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Class java.awt.GridBagLayout

java.lang.Object
   |
   +----java.awt.GridBagLayout

public class GridBagLayout

extends Object

implements LayoutManager2, Serializable

To use a GridBagLayout effectively, you must customize one or more of its components' GridBagConstraints. You customize a GridBagConstraints object by setting one or more of its instance variables:

gridx, gridy

Specifies the cell at the upper left of the component's display area, where the upper-left-most cell has address gridx=0, gridy=0. Use GridBagConstraints.RELATIVE (the default value) to specify that the component be just placed just to the right of (for gridx) or just below (for gridy) the component that was added to the container just before this component was added.

gridwidth, gridheight

Specifies the number of cells in a row (for gridwidth) or column (for gridheight) in the component's display area. The default value is 1. Use GridBagConstraints.REMAINDER to specify that the component be the last one in its row (for gridwidth) or column (for gridheight). Use GridBagConstraints.RELATIVE to specify that the component be the next to last one in its row (for gridwidth) or column (for gridheight).

fill

Used when the component's display area is larger than the component's requested size to determine whether (and how) to resize the component. Valid values are GridBagConstraints.NONE (the default), GridBagConstraints.HORIZONTAL (make the component wide enough to fill its display area horizontally, but don't change its height), GridBagConstraints.VERTICAL (make the component tall enough to fill its display area vertically, but don't change its width), and GridBagConstraints.BOTH (make the component fill its display area entirely).

ipadx, ipady

Specifies the internal padding: how much to add to the minimum size of the component. The width of the component will be at least its minimum width plus ipadx*2 pixels (since the padding applies to both sides of the component). Similarly, the height of the component will be at least the minimum height plus ipady*2 pixels.

insets

Specifies the external padding of the component -- the minimum amount of space between the component and the edges of its display area.

anchor

Used when the component is smaller than its display area to determine where (within the area) to place the component. Valid values are GridBagConstraints.CENTER (the default), GridBagConstraints.NORTH, GridBagConstraints.NORTHEAST, GridBagConstraints.EAST, GridBagConstraints.SOUTHEAST, GridBagConstraints.SOUTH, GridBagConstraints.SOUTHWEST, GridBagConstraints.WEST, and GridBagConstraints.NORTHWEST.

weightx, weighty

Used to determine how to distribute space; this is important for specifying resizing behavior. Unless you specify a weight for at least one component in a row (weightx) and column (weighty), all the components clump together in the center of their container. This is because when the weight is zero (the default), the GridBagLayout puts any extra space between its grid of cells and the edges of the container.

• 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);
c.gridwidth = GridBagConstraints.REMAINDER; //end row
makebutton("Button4", gridbag, c);
c.weightx = 0.0;		   //reset to the default
makebutton("Button5", gridbag, c); //another row
c.gridwidth = GridBagConstraints.RELATIVE; //next-to-last in row
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
c.gridwidth = GridBagConstraints.REMAINDER; //end row
c.gridheight = 1;		   //reset to the default
makebutton("Button9", gridbag, c);
makebutton("Button10", gridbag, c);
setSize(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.setSize(f.getPreferredSize());
f.show();
}
}

columnWeights

columnWidths

comptable

defaultConstraints

layoutInfo

MAXGRIDSIZE

MINSIZE

PREFERREDSIZE

rowHeights

rowWeights

GridBagLayout()

Creates a gridbag layout.

addLayoutComponent(Component, Object)

Adds the specified component to the layout, using the specified constraint object.

addLayoutComponent(String, Component)

Adds the specified component with the specified name to the layout.

