java.awt

## Class GridBagLayout

- java.lang.Object
- - java.awt.GridBagLayout

- All Implemented Interfaces:
    LayoutManager, LayoutManager2, Serializable

      public class GridBagLayout
      extends Object
      implements LayoutManager2, Serializable

  The `GridBagLayout` class is a flexible layout manager that aligns components vertically, horizontally or along their baseline without requiring that the components be of the same size. Each `GridBagLayout` object maintains a dynamic, rectangular grid of cells, with each component occupying one or more cells, called its display area.

  Each component managed by a `GridBagLayout` is associated with an instance of `GridBagConstraints`. The constraints object specifies where a component's display area should be located on the grid and how the component should be positioned within its display area. In addition to its constraints object, the `GridBagLayout` also considers each component's minimum and preferred sizes in order to determine a component's size.

  The overall orientation of the grid depends on the container's `ComponentOrientation` property. For horizontal left-to-right orientations, grid coordinate (0,0) is in the upper left corner of the container with x increasing to the right and y increasing downward. For horizontal right-to-left orientations, grid coordinate (0,0) is in the upper right corner of the container with x increasing to the left and y increasing downward.

  To use a grid bag layout effectively, you must customize one or more of the `GridBagConstraints` objects that are associated with its components. You customize a `GridBagConstraints` object by setting one or more of its instance variables:

  `GridBagConstraints.gridx`, `GridBagConstraints.gridy`
    Specifies the cell containing the leading corner of the component's display area, where the cell at the origin of the grid has address `gridx = 0`, `gridy = 0`. For horizontal left-to-right layout, a component's leading corner is its upper left. For horizontal right-to-left layout, a component's leading corner is its upper right. Use `GridBagConstraints.RELATIVE` (the default value) to specify that the component be placed immediately following (along the x axis for `gridx` or the y axis for `gridy`) the component that was added to the container just before this component was added.
  `GridBagConstraints.gridwidth`, `GridBagConstraints.gridheight`
    Specifies the number of cells in a row (for `gridwidth`) or column (for `gridheight`) in the component's display area. The default value is 1. Use `GridBagConstraints.REMAINDER` to specify that the component's display area will be from `gridx` to the last cell in the row (for `gridwidth`) or from `gridy` to the last cell in the column (for `gridheight`). Use `GridBagConstraints.RELATIVE` to specify that the component's display area will be from `gridx` to the next to the last cell in its row (for `gridwidth` or from `gridy` to the next to the last cell in its column (for `gridheight`).
  `GridBagConstraints.fill`
    Used when the component's display area is larger than the component's requested size to determine whether (and how) to resize the component. Possible values are `GridBagConstraints.NONE` (the default), `GridBagConstraints.HORIZONTAL` (make the component wide enough to fill its display area horizontally, but don't change its height), `GridBagConstraints.VERTICAL` (make the component tall enough to fill its display area vertically, but don't change its width), and `GridBagConstraints.BOTH` (make the component fill its display area entirely).
  `GridBagConstraints.ipadx`, `GridBagConstraints.ipady`
    Specifies the component's internal padding within the layout, how much to add to the minimum size of the component. The width of the component will be at least its minimum width plus `ipadx` pixels. Similarly, the height of the component will be at least the minimum height plus `ipady` pixels.
  `GridBagConstraints.insets`
    Specifies the component's external padding, the minimum amount of space between the component and the edges of its display area.
  `GridBagConstraints.anchor`
    Specifies where the component should be positioned in its display area. There are three kinds of possible values: absolute, orientation-relative, and baseline-relative Orientation relative values are interpreted relative to the container's `ComponentOrientation` property while absolute values are not. Baseline relative values are calculated relative to the baseline. Valid values are:

