OpenJDK 27 · java.awt.FlowLayout · APIdia, the JavaDoc alternative

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:

For example, the following picture shows a window 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 program:

import java.awt.Button;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Frame;

public class FlowLayoutExample {

    public static void main(String[] args) throws Exception {
        EventQueue.invokeAndWait(() -> {
            Frame frame = new Frame("FlowLayout");
            frame.setLayout(new FlowLayout());
            frame.add(new Button("OK"));
            frame.add(new Button("Open"));
            frame.add(new Button("Close"));
            frame.pack();
            frame.setVisible(true);
        });
    }
}

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

Field Summary

Modifier and Type	Field and Description
pack-priv int	align `align` is the property that determines how each row distributes empty space.
private boolean	alignOnBaseline
public static final int	CENTER This value indicates that each row of components should be centered.
private static final int	currentSerialVersion
pack-priv int	hgap The flow layout manager allows a separation of components with gaps.
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.
public static final int	LEFT This value indicates that each row of components should be left-justified.
pack-priv int	newAlign `newAlign` is the property that determines how each row distributes empty space for the Java 2 platform, v1.2 and greater.
public static final int	RIGHT This value indicates that each row of components should be right-justified.
private int	serialVersionOnStream This represents the `currentSerialVersion` which is being used.
private static final long	serialVersionUID Use serialVersionUID from JDK 1.1 for interoperability.
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.
pack-priv int	vgap The flow layout manager allows a separation of components with gaps.

Constructor Summary

Access	Constructor and Description
public	FlowLayout() Constructs a new `FlowLayout` with a centered alignment and a default 5-unit horizontal and vertical gap.
public	FlowLayout(int the alignment value align) Constructs a new `FlowLayout` with the specified alignment and a default 5-unit horizontal and vertical gap.
public	FlowLayout(int the alignment value align, int the horizontal gap between components and between the components and the borders of the `Container` hgap, int the vertical gap between components and between the components and the borders of the `Container` vgap) Creates a new flow layout manager with the indicated alignment and the indicated horizontal and vertical gaps.

Method Summary

Modifier and Type	Method and Description
public void	addLayoutComponent(String the name of the component name, Component the component to be added comp) Implements java.awt.LayoutManager.addLayoutComponent. Adds the specified component to the layout.
public int	Returns: the alignment value for this layout getAlignment() Gets the alignment for this layout.
public boolean	Returns: true if components are to be vertically aligned along their baseline getAlignOnBaseline() Returns true if components are to be vertically aligned along their baseline.
public int	Returns: the horizontal gap between components and between the components and the borders of the `Container` getHgap() Gets the horizontal gap between components and between the components and the borders of the `Container`
public int	Returns: the vertical gap between components and between the components and the borders of the `Container` getVgap() Gets the vertical gap between components and between the components and the borders of the `Container`.
public void	layoutContainer(Container the specified component being laid out target) Implements java.awt.LayoutManager.layoutContainer. Lays out the container.
public Dimension	Returns: the minimum dimensions to lay out the subcomponents of the specified container minimumLayoutSize(Container the container that needs to be laid out target) Implements java.awt.LayoutManager.minimumLayoutSize. Returns the minimum dimensions needed to layout the visible components contained in the specified target container.
private int	Returns: actual row height moveComponents(Container the component which needs to be moved target, int the x coordinate x, int the y coordinate y, int the width dimensions width, int the height dimensions height, int the beginning of the row rowStart, int the ending of the row rowEnd, boolean ltr, boolean Whether or not to align on baseline. useBaseline, int[] Ascent for the components. This is only valid if useBaseline is true. ascent, int[] Ascent for the components. This is only valid if useBaseline is true. descent) Centers the elements in the specified row, if there is any slack.
public Dimension	Returns: the preferred dimensions to lay out the subcomponents of the specified container preferredLayoutSize(Container the container that needs to be laid out target) Implements java.awt.LayoutManager.preferredLayoutSize. Returns the preferred dimensions for this layout given the visible components in the specified target container.
private void	readObject(ObjectInputStream the `ObjectInputStream` to read stream) Reads this object out of a serialization stream, handling objects written by older versions of the class that didn't contain all of the fields we use now.
public void	removeLayoutComponent(Component the component to remove comp) Implements java.awt.LayoutManager.removeLayoutComponent. Removes the specified component from the layout.
public void	setAlignment(int one of the alignment values shown above align) Sets the alignment for this layout.
public void	setAlignOnBaseline(boolean whether or not components should be vertically aligned on their baseline alignOnBaseline) Sets whether or not components should be vertically aligned along their baseline.
public void	setHgap(int the horizontal gap between components and between the components and the borders of the `Container` hgap) Sets the horizontal gap between components and between the components and the borders of the `Container`.
public void	setVgap(int the vertical gap between components and between the components and the borders of the `Container` vgap) Sets the vertical gap between components and between the components and the borders of the `Container`.
public String	Returns: a string representation of this layout toString() Overrides java.lang.Object.toString. Returns a string representation of this `FlowLayout` object and its values.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll wait wait wait