AdjustForGravity(GridBagConstraints, Rectangle)

ArrangeGrid(Container)

getConstraints(Component)

Retrieves the constraints for the specified component.

getLayoutAlignmentX(Container)

Returns the alignment along the x axis.

getLayoutAlignmentY(Container)

Returns the alignment along the y axis.

getLayoutDimensions()

GetLayoutInfo(Container, int)

Print the layout constraints.

getLayoutOrigin()

getLayoutWeights()

GetMinSize(Container, GridBagLayoutInfo)

invalidateLayout(Container)

Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.

layoutContainer(Container)

Lays out the container in the specified panel.

location(int, int)

lookupConstraints(Component)

Retrieves the constraints for the specified component.

maximumLayoutSize(Container)

Returns the maximum dimensions for this layout given the components in the specified target container.

minimumLayoutSize(Container)

Returns the minimum dimensions needed to layout the components contained in the specified panel.

preferredLayoutSize(Container)

Returns the preferred dimensions for this layout given the components in the specified panel.

removeLayoutComponent(Component)

Removes the specified component from the layout.

setConstraints(Component, GridBagConstraints)

Sets the constraints for the specified component.

toString()

Returns the String representation of this GridLayout's values.

 protected static final int MAXGRIDSIZE

 protected static final int MINSIZE

 protected static final int PREFERREDSIZE

 protected Hashtable comptable

 protected GridBagConstraints defaultConstraints

 protected GridBagLayoutInfo layoutInfo

 public int columnWidths[]

 public int rowHeights[]

 public double columnWeights[]

 public double rowWeights[]

 public GridBagLayout()

Creates a gridbag layout.

 public void setConstraints(Component comp,
                            GridBagConstraints constraints)

Sets the constraints for the specified component.

Parameters:

comp - the component to be modified

constraints - the constraints to be applied

 public GridBagConstraints getConstraints(Component comp)

Retrieves the constraints for the specified component. A copy of the constraints is returned.

Parameters:

comp - the component to be queried

 protected GridBagConstraints lookupConstraints(Component comp)

Retrieves the constraints for the specified component. The return value is not a copy, but is the actual constraints class used by the layout mechanism.

Parameters:

comp - the component to be queried

 public Point getLayoutOrigin()

 public int[][] getLayoutDimensions()

 public double[][] getLayoutWeights()

 public Point location(int x,
                       int y)

 public void addLayoutComponent(String name,
                                Component comp)

Adds the specified component with the specified name to the layout.

Parameters:

name - the name of the component

comp - the component to be added

 public void addLayoutComponent(Component comp,
                                Object constraints)

Adds the specified component to the layout, using the specified constraint object.

Parameters:

comp - the component to be added

constraints - where/how the component is added to the layout.

 public void removeLayoutComponent(Component comp)

Removes the specified component from the layout. Does not apply.

Parameters:

comp - the component to be removed

 public Dimension preferredLayoutSize(Container parent)

Returns the preferred dimensions for this layout given the components in the specified panel.

Parameters:

parent - the component which needs to be laid out

See Also:

minimumLayoutSize

 public Dimension minimumLayoutSize(Container parent)

Returns the minimum dimensions needed to layout the components contained in the specified panel.

Parameters:

parent - the component which needs to be laid out

See Also:

preferredLayoutSize

 public Dimension maximumLayoutSize(Container target)

Returns the maximum dimensions for this layout given the components in the specified target container.

Parameters:

target - the component which needs to be laid out

See Also:

Container, minimumLayoutSize, preferredLayoutSize

 public float getLayoutAlignmentX(Container parent)

Returns the alignment along the x axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.

 public float getLayoutAlignmentY(Container parent)

Returns the alignment along the y axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.

 public void invalidateLayout(Container target)

Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.

 public void layoutContainer(Container parent)

Lays out the container in the specified panel.

Parameters:

parent - the specified component being laid out

See Also:

Container

 public String toString()

Returns the String representation of this GridLayout's values.

Overrides:

toString in class Object

 protected GridBagLayoutInfo GetLayoutInfo(Container parent,
                                           int sizeflag)

Print the layout constraints. Useful for debugging.

 protected void AdjustForGravity(GridBagConstraints constraints,
                                 Rectangle r)

 protected Dimension GetMinSize(Container parent,
                                GridBagLayoutInfo info)

 protected void ArrangeGrid(Container parent)

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