    Absolute Values | Orientation Relative Values | Baseline Relative Values
    --- | --- | ---
    `GridBagConstraints.NORTH` `GridBagConstraints.SOUTH` `GridBagConstraints.WEST` `GridBagConstraints.EAST` `GridBagConstraints.NORTHWEST` `GridBagConstraints.NORTHEAST` `GridBagConstraints.SOUTHWEST` `GridBagConstraints.SOUTHEAST` `GridBagConstraints.CENTER` (the default) | `GridBagConstraints.PAGE_START` `GridBagConstraints.PAGE_END` `GridBagConstraints.LINE_START` `GridBagConstraints.LINE_END` `GridBagConstraints.FIRST_LINE_START` `GridBagConstraints.FIRST_LINE_END` `GridBagConstraints.LAST_LINE_START` `GridBagConstraints.LAST_LINE_END` | `GridBagConstraints.BASELINE` `GridBagConstraints.BASELINE_LEADING` `GridBagConstraints.BASELINE_TRAILING` `GridBagConstraints.ABOVE_BASELINE` `GridBagConstraints.ABOVE_BASELINE_LEADING` `GridBagConstraints.ABOVE_BASELINE_TRAILING` `GridBagConstraints.BELOW_BASELINE` `GridBagConstraints.BELOW_BASELINE_LEADING` `GridBagConstraints.BELOW_BASELINE_TRAILING`

  `GridBagConstraints.weightx`, `GridBagConstraints.weighty`
    Used to determine how to distribute space, which is important for specifying resizing behavior. Unless you specify a weight for at least one component in a row (`weightx`) and column (`weighty`), all the components clump together in the center of their container. This is because when the weight is zero (the default), the `GridBagLayout` object puts any extra space between its grid of cells and the edges of the container.

  Each row may have a baseline; the baseline is determined by the components in that row that have a valid baseline and are aligned along the baseline (the component's anchor value is one of `BASELINE`, `BASELINE_LEADING` or `BASELINE_TRAILING`). If none of the components in the row has a valid baseline, the row does not have a baseline.

  If a component spans rows it is aligned either to the baseline of the start row (if the baseline-resize behavior is `CONSTANT_ASCENT`) or the end row (if the baseline-resize behavior is `CONSTANT_DESCENT`). The row that the component is aligned to is called the prevailing row.

  The following figure shows a baseline layout and includes a component that spans rows:

  This layout consists of three components:
  - A panel that starts in row 0 and ends in row 1. The panel has a baseline-resize behavior of `CONSTANT_DESCENT` and has an anchor of `BASELINE`. As the baseline-resize behavior is `CONSTANT_DESCENT` the prevailing row for the panel is row 1.
  - Two buttons, each with a baseline-resize behavior of `CENTER_OFFSET` and an anchor of `BASELINE`.
  Because the second button and the panel share the same prevailing row, they are both aligned along their baseline.

  Components positioned using one of the baseline-relative values resize differently than when positioned using an absolute or orientation-relative value. How components change is dictated by how the baseline of the prevailing row changes. The baseline is anchored to the bottom of the display area if any components with the same prevailing row have a baseline-resize behavior of `CONSTANT_DESCENT`, otherwise the baseline is anchored to the top of the display area. The following rules dictate the resize behavior:

  - Resizable components positioned above the baseline can only grow as tall as the baseline. For example, if the baseline is at 100 and anchored at the top, a resizable component positioned above the baseline can never grow more than 100 units.
  - Similarly, resizable components positioned below the baseline can only grow as high as the difference between the display height and the baseline.
  - Resizable components positioned on the baseline with a baseline-resize behavior of `OTHER` are only resized if the baseline at the resized size fits within the display area. If the baseline is such that it does not fit within the display area the component is not resized.
  - Components positioned on the baseline that do not have a baseline-resize behavior of `OTHER` can only grow as tall as `display height - baseline + baseline of component`.
  If you position a component along the baseline, but the component does not have a valid baseline, it will be vertically centered in its space. Similarly if you have positioned a component relative to the baseline and none of the components in the row have a valid baseline the component is vertically centered.

  The following figures show ten components (all buttons) managed by a grid bag layout. Figure 2 shows the layout for a horizontal, left-to-right container and Figure 3 shows the layout for a horizontal, right-to-left container.