Field Detail

align back to summary

align	back to summary
pack-priv int align `align` is the property that determines how each row distributes empty space. It can be one of the following values: `LEFT` `RIGHT` `CENTER` See Also `getAlignment`, `setAlignment`

pack-priv int align

align is the property that determines how each row distributes empty space. It can be one of the following values:

LEFT
RIGHT
CENTER

See Also: getAlignment, setAlignment

alignOnBaseline	back to summary
private boolean alignOnBaseline

CENTER	back to summary
public static final int CENTER This value indicates that each row of components should be centered.

currentSerialVersion	back to summary
private static final int currentSerialVersion

hgap back to summary

hgap	back to summary
pack-priv int hgap The flow layout manager allows a separation of components with gaps. The horizontal gap will specify the space between components and between the components and the borders of the `Container`. See Also `getHgap()`, `setHgap(int)`

pack-priv int hgap

The flow layout manager allows a separation of components with gaps. The horizontal gap will specify the space between components and between the components and the borders of the Container.

See Also: getHgap(), setHgap(int)

LEADING back to summary

LEADING	back to summary
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 `java.awt.Component#getComponentOrientation`, `java.awt.ComponentOrientation`

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: java.awt.Component#getComponentOrientation, java.awt.ComponentOrientation

LEFT	back to summary
public static final int LEFT This value indicates that each row of components should be left-justified.

newAlign back to summary

newAlign	back to summary
pack-priv int newAlign `newAlign` is the property that determines how each row distributes empty space for the Java 2 platform, v1.2 and greater. It can be one of the following three values: `LEFT` `RIGHT` `CENTER` `LEADING` `TRAILING` Since 1.2 See Also `getAlignment`, `setAlignment`

pack-priv int newAlign

newAlign is the property that determines how each row distributes empty space for the Java 2 platform, v1.2 and greater. It can be one of the following three values:

LEFT
RIGHT
CENTER
LEADING
TRAILING

Since: 1.2
See Also: getAlignment, setAlignment

RIGHT	back to summary
public static final int RIGHT This value indicates that each row of components should be right-justified.

serialVersionOnStream back to summary

serialVersionOnStream	back to summary
private int serialVersionOnStream This represents the `currentSerialVersion` which is being used. It will be one of two values: `0` versions before Java 2 platform v1.2, `1` versions after Java 2 platform v1.2. Since 1.2

private int serialVersionOnStream

This represents the currentSerialVersion which is being used. It will be one of two values: 0 versions before Java 2 platform v1.2, 1 versions after Java 2 platform v1.2.

Since: 1.2

serialVersionUID	back to summary
private static final long serialVersionUID Use serialVersionUID from JDK 1.1 for interoperability. Annotations @Serial

TRAILING back to summary

TRAILING	back to summary
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 `java.awt.Component#getComponentOrientation`, `java.awt.ComponentOrientation`

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: java.awt.Component#getComponentOrientation, java.awt.ComponentOrientation

vgap back to summary

vgap	back to summary
pack-priv int vgap The flow layout manager allows a separation of components with gaps. The vertical gap will specify the space between rows and between the the rows and the borders of the `Container`. See Also `getHgap()`, `setHgap(int)`

pack-priv int vgap

The flow layout manager allows a separation of components with gaps. The vertical gap will specify the space between rows and between the the rows and the borders of the Container.

See Also: getHgap(), setHgap(int)

Constructor Detail

FlowLayout	back to summary
public FlowLayout() Constructs a new `FlowLayout` with a centered alignment and a default 5-unit horizontal and vertical gap.

