java.awt.FlowLayout

All Implemented Interfaces:: LayoutManager, Serializable

public class FlowLayout extends Object implements LayoutManager, Serializable

A flow layout arranges components in a directional flow, much like lines of text in a paragraph. The flow direction is determined by the container's componentOrientation property and may be one of two values:

ComponentOrientation.LEFT_TO_RIGHT
ComponentOrientation.RIGHT_TO_LEFT

Flow layouts are typically used to arrange buttons in a panel. It arranges buttons horizontally until no more buttons fit on the same line. The line alignment is determined by the align property. The possible values are:

LEFT
RIGHT
CENTER
LEADING
TRAILING

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

Graphic of Layout for 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:

1.0

See Also:

Field Summary

Fields

Modifier and Type

Field

Description

static final int

CENTER

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

static final int

LEADING

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

static final int

LEFT

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

static final int

RIGHT

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

static final int

TRAILING

This value indicates that each row of components should be justified to the trailing edge of the container's orientation, for example, to the right in left-to-right orientations.
Constructor Summary

Constructors

Constructor

Description

FlowLayout()

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

FlowLayout(int align)

Constructs a new FlowLayout 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

Modifier and Type

Method

Description

void

addLayoutComponent(String name, Component comp)

Adds the specified component to the layout.

int

getAlignment()

Gets the alignment for this layout.

boolean

getAlignOnBaseline()

Returns true if components are to be vertically aligned along their baseline.

int

getHgap()

Gets the horizontal gap between components and between the components and the borders of the Container

int

getVgap()

Gets the vertical gap between components and between the components and the borders of the Container.

void

layoutContainer(Container target)

Lays out the container.

Dimension

minimumLayoutSize(Container target)

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

Dimension

preferredLayoutSize(Container target)

Returns the preferred dimensions for this layout given the visible 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

setAlignOnBaseline(boolean alignOnBaseline)

Sets whether or not components should be vertically aligned along their baseline.

void

setHgap(int hgap)

Sets the horizontal gap between components and between the components and the borders of the Container.

void

setVgap(int vgap)

Sets the vertical gap between components and between the components and the borders of the Container.

String

toString()

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

Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details
- LEFT
  
  public static final int LEFT
  
  This value indicates that each row of components should be left-justified.
  See Also:
  
  Constant Field Values
- CENTER
  
  public static final int CENTER
  
  This value indicates that each row of components should be centered.
  See Also:
  
  Constant Field Values
- RIGHT
  
  public static final int RIGHT
  
  This value indicates that each row of components should be right-justified.
  See Also:
  
  Constant Field Values
- 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, for example, to the left in left-to-right orientations.
  Since:
  
  1.2
  
  See Also:
  
  Component.getComponentOrientation()
  
  ComponentOrientation
  
  Constant Field Values
- TRAILING
  
  public static final int TRAILING
  
  This value indicates that each row of components should be justified to the trailing edge of the container's orientation, for example, to the right in left-to-right orientations.
  Since:
  
  1.2
  
  See Also:
  
  Component.getComponentOrientation()
  
  ComponentOrientation
  
  Constant Field Values
Constructor Details
- FlowLayout
  
  public FlowLayout()
  
  Constructs a new FlowLayout with a centered alignment and a default 5-unit horizontal and vertical gap.
- FlowLayout
  
  public FlowLayout(int align)
  
  Constructs a new FlowLayout 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, FlowLayout.CENTER, FlowLayout.LEADING, or FlowLayout.TRAILING.
  
  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, FlowLayout.CENTER, FlowLayout.LEADING, or FlowLayout.TRAILING.
  
  Parameters:
  
  align - the alignment value
  
  hgap - the horizontal gap between components and between the components and the borders of the Container
  
  vgap - the vertical gap between components and between the components and the borders of the Container
Method Details
- getAlignment
  
  public int getAlignment()
  
  Gets the alignment for this layout. Possible values are FlowLayout.LEFT, FlowLayout.RIGHT, FlowLayout.CENTER, FlowLayout.LEADING, or FlowLayout.TRAILING.
  Returns:
  
  the alignment value for this layout
  
  Since:
  
  1.1
  
  See Also:
  
  setAlignment(int)
- setAlignment
  
  public void setAlignment(int align)
  Sets the alignment for this layout. Possible values are
  
  FlowLayout.LEFT
  FlowLayout.RIGHT
  FlowLayout.CENTER
  FlowLayout.LEADING
  FlowLayout.TRAILING
  Parameters:
  
  align - one of the alignment values shown above
  
  Since:
  
  1.1
  
  See Also:
  
  getAlignment()
- getHgap
  
  public int getHgap()
  
  Gets the horizontal gap between components and between the components and the borders of the Container
  Returns:
  
  the horizontal gap between components and between the components and the borders of the Container
  
  Since:
  
  1.1
  
  See Also:
  
  setHgap(int)
- setHgap
  
  public void setHgap(int hgap)
  
  Sets the horizontal gap between components and between the components and the borders of the Container.
  Parameters:
  
  hgap - the horizontal gap between components and between the components and the borders of the Container
  
  Since:
  
  1.1
  
  See Also:
  
  getHgap()
- getVgap
  
  public int getVgap()
  
  Gets the vertical gap between components and between the components and the borders of the Container.
  Returns:
  
  the vertical gap between components and between the components and the borders of the Container
  
  Since:
  
  1.1
  
  See Also:
  
  setVgap(int)
- setVgap
  
  public void setVgap(int vgap)
  
  Sets the vertical gap between components and between the components and the borders of the Container.
  Parameters:
  
  vgap - the vertical gap between components and between the components and the borders of the Container
  
  Since:
  
  1.1
  
  See Also:
  
  getVgap()
- setAlignOnBaseline
  
  public void setAlignOnBaseline(boolean alignOnBaseline)
  
  Sets whether or not components should be vertically aligned along their baseline. Components that do not have a baseline will be centered. The default is false.
  
  Parameters:
  
  alignOnBaseline - whether or not components should be vertically aligned on their baseline
  
  Since:
  
  1.6
- getAlignOnBaseline
  
  public boolean getAlignOnBaseline()
  
  Returns true if components are to be vertically aligned along their baseline. The default is false.
  
  Returns:
  
  true if components are to be vertically aligned along their baseline
  
  Since:
  
  1.6
- 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 visible components in the specified target container.
  Specified by:
  
  preferredLayoutSize in interface LayoutManager
  
  Parameters:
  
  target - the container that 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 visible components contained in the specified target container.
  Specified by:
  
  minimumLayoutSize in interface LayoutManager
  
  Parameters:
  
  target - the container that 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 visible component take its preferred size by reshaping the components in the target container in order to satisfy the alignment 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.
  
  Overrides:
  
  toString in class Object
  
  Returns:
  
  a string representation of this layout

Class FlowLayout

Field Summary

Constructor Summary

Method Summary

Methods declared in class java.lang.Object

Field Details

LEFT

CENTER

RIGHT

LEADING

TRAILING

Constructor Details

FlowLayout

FlowLayout

FlowLayout

Method Details

getAlignment

setAlignment

getHgap

setHgap

getVgap

setVgap

setAlignOnBaseline

getAlignOnBaseline

addLayoutComponent

removeLayoutComponent

preferredLayoutSize

minimumLayoutSize

layoutContainer

toString