Java™ Platform
Standard Ed. 6

java.awt
Class GridLayout

java.lang.Object
  extended by java.awt.GridLayout
All Implemented Interfaces:
LayoutManager, Serializable

public class GridLayout
extends Object
implements LayoutManager, Serializable

The GridLayout class is a layout manager that lays out a container's components in a rectangular grid. The container is divided into equal-sized rectangles, and one component is placed in each rectangle. For example, the following is an applet that lays out six buttons into three rows and two columns:


 import java.awt.*;
 import java.applet.Applet;
 public class ButtonGrid extends Applet {
     public void init() {
         setLayout(new GridLayout(3,2));
         add(new Button("1"));
         add(new Button("2"));
         add(new Button("3"));
         add(new Button("4"));
         add(new Button("5"));
         add(new Button("6"));
     }
 }
 

If the container's ComponentOrientation property is horizontal and left-to-right, the above example produces the output shown in Figure 1. If the container's ComponentOrientation property is horizontal and right-to-left, the example produces the output shown in Figure 2.

Shows 6 buttons in rows of 2. Row 1 shows buttons 1 then 2.
 Row 2 shows buttons 3 then 4. Row 3 shows buttons 5 then 6. Shows 6 buttons in rows of 2. Row 1 shows buttons 2 then 1.
 Row 2 shows buttons 4 then 3. Row 3 shows buttons 6 then 5.
Figure 1: Horizontal, Left-to-Right Figure 2: Horizontal, Right-to-Left

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, for example, if three rows and two columns have been specified and nine components are added to the layout, they will be displayed as three rows of three columns. Specifying the number of columns affects the layout only when the number of rows is set to zero.

Since:
JDK1.0
See Also:
Serialized Form

Constructor Summary
GridLayout()
          Creates a grid layout with a default of one column per component, in a single row.
GridLayout(int rows, int cols)
          Creates a grid layout with the specified number of rows and columns.
GridLayout(int rows, int cols, int hgap, int vgap)
          Creates a grid layout with the specified number of rows and columns.
 
Method Summary
 void addLayoutComponent(String name, Component comp)
          Adds the specified component with the specified name to the layout.
 int getColumns()
          Gets the number of columns in this layout.
 int getHgap()
          Gets the horizontal gap between components.
 int getRows()
          Gets the number of rows in this layout.
 int getVgap()
          Gets the vertical gap between components.
 void layoutContainer(Container parent)
          Lays out the specified container using this layout.
 Dimension minimumLayoutSize(Container parent)
          Determines the minimum size of the container argument using this grid layout.
 Dimension preferredLayoutSize(Container parent)
          Determines the preferred size of the container argument using this grid layout.
 void removeLayoutComponent(Component comp)
          Removes the specified component from the layout.
 void setColumns(int cols)
          Sets the number of columns in this layout to the specified value.
 void setHgap(int hgap)
          Sets the horizontal gap between components to the specified value.
 void setRows(int rows)
          Sets the number of rows in this layout to the specified value.
 void setVgap(int vgap)
          Sets the vertical gap between components to the specified value.
 String toString()
          Returns the string representation of this grid layout's values.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

GridLayout

public GridLayout()
Creates a grid layout with a default of one column per component, in a single row.

Since:
JDK1.1

GridLayout

public GridLayout(int rows,
                  int cols)
Creates a grid layout with the specified number of rows and columns. All components in the layout are given equal size.

One, but not both, of rows and cols can be zero, which means that any number of objects can be placed in a row or in a column.

Parameters:
rows - the rows, with the value zero meaning any number of rows.
cols - the columns, with the value zero meaning any number of columns.

GridLayout

public GridLayout(int rows,
                  int cols,
                  int hgap,
                  int vgap)
Creates a grid layout with the specified number of rows and columns. All components in the layout are given equal size.

In addition, the horizontal and vertical gaps are set to the specified values. Horizontal gaps are placed between each of the columns. Vertical gaps are placed between each of the rows.

One, but not both, of rows and cols can be zero, which means that any number of objects can be placed in a row or in a column.

All GridLayout constructors defer to this one.