FlowLayout back to summary

FlowLayout	back to summary
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:int the alignment value

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:int: the alignment value

FlowLayout back to summary

FlowLayout	back to summary
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:int the alignment value hgap:int the horizontal gap between components and between the components and the borders of the `Container` vgap:int the vertical gap between components and between the components and the borders of the `Container`

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:int: the alignment value
hgap:int: the horizontal gap between components and between the components and the borders of the Container
vgap:int: the vertical gap between components and between the components and the borders of the Container

Method Detail

addLayoutComponent	back to summary
public void addLayoutComponent(String name, Component comp) Implements java.awt.LayoutManager.addLayoutComponent. Adds the specified component to the layout. Not used by this class. Parameters name:String the name of the component comp:Component the component to be added

addLayoutComponent

back to summary

public void addLayoutComponent(String name, Component comp)

Implements java.awt.LayoutManager.addLayoutComponent.

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

Parameters

name:String: the name of the component
comp:Component: the component to be added

getAlignment back to summary

getAlignment	back to summary
public int getAlignment() Gets the alignment for this layout. Possible values are `FlowLayout.LEFT`, `FlowLayout.RIGHT`, `FlowLayout.CENTER`, `FlowLayout.LEADING`, or `FlowLayout.TRAILING`. Returns:int the alignment value for this layout Since 1.1 See Also `java.awt.FlowLayout#setAlignment`

public int getAlignment()

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

Returns:int: the alignment value for this layout
Since: 1.1
See Also: java.awt.FlowLayout#setAlignment

getAlignOnBaseline	back to summary
public boolean getAlignOnBaseline() Returns true if components are to be vertically aligned along their baseline. The default is false. Returns:boolean true if components are to be vertically aligned along their baseline Since 1.6

getAlignOnBaseline

back to summary

public boolean getAlignOnBaseline()

Returns true if components are to be vertically aligned along their baseline. The default is false.

Returns:boolean: true if components are to be vertically aligned along their baseline
Since: 1.6

getHgap back to summary

getHgap	back to summary
public int getHgap() Gets the horizontal gap between components and between the components and the borders of the `Container` Returns:int the horizontal gap between components and between the components and the borders of the `Container` Since 1.1 See Also `java.awt.FlowLayout#setHgap`

public int getHgap()

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

Returns:int: the horizontal gap between components and between the components and the borders of the Container
Since: 1.1
See Also: java.awt.FlowLayout#setHgap

getVgap back to summary

getVgap	back to summary
public int getVgap() Gets the vertical gap between components and between the components and the borders of the `Container`. Returns:int the vertical gap between components and between the components and the borders of the `Container` Since 1.1 See Also `java.awt.FlowLayout#setVgap`

public int getVgap()

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

Returns:int: the vertical gap between components and between the components and the borders of the Container
Since: 1.1
See Also: java.awt.FlowLayout#setVgap

layoutContainer back to summary

layoutContainer	back to summary
public void layoutContainer(Container target) Implements java.awt.LayoutManager.layoutContainer. 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. Parameters target:Container the specified component being laid out See Also `Container`, `java.awt.Container#doLayout`

public void layoutContainer(Container target)

Implements java.awt.LayoutManager.layoutContainer.

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.

Parameters

target:Container: the specified component being laid out

minimumLayoutSize back to summary

minimumLayoutSize	back to summary
public Dimension minimumLayoutSize(Container target) Implements java.awt.LayoutManager.minimumLayoutSize. Returns the minimum dimensions needed to layout the visible components contained in the specified target container. Parameters target:Container the container that needs to be laid out Returns:Dimension the minimum dimensions to lay out the subcomponents of the specified container See Also `preferredLayoutSize`, `java.awt.Container`, `java.awt.Container#doLayout`

public Dimension minimumLayoutSize(Container target)

Implements java.awt.LayoutManager.minimumLayoutSize.

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

Parameters

target:Container: the container that needs to be laid out

Returns:Dimension

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

moveComponents	back to summary
private int moveComponents(Container target, int x, int y, int width, int height, int rowStart, int rowEnd, boolean ltr, boolean useBaseline, int[] ascent, int[] descent) Centers the elements in the specified row, if there is any slack. Parameters target:Container the component which needs to be moved x:int the x coordinate y:int the y coordinate width:int the width dimensions height:int the height dimensions rowStart:int the beginning of the row rowEnd:int the ending of the row useBaseline:boolean Whether or not to align on baseline. ascent:int[] Ascent for the components. This is only valid if useBaseline is true. descent:int[] Ascent for the components. This is only valid if useBaseline is true. Returns:int actual row height

moveComponents

back to summary

private int moveComponents(Container target, int x, int y, int width, int height, int rowStart, int rowEnd, boolean ltr, boolean useBaseline, int[] ascent, int[] descent)

Centers the elements in the specified row, if there is any slack.