  Figure 2: Horizontal, Left-to-Right | Figure 3: Horizontal, Right-to-Left

  Each of the ten components has the `fill` field of its associated `GridBagConstraints` object set to `GridBagConstraints.BOTH`. In addition, the components have the following non-default constraints:

  - Button1, Button2, Button3: `weightx = 1.0`
  - Button4: `weightx = 1.0`, `gridwidth = GridBagConstraints.REMAINDER`
  - Button5: `gridwidth = GridBagConstraints.REMAINDER`
  - Button6: `gridwidth = GridBagConstraints.RELATIVE`
  - Button7: `gridwidth = GridBagConstraints.REMAINDER`
  - Button8: `gridheight = 2`, `weighty = 1.0`
  - Button9, Button 10: `gridwidth = GridBagConstraints.REMAINDER`

  Here is the code that implements the example shown above:

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

  >      public class GridBagEx1 extends Applet {

  >          protected void makebutton(String name,
  >                                    GridBagLayout gridbag,
  >                                    GridBagConstraints c) {
  >              Button button = new Button(name);
  >              gridbag.setConstraints(button, c);
  >              add(button);
  >          }

  >          public void init() {
  >              GridBagLayout gridbag = new GridBagLayout();
  >              GridBagConstraints c = new GridBagConstraints();

  >              setFont(new Font("SansSerif", Font.PLAIN, 14));
  >              setLayout(gridbag);

  >              c.fill = GridBagConstraints.BOTH;
  >              c.weightx = 1.0;
  >              makebutton("Button1", gridbag, c);
  >              makebutton("Button2", gridbag, c);
  >              makebutton("Button3", gridbag, c);

  >              c.gridwidth = GridBagConstraints.REMAINDER; //end row
  >              makebutton("Button4", gridbag, c);

  >              c.weightx = 0.0;                //reset to the default
  >              makebutton("Button5", gridbag, c); //another row

  >              c.gridwidth = GridBagConstraints.RELATIVE; //next-to-last in row
  >              makebutton("Button6", gridbag, c);

  >              c.gridwidth = GridBagConstraints.REMAINDER; //end row
  >              makebutton("Button7", gridbag, c);

  >              c.gridwidth = 1;                //reset to the default
  >              c.gridheight = 2;
  >              c.weighty = 1.0;
  >              makebutton("Button8", gridbag, c);

  >              c.weighty = 0.0;                //reset to the default
  >              c.gridwidth = GridBagConstraints.REMAINDER; //end row
  >              c.gridheight = 1;               //reset to the default
  >              makebutton("Button9", gridbag, c);
  >              makebutton("Button10", gridbag, c);

  >              setSize(300, 100);
  >          }

  >          public static void main(String args[]) {
  >              Frame f = new Frame("GridBag Layout Example");
  >              GridBagEx1 ex1 = new GridBagEx1();

  >              ex1.init();

  >              f.add("Center", ex1);
  >              f.pack();
  >              f.setSize(f.getPreferredSize());
  >              f.show();
  >          }
  >      }

