java.awt
Class FlowLayout

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

public class FlowLayout

extends Object

implements LayoutManager, Serializable

A flow layout arranges components in a left-to-right flow, much like lines of text in a paragraph. Flow layouts are typically used to arrange buttons in a panel. It will arrange buttons left to right until no more buttons fit on the same line. Each line is centered.

For example, the following picture shows an applet using the flow layout manager (its default layout manager) to position three buttons:

Here is the code for this applet:

 import java.awt.*;
 import java.applet.Applet;

 public class myButtons extends Applet {
     Button button1, button2, button3;
     public void init() {
         button1 = new Button("Ok");
         button2 = new Button("Open");
         button3 = new Button("Close");
         add(button1);
         add(button2);
         add(button3);
     }
 }
 

A flow layout lets each component assume its natural (preferred) size.

Since:

JDK1.0

See Also:

Serialized Form

Field Summary

static int	CENTER This value indicates that each row of components should be centered.
static int	LEADING This value indicates that each row of components should be justified to the leading edge of the container's orientation, e.g.
static int	LEFT This value indicates that each row of components should be left-justified.
static int	RIGHT This value indicates that each row of components should be right-justified.
static int	TRAILING This value indicates that each row of components should be justified to the leading edge of the container's orientation, e.g.

Constructor Summary

FlowLayout()
Constructs a new Flow Layout with a centered alignment and a default 5-unit horizontal and vertical gap.

FlowLayout(int align)
Constructs a new Flow Layout with the specified alignment and a default 5-unit horizontal and vertical gap.

FlowLayout(int align, int hgap, int vgap)
Creates a new flow layout manager with the indicated alignment and the indicated horizontal and vertical gaps.

Method Summary

void	addLayoutComponent(String name, Component comp) Adds the specified component to the layout.
int	getAlignment() Gets the alignment for this layout.
int	getHgap() Gets the horizontal gap between components.
int	getVgap() Gets the vertical gap between components.
void	layoutContainer(Container target) Lays out the container.
Dimension	minimumLayoutSize(Container target) Returns the minimum dimensions needed to layout the components contained in the specified target container.
Dimension	preferredLayoutSize(Container target) Returns the preferred dimensions for this layout given the components in the specified target container.
void	removeLayoutComponent(Component comp) Removes the specified component from the layout.
void	setAlignment(int align) Sets the alignment for this layout.
void	setHgap(int hgap) Sets the horizontal gap between components.
void	setVgap(int vgap) Sets the vertical gap between components.
String	toString() Returns a string representation of this FlowLayout object and its values.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

LEFT

public static final int LEFT

This value indicates that each row of components should be left-justified.

CENTER

public static final int CENTER

This value indicates that each row of components should be centered.

RIGHT

public static final int RIGHT

This value indicates that each row of components should be right-justified.

LEADING

public static final int LEADING

This value indicates that each row of components should be justified to the leading edge of the container's orientation, e.g. to the left in left-to-right orientations.

See Also:

Component.getComponentOrientation(), ComponentOrientation

Since:

JDK1.2 Package-private pending API change approval

TRAILING

public static final int TRAILING

This value indicates that each row of components should be justified to the leading edge of the container's orientation, e.g. to the right in left-to-right orientations.

See Also:

Component.getComponentOrientation(), ComponentOrientation

Since:

JDK1.2 Package-private pending API change approval

Constructor Detail

FlowLayout

public FlowLayout()

Constructs a new Flow Layout with a centered alignment and a default 5-unit horizontal and vertical gap.

FlowLayout

public FlowLayout(int align)

Constructs a new Flow Layout with the specified alignment and a default 5-unit horizontal and vertical gap. The value of the alignment argument must be one of FlowLayout.LEFT, FlowLayout.RIGHT, or FlowLayout.CENTER.

Parameters:

align - the alignment value

FlowLayout

public FlowLayout(int align,
                  int hgap,
                  int vgap)

Creates a new flow layout manager with the indicated alignment and the indicated horizontal and vertical gaps.

The value of the alignment argument must be one of FlowLayout.LEFT, FlowLayout.RIGHT, or FlowLayout.CENTER.

Parameters:

align - the alignment value.

hgap - the horizontal gap between components.

vgap - the vertical gap between components.

Method Detail

getAlignment

public int getAlignment()

Gets the alignment for this layout. Possible values are FlowLayout.LEFT, FlowLayout.RIGHT, or FlowLayout.CENTER.

Returns:

the alignment value for this layout.

Since:

JDK1.1

See Also:

setAlignment

public void setAlignment(int align)

Sets the alignment for this layout. Possible values are FlowLayout.LEFT, FlowLayout.RIGHT, and FlowLayout.CENTER.

Parameters:

align - the alignment value.

Since:

JDK1.1

See Also:

getAlignment()

getHgap

public int getHgap()

Gets the horizontal gap between components.

Returns:

the horizontal gap between components.

Since:

JDK1.1

See Also:

setHgap(int)

setHgap

public void setHgap(int hgap)

Sets the horizontal gap between components.

Parameters:

hgap - the horizontal gap between components

Since:

JDK1.1

See Also:

getHgap()

getVgap

public int getVgap()

Gets the vertical gap between components.

Returns:

the vertical gap between components.

Since:

JDK1.1

See Also:

setVgap(int)

setVgap

public void setVgap(int vgap)

Sets the vertical gap between components.

Parameters:

vgap - the vertical gap between components

Since:

JDK1.1

See Also:

getVgap()

addLayoutComponent

public void addLayoutComponent(String name,
                               Component comp)

Adds the specified component to the layout. Not used by this class.

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. Not used by this class.

Specified by:

removeLayoutComponent in interface LayoutManager

Parameters:

comp - the component to remove

See Also:

Container.removeAll()

preferredLayoutSize

public Dimension preferredLayoutSize(Container target)

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

Specified by:

preferredLayoutSize in interface LayoutManager

Parameters:

target - the component which needs to be laid out

Returns:

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

See Also:

Container, minimumLayoutSize(java.awt.Container), Container.getPreferredSize()

minimumLayoutSize

public Dimension minimumLayoutSize(Container target)

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

Specified by:

minimumLayoutSize in interface LayoutManager

Parameters:

target - the component which needs to be laid out

Returns:

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

See Also:

preferredLayoutSize(java.awt.Container), Container, Container.doLayout()

layoutContainer

public void layoutContainer(Container target)

Lays out the container. This method lets each component take its preferred size by reshaping the components in the target container in order to satisfy the constraints of this FlowLayout object.

Specified by:

layoutContainer in interface LayoutManager

Parameters:

target - the specified component being laid out.

See Also:

Container, Container.doLayout()

toString

public String toString()

Returns a string representation of this FlowLayout object and its values.

Returns:

a string representation of this layout.

Overrides:

toString in class Object