Parameters:
rows - the rows, with the value zero meaning any number of rows
cols - the columns, with the value zero meaning any number of columns
hgap - the horizontal gap
vgap - the vertical gap
Throws:
IllegalArgumentException - if the value of both rows and cols is set to zero
Method Detail

getRows

public int getRows()
Gets the number of rows in this layout.

Returns:
the number of rows in this layout
Since:
JDK1.1

setRows

public void setRows(int rows)
Sets the number of rows in this layout to the specified value.

Parameters:
rows - the number of rows in this layout
Throws:
IllegalArgumentException - if the value of both rows and cols is set to zero
Since:
JDK1.1

getColumns

public int getColumns()
Gets the number of columns in this layout.

Returns:
the number of columns in this layout
Since:
JDK1.1

setColumns

public void setColumns(int cols)
Sets the number of columns in this layout to the specified value. Setting the number of columns has no affect on the layout if the number of rows specified by a constructor or by the setRows method is non-zero. In that case, the number of columns displayed in the layout is determined by the total number of components and the number of rows specified.

Parameters:
cols - the number of columns in this layout
Throws:
IllegalArgumentException - if the value of both rows and cols is set to zero
Since:
JDK1.1

getHgap

public int getHgap()
Gets the horizontal gap between components.

Returns:
the horizontal gap between components
Since:
JDK1.1

setHgap

public void setHgap(int hgap)
Sets the horizontal gap between components to the specified value.

Parameters:
hgap - the horizontal gap between components
Since:
JDK1.1

getVgap

public int getVgap()
Gets the vertical gap between components.

Returns:
the vertical gap between components
Since:
JDK1.1

setVgap

public void setVgap(int vgap)
Sets the vertical gap between components to the specified value.

Parameters:
vgap - the vertical gap between components
Since:
JDK1.1

addLayoutComponent

public void addLayoutComponent(String name,
                               Component comp)
Adds the specified component with the specified name to the layout.

Specified by:
addLayoutComponent in interface LayoutManager
Parameters:
name - the name of the component
comp - the component to be added

removeLayoutComponent

public void removeLayoutComponent(Component comp)
Removes the specified component from the layout.

Specified by:
removeLayoutComponent in interface LayoutManager
Parameters:
comp - the component to be removed

preferredLayoutSize

public Dimension preferredLayoutSize(Container parent)
Determines the preferred size of the container argument using this grid layout.

The preferred width of a grid layout is the largest preferred width of all of the components in the container times the number of columns, plus the horizontal padding times the number of columns minus one, plus the left and right insets of the target container.

The preferred height of a grid layout is the largest preferred height of all of the components in the container times the number of rows, plus the vertical padding times the number of rows minus one, plus the top and bottom insets of the target container.

Specified by:
preferredLayoutSize in interface LayoutManager
Parameters:
parent - the container in which to do the layout
Returns:
the preferred dimensions to lay out the subcomponents of the specified container
See Also:
minimumLayoutSize(java.awt.Container), Container.getPreferredSize()

minimumLayoutSize

public Dimension minimumLayoutSize(Container parent)
Determines the minimum size of the container argument using this grid layout.

The minimum width of a grid layout is the largest minimum width of all of the components in the container times the number of columns, plus the horizontal padding times the number of columns minus one, plus the left and right insets of the target container.

The minimum height of a grid layout is the largest minimum height of all of the components in the container times the number of rows, plus the vertical padding times the number of rows minus one, plus the top and bottom insets of the target container.

Specified by:
minimumLayoutSize in interface LayoutManager
Parameters:
parent - 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(java.awt.Container), Container.doLayout()

layoutContainer

public void layoutContainer(Container parent)
Lays out the specified container using this layout.

This method reshapes the components in the specified target container in order to satisfy the constraints of the GridLayout object.

The grid layout manager determines the size of individual components by dividing the free space in the container into equal-sized portions according to the number of rows and columns in the layout. The container's free space equals the container's size minus any insets and any specified horizontal or vertical gap. All components in a grid layout are given the same size.

Specified by:
layoutContainer in interface LayoutManager
Parameters:
parent - the container in which to do the layout
See Also:
Container, Container.doLayout()

toString

public String toString()
Returns the string representation of this grid layout's values.

Overrides:
toString in class Object
Returns:
a string representation of this grid layout

Java™ Platform
Standard Ed. 6

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