  Since:
    JDK1.0
  See Also:
    `GridBagConstraints`, `GridBagLayoutInfo`, `ComponentOrientation`, Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `double[]` | `columnWeights` This field holds the overrides to the column weights.
    `int[]` | `columnWidths` This field holds the overrides to the column minimum width.
    `protected Hashtable<Component,GridBagConstraints>` | `comptable` This hashtable maintains the association between a component and its gridbag constraints.
    `protected GridBagConstraints` | `defaultConstraints` This field holds a gridbag constraints instance containing the default values, so if a component does not have gridbag constraints associated with it, then the component will be assigned a copy of the `defaultConstraints`.
    `protected GridBagLayoutInfo` | `layoutInfo` This field holds the layout information for the gridbag.
    `protected static int` | `MAXGRIDSIZE` This field is no longer used to reserve arrays and kept for backward compatibility.
    `protected static int` | `MINSIZE` The smallest grid that can be laid out by the grid bag layout.
    `protected static int` | `PREFERREDSIZE` The preferred grid size that can be laid out by the grid bag layout.
    `int[]` | `rowHeights` This field holds the overrides to the row minimum heights.
    `double[]` | `rowWeights` This field holds the overrides to the row weights.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `GridBagLayout()` Creates a grid bag layout manager.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addLayoutComponent(Component comp, Object constraints)` Adds the specified component to the layout, using the specified `constraints` object.
    `void` | `addLayoutComponent(String name, Component comp)` Has no effect, since this layout manager does not use a per-component string.
    `protected void` | `adjustForGravity(GridBagConstraints constraints, Rectangle r)` Adjusts the x, y, width, and height fields to the correct values depending on the constraint geometry and pads.
    `protected void` | `AdjustForGravity(GridBagConstraints constraints, Rectangle r)` This method is obsolete and supplied for backwards compatibility only; new code should call `adjustForGravity` instead.
    `protected void` | `arrangeGrid(Container parent)` Lays out the grid.
    `protected void` | `ArrangeGrid(Container parent)` This method is obsolete and supplied for backwards compatibility only; new code should call `arrangeGrid` instead.
    `GridBagConstraints` | `getConstraints(Component comp)` Gets the constraints for the specified component.
    `float` | `getLayoutAlignmentX(Container parent)` Returns the alignment along the x axis.
    `float` | `getLayoutAlignmentY(Container parent)` Returns the alignment along the y axis.
    `int[][]` | `getLayoutDimensions()` Determines column widths and row heights for the layout grid.
    `protected GridBagLayoutInfo` | `getLayoutInfo(Container parent, int sizeflag)` Fills in an instance of `GridBagLayoutInfo` for the current set of managed children.
    `protected GridBagLayoutInfo` | `GetLayoutInfo(Container parent, int sizeflag)` This method is obsolete and supplied for backwards compatibility only; new code should call `getLayoutInfo` instead.
    `Point` | `getLayoutOrigin()` Determines the origin of the layout area, in the graphics coordinate space of the target container.
    `double[][]` | `getLayoutWeights()` Determines the weights of the layout grid's columns and rows.
    `protected Dimension` | `getMinSize(Container parent, GridBagLayoutInfo info)` Figures out the minimum size of the master based on the information from `getLayoutInfo`.
    `protected Dimension` | `GetMinSize(Container parent, GridBagLayoutInfo info)` This method is obsolete and supplied for backwards compatibility only; new code should call `getMinSize` instead.
    `void` | `invalidateLayout(Container target)` Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.
    `void` | `layoutContainer(Container parent)` Lays out the specified container using this grid bag layout.
    `Point` | `location(int x, int y)` Determines which cell in the layout grid contains the point specified by `(x, y)`.
    `protected GridBagConstraints` | `lookupConstraints(Component comp)` Retrieves the constraints for the specified component.
    `Dimension` | `maximumLayoutSize(Container target)` Returns the maximum dimensions for this layout given the components in the specified target container.
    `Dimension` | `minimumLayoutSize(Container parent)` Determines the minimum size of the `parent` container using this grid bag layout.
    `Dimension` | `preferredLayoutSize(Container parent)` Determines the preferred size of the `parent` container using this grid bag layout.
    `void` | `removeLayoutComponent(Component comp)` Removes the specified component from this layout.
    `void` | `setConstraints(Component comp, GridBagConstraints constraints)` Sets the constraints for the specified component in this layout.
    `String` | `toString()` Returns a string representation of this grid bag layout's values.