Parameters

target:Container: the component which needs to be moved
x:int: the x coordinate
y:int: the y coordinate
width:int: the width dimensions
height:int: the height dimensions
rowStart:int: the beginning of the row
rowEnd:int: the ending of the row
useBaseline:boolean: Whether or not to align on baseline.
ascent:int[]: Ascent for the components. This is only valid if useBaseline is true.
descent:int[]: Ascent for the components. This is only valid if useBaseline is true.

Returns:int

actual row height

preferredLayoutSize back to summary

preferredLayoutSize	back to summary
public Dimension preferredLayoutSize(Container target) Implements java.awt.LayoutManager.preferredLayoutSize. Returns the preferred dimensions for this layout given the visible components in the specified target container. Parameters target:Container the container that needs to be laid out Returns:Dimension the preferred dimensions to lay out the subcomponents of the specified container See Also `Container`, `minimumLayoutSize`, `java.awt.Container#getPreferredSize`

public Dimension preferredLayoutSize(Container target)

Implements java.awt.LayoutManager.preferredLayoutSize.

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

Parameters

target:Container: the container that needs to be laid out

Returns:Dimension

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

readObject back to summary

readObject	back to summary
private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException Reads this object out of a serialization stream, handling objects written by older versions of the class that didn't contain all of the fields we use now. Parameters stream:ObjectInputStream the `ObjectInputStream` to read Annotations @Serial Exceptions IOException: if an I/O error occurs ClassNotFoundException: if the class of a serialized object could not be found

private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException

Reads this object out of a serialization stream, handling objects written by older versions of the class that didn't contain all of the fields we use now.

Parameters

stream:ObjectInputStream: the ObjectInputStream to read

Annotations

@Serial

Exceptions

IOException:: if an I/O error occurs
ClassNotFoundException:: if the class of a serialized object could not be found

removeLayoutComponent back to summary

removeLayoutComponent	back to summary
public void removeLayoutComponent(Component comp) Implements java.awt.LayoutManager.removeLayoutComponent. Removes the specified component from the layout. Not used by this class. Parameters comp:Component the component to remove See Also `java.awt.Container#removeAll`

public void removeLayoutComponent(Component comp)

Implements java.awt.LayoutManager.removeLayoutComponent.

Removes the specified component from the layout. Not used by this class.

Parameters

comp:Component: the component to remove

See Also

java.awt.Container#removeAll

setAlignment back to summary

setAlignment	back to summary
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:int one of the alignment values shown above Since 1.1 See Also `getAlignment()`

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:int: one of the alignment values shown above

Since

1.1

See Also

getAlignment()

setAlignOnBaseline	back to summary
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:boolean whether or not components should be vertically aligned on their baseline Since 1.6

setAlignOnBaseline

back to summary

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:boolean: whether or not components should be vertically aligned on their baseline

Since

1.6

setHgap back to summary

setHgap	back to summary
public void setHgap(int hgap) Sets the horizontal gap between components and between the components and the borders of the `Container`. Parameters hgap:int the horizontal gap between components and between the components and the borders of the `Container` Since 1.1 See Also `java.awt.FlowLayout#getHgap`

public void setHgap(int hgap)

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

Parameters

hgap:int: the horizontal gap between components and between the components and the borders of the Container

Since

1.1

See Also

java.awt.FlowLayout#getHgap

setVgap back to summary

setVgap	back to summary
public void setVgap(int vgap) Sets the vertical gap between components and between the components and the borders of the `Container`. Parameters vgap:int the vertical gap between components and between the components and the borders of the `Container` Since 1.1 See Also `java.awt.FlowLayout#getVgap`

public void setVgap(int vgap)

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

Parameters

vgap:int: the vertical gap between components and between the components and the borders of the Container

Since

1.1

See Also

java.awt.FlowLayout#getVgap

toString back to summary

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Returns a string representation of this `FlowLayout` object and its values. Returns:String a string representation of this layout

public String toString()

Overrides java.lang.Object.toString.

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

Returns:String: a string representation of this layout

public Class FlowLayout

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail