set to GridBagConstraints.BOTH. In addition, the buttons have the following non-default constraints:

In addition, the components have the following non-default constraints:

• Button1, Button2, Button3: weightx=1.0
• Button4: weightx=1.0, gridwidth=GridBagConstraints.REMAINDER
• Button5: gridwidth=GridBagConstraints.REMAINDER
• Button6: gridwidth=GridBagConstraints.RELATIVE
• Button7: gridwidth=GridBagConstraints.REMAINDER
• Button8: gridheight=2, weighty=1.0,
• Button9, Button 10: gridwidth=GridBagConstraints.REMAINDER

import  java.awt.*;
import  java.util.*;
import  java.applet.Applet;
public  class  GridBagEx1  extends  Applet  {
       protected  void  makebutton(String  name,  
                              GridBagLayout  gridbag,
                                GridBagConstraints  c)  {
                Button  button  =  new  Button(name);
                gridbag.setConstraints(button,  c);
               add(button);
        }

        public  void  init()  {
                GridBagLayout  gridbag  =  new  GridBagLayout();
                GridBagConstraints  c  =  new  GridBagConstraints();
                setFont(new  Font("Helvetica",  Font.PLAIN,  14));
                setLayout(gridbag);
                c.fill  =  GridBagConstraints.BOTH;
                c.weightx  =  1.0;
                makebutton("Button1",  gridbag,  c);
                makebutton("Button2",  gridbag,  c);
                makebutton("Button3",  gridbag,  c);

        // end row	
        c.gridwidth  =  GridBagConstraints.REMAINDER;  
            makebutton("Button4",  gridbag,  c);
                c.weightx  =  0.0;		      //reset  to  the  default
                makebutton("Button5",  gridbag,  c);  //another  row

            // next-to last  in  row
            c.gridwidth  =  GridBagConstraints.RELATIVE;  
                makebutton("Button6",  gridbag,  c);
            c.gridwidth  =  GridBagConstraints.REMAINDER;  //end  row
                makebutton("Button7",  gridbag,  c);
            c.gridwidth  =  1;	      	      // reset to the default
            c.gridheight  =  2;
                c.weighty  =  1.0;
                makebutton("Button8",  gridbag,  c);
                c.weighty  =  0.0;		      //reset  to  the  default

            // end  row
            c.gridwidth  =  GridBagConstraints.REMAINDER;  
            c.gridheight  =  1;		      // reset to the default
                makebutton("Button9",  gridbag,  c);
                makebutton("Button10",  gridbag,  c);
                resize(300,  100);
        }	

        public  static  void  main(String  args[])  {
            Frame  f  =  new  Frame("GridBag  Layout  Example");
               GridBagEx1  ex1  =  new  GridBagEx1();
            ex1.init();
            f.add("Center",  ex1);
            f.pack();
        f.show();
        }
}

The maximum number of grid positions (both horizontally and vertically) that can be laid out by the grid bag layout.

The smallest grid that can be laid out by the grid bag layout.

Creates a grid bag layout manager

This method is not used by the grid bag layout manager.

Parameters:

name - a tag understood by the layout manager

comp - the component to be added

Parameters:

comp - the component to be queried

Returns:

the constraint for the specified component in this grid bag layout. A copy of the constraint object is returned.

Lays out the container argument using this grid bag layout.

This method reshapes the components in the specified container in order to satisfy the constraints of this GridBagLayout object.

Most applications do not call this method directly. This method is called when a container calls its layout method (II-§1.11.11).

Parameters:

target - the container in which to do the layout.

See Also:

Container (II-§1.11).

Retrieves the constraints for the specified component in this grid bag layout. The return value is not a copy, but is the actual GridBagConstraints object used by the layout mechanism.

Parameters:

comp - the component to be queried

Returns:

the contraints for the specified component.

Determines the minimum size of the target container using this grid bag layout.

This method is called when a container calls its layout method (II-§1.11.11). Most applications do not call this method directly.

Parameters:

target - the container in which to do the layout

Returns:

the minimum dimensions needed to lay out the subcomponents of the specified container.

See Also:

preferredLayoutSize (II-§1.22.9).

Determines the preferred size of the target container using this grid bag layout.

Most applications do not call this method directly. This method is called when a container calls its preferredSize method (II-§1.11.17).

Parameters:

target - the container in which to do the layout

Returns:

the preferred dimensions to lay out the subcomponents of the specified container.

See Also:

minimumLayoutSize (II-§1.22.8).

Removes the specified component from this layout.

Most applications do not call this method directly. This method is called when a container calls its remove (II-§1.11.19) or removeAll (II-§1.11.20) methods.

Parameters:

comp - the component to be removed

Sets the constraints for the specified component in this layout

Parameters:

comp - the component to be modified

constraints - the constraints to be applied

Returns:

a string representation of this grid bag layout.

Overrides:

toString in class Object (I-§1.12.9).

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