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### MAXGRIDSIZE

          protected static final int MAXGRIDSIZE

      This field is no longer used to reserve arrays and kept for backward compatibility. Previously, this was the maximum number of grid positions (both horizontal and vertical) that could be laid out by the grid bag layout. Current implementation doesn't impose any limits on the size of a grid.
      See Also:
        Constant Field Values

    - #### MINSIZE

          protected static final int MINSIZE

      The smallest grid that can be laid out by the grid bag layout.
      See Also:
        Constant Field Values

    - #### PREFERREDSIZE

          protected static final int PREFERREDSIZE

      The preferred grid size that can be laid out by the grid bag layout.
      See Also:
        Constant Field Values

    - #### comptable

          protected Hashtable<Component,GridBagConstraints> comptable

      This hashtable maintains the association between a component and its gridbag constraints. The Keys in `comptable` are the components and the values are the instances of `GridBagConstraints`.
      See Also:
        `GridBagConstraints`

    - #### defaultConstraints

          protected GridBagConstraints defaultConstraints

      This field holds a gridbag constraints instance containing the default values, so if a component does not have gridbag constraints associated with it, then the component will be assigned a copy of the `defaultConstraints`.
      See Also:
        `getConstraints(Component)`, `setConstraints(Component, GridBagConstraints)`, `lookupConstraints(Component)`

    - #### layoutInfo

          protected GridBagLayoutInfo layoutInfo

      This field holds the layout information for the gridbag. The information in this field is based on the most recent validation of the gridbag. If `layoutInfo` is `null` this indicates that there are no components in the gridbag or if there are components, they have not yet been validated.
      See Also:
        `getLayoutInfo(Container, int)`

    - #### columnWidths

          public int[] columnWidths

      This field holds the overrides to the column minimum width. If this field is non-`null` the values are applied to the gridbag after all of the minimum columns widths have been calculated. If columnWidths has more elements than the number of columns, columns are added to the gridbag to match the number of elements in columnWidth.
      See Also:
        `getLayoutDimensions()`

    - #### rowHeights

          public int[] rowHeights

      This field holds the overrides to the row minimum heights. If this field is non-`null` the values are applied to the gridbag after all of the minimum row heights have been calculated. If `rowHeights` has more elements than the number of rows, rows are added to the gridbag to match the number of elements in `rowHeights`.
      See Also:
        `getLayoutDimensions()`

    - #### columnWeights

          public double[] columnWeights

      This field holds the overrides to the column weights. If this field is non-`null` the values are applied to the gridbag after all of the columns weights have been calculated. If `columnWeights[i]` > weight for column i, then column i is assigned the weight in `columnWeights[i]`. If `columnWeights` has more elements than the number of columns, the excess elements are ignored - they do not cause more columns to be created.

    - #### rowWeights

          public double[] rowWeights

      This field holds the overrides to the row weights. If this field is non-`null` the values are applied to the gridbag after all of the rows weights have been calculated. If `rowWeights[i]` > weight for row i, then row i is assigned the weight in `rowWeights[i]`. If `rowWeights` has more elements than the number of rows, the excess elements are ignored - they do not cause more rows to be created.

  - ### Constructor Detail

    - #### GridBagLayout

          public GridBagLayout()

      Creates a grid bag layout manager.

  - ### Method Detail

    - #### setConstraints

          public void setConstraints(Component comp,
                                     GridBagConstraints constraints)

      Sets the constraints for the specified component in this layout.
      Parameters:
        `comp` - the component to be modified
        `constraints` - the constraints to be applied

    - #### getConstraints

          public GridBagConstraints getConstraints(Component comp)

      Gets the constraints for the specified component. A copy of the actual `GridBagConstraints` object is returned.
      Parameters:
        `comp` - the component to be queried
      Returns:
        the constraint for the specified component in this grid bag layout; a copy of the actual constraint object is returned

    - #### lookupConstraints

          protected GridBagConstraints lookupConstraints(Component comp)

      Retrieves the constraints for the specified component. The return value is not a copy, but is the actual `GridBagConstraints` object used by the layout mechanism.

      If `comp` is not in the `GridBagLayout`, a set of default `GridBagConstraints` are returned. A `comp` value of `null` is invalid and returns `null`.

