Class java.awt.FlowLayout - JDK 5 Documentation v1.1.8, Java 2 SDK 英文文档

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Class java.awt.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:

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.

CENTER: This value indicates that each row of components should be centered.
LEFT: This value indicates that each row of components should be left-justified.
RIGHT: This value indicates that each row of components should be right-justified.

FlowLayout(): Constructs a new Flow Layout with a centered alignment and a default 5-unit horizontal and vertical gap.
FlowLayout(int): Constructs a new Flow Layout with the specified alignment and a default 5-unit horizontal and vertical gap.
FlowLayout(int, int, int): Creates a new flow layout manager with the indicated alignment and the indicated horizontal and vertical gaps.

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

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.

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.

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.
See Also:: setAlignment

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.
See Also:: getAlignment

getHgap

 public int getHgap()

Gets the horizontal gap between components.

Returns:: the horizontal gap between components.
See Also:: setHgap

setHgap

 public void setHgap(int hgap)

Sets the horizontal gap between components.

Parameters:: hgap - the horizontal gap between components
See Also:: getHgap

getVgap

 public int getVgap()

Gets the vertical gap between components.

Returns:: the vertical gap between components.
See Also:: setVgap

setVgap

 public void setVgap(int vgap)

Sets the vertical gap between components.

Parameters:: vgap - the vertical gap between components
See Also:: getVgap

addLayoutComponent

 public void addLayoutComponent(String name,
                                Component comp)

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

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.

Parameters:: comp - the component to remove
See Also:: removeAll

preferredLayoutSize

 public Dimension preferredLayoutSize(Container target)

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

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, getPreferredSize

minimumLayoutSize

 public Dimension minimumLayoutSize(Container target)

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

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, 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.

Parameters:: target - the specified component being laid out.
See Also:: 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

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