      Parameters:
        `comp` - the component to be queried
      Returns:
        the constraints for the specified component

    - #### getLayoutOrigin

          public Point getLayoutOrigin()

      Determines the origin of the layout area, in the graphics coordinate space of the target container. This value represents the pixel coordinates of the top-left corner of the layout area regardless of the `ComponentOrientation` value of the container. This is distinct from the grid origin given by the cell coordinates (0,0). Most applications do not call this method directly.
      Returns:
        the graphics origin of the cell in the top-left corner of the layout grid
      Since:
        JDK1.1
      See Also:
        `ComponentOrientation`

    - #### getLayoutDimensions

          public int[][] getLayoutDimensions()

      Determines column widths and row heights for the layout grid.

      Most applications do not call this method directly.

      Returns:
        an array of two arrays, containing the widths of the layout columns and the heights of the layout rows
      Since:
        JDK1.1

    - #### getLayoutWeights

          public double[][] getLayoutWeights()

      Determines the weights of the layout grid's columns and rows. Weights are used to calculate how much a given column or row stretches beyond its preferred size, if the layout has extra room to fill.

      Most applications do not call this method directly.

      Returns:
        an array of two arrays, representing the horizontal weights of the layout columns and the vertical weights of the layout rows
      Since:
        JDK1.1

    - #### location

          public Point location(int x,
                                int y)

      Determines which cell in the layout grid contains the point specified by `(x, y)`. Each cell is identified by its column index (ranging from 0 to the number of columns minus 1) and its row index (ranging from 0 to the number of rows minus 1).

      If the `(x, y)` point lies outside the grid, the following rules are used. The column index is returned as zero if `x` lies to the left of the layout for a left-to-right container or to the right of the layout for a right-to-left container. The column index is returned as the number of columns if `x` lies to the right of the layout in a left-to-right container or to the left in a right-to-left container. The row index is returned as zero if `y` lies above the layout, and as the number of rows if `y` lies below the layout. The orientation of a container is determined by its `ComponentOrientation` property.

      Parameters:
        `x` - the x coordinate of a point
        `y` - the y coordinate of a point
      Returns:
        an ordered pair of indexes that indicate which cell in the layout grid contains the point (x, y).
      Since:
        JDK1.1
      See Also:
        `ComponentOrientation`

    - #### addLayoutComponent

          public void addLayoutComponent(String name,
                                         Component comp)

      Has no effect, since this layout manager does not use a per-component string.
      Specified by:
        `addLayoutComponent` in interface `LayoutManager`
      Parameters:
        `name` - the string to be associated with the component
        `comp` - the component to be added

    - #### addLayoutComponent

          public void addLayoutComponent(Component comp,
                                         Object constraints)

      Adds the specified component to the layout, using the specified `constraints` object. Note that constraints are mutable and are, therefore, cloned when cached.
      Specified by:
        `addLayoutComponent` in interface `LayoutManager2`
      Parameters:
        `comp` - the component to be added
        `constraints` - an object that determines how the component is added to the layout
      Throws:
        `IllegalArgumentException` - if `constraints` is not a `GridBagConstraint`

    - #### removeLayoutComponent

          public void removeLayoutComponent(Component comp)

      Removes the specified component from this layout.

      Most applications do not call this method directly.

      Specified by:
        `removeLayoutComponent` in interface `LayoutManager`
      Parameters:
        `comp` - the component to be removed.
      See Also:
        `Container.remove(java.awt.Component)`, `Container.removeAll()`

    - #### preferredLayoutSize

          public Dimension preferredLayoutSize(Container parent)

      Determines the preferred size of the `parent` container using this grid bag layout.

      Most applications do not call this method directly.

      Specified by:
        `preferredLayoutSize` in interface `LayoutManager`
      Parameters:
        `parent` - the container in which to do the layout
      Returns:
        the preferred size of the `parent` container
      See Also:
        `Container.getPreferredSize()`

    - #### minimumLayoutSize

          public Dimension minimumLayoutSize(Container parent)

      Determines the minimum size of the `parent` container using this grid bag layout.

      Most applications do not call this method directly.

      Specified by:
        `minimumLayoutSize` in interface `LayoutManager`
      Parameters:
        `parent` - the container in which to do the layout
      Returns:
        the minimum size of the `parent` container
      See Also:
        `Container.doLayout()`

    - #### maximumLayoutSize

          public Dimension maximumLayoutSize(Container target)

      Returns the maximum dimensions for this layout given the components in the specified target container.
      Specified by:
        `maximumLayoutSize` in interface `LayoutManager2`
      Parameters:
        `target` - the container which needs to be laid out
      Returns:
        the maximum dimensions for this layout
      See Also:
        `Container`, `minimumLayoutSize(Container)`, `preferredLayoutSize(Container)`

    - #### getLayoutAlignmentX

          public float getLayoutAlignmentX(Container parent)

      Returns the alignment along the x axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.

      Specified by:
        `getLayoutAlignmentX` in interface `LayoutManager2`
      Returns:
        the value `0.5f` to indicate centered

    - #### getLayoutAlignmentY

          public float getLayoutAlignmentY(Container parent)

      Returns the alignment along the y axis. This specifies how the component would like to be aligned relative to other components. The value should be a number between 0 and 1 where 0 represents alignment along the origin, 1 is aligned the furthest away from the origin, 0.5 is centered, etc.

      Specified by:
        `getLayoutAlignmentY` in interface `LayoutManager2`
      Returns:
        the value `0.5f` to indicate centered

    - #### invalidateLayout

          public void invalidateLayout(Container target)

      Invalidates the layout, indicating that if the layout manager has cached information it should be discarded.
      Specified by:
        `invalidateLayout` in interface `LayoutManager2`

    - #### layoutContainer

          public void layoutContainer(Container parent)

      Lays out the specified container using this grid bag layout. This method reshapes components in the specified container in order to satisfy the constraints of this `GridBagLayout` object.

      Most applications do not call this method directly.

      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 a string representation of this grid bag layout's values.
      Overrides:
        `toString` in class `Object`
      Returns:
        a string representation of this grid bag layout.

    - #### getLayoutInfo

          protected GridBagLayoutInfo getLayoutInfo(Container parent,
                                                    int sizeflag)

      Fills in an instance of `GridBagLayoutInfo` for the current set of managed children. This requires three passes through the set of children:
      1. Figure out the dimensions of the layout grid.
      2. Determine which cells the components occupy.
      3. Distribute the weights and min sizes among the rows/columns.
      This also caches the minsizes for all the children when they are first encountered (so subsequent loops don't need to ask again).

      This method should only be used internally by `GridBagLayout`.

      Parameters:
        `parent` - the layout container
        `sizeflag` - either `PREFERREDSIZE` or `MINSIZE`
      Returns:
        the `GridBagLayoutInfo` for the set of children
      Since:
        1.4

    - #### GetLayoutInfo

          protected GridBagLayoutInfo GetLayoutInfo(Container parent,
                                                    int sizeflag)

      This method is obsolete and supplied for backwards compatibility only; new code should call `getLayoutInfo` instead. This method is the same as `getLayoutInfo`; refer to `getLayoutInfo` for details on parameters and return value.

    - #### adjustForGravity

          protected void adjustForGravity(GridBagConstraints constraints,
                                          Rectangle r)

      Adjusts the x, y, width, and height fields to the correct values depending on the constraint geometry and pads. This method should only be used internally by `GridBagLayout`.
      Parameters:
        `constraints` - the constraints to be applied
        `r` - the `Rectangle` to be adjusted
      Since:
        1.4

    - #### AdjustForGravity

          protected void AdjustForGravity(GridBagConstraints constraints,
                                          Rectangle r)

      This method is obsolete and supplied for backwards compatibility only; new code should call `adjustForGravity` instead. This method is the same as `adjustForGravity`; refer to `adjustForGravity` for details on parameters.

    - #### getMinSize

          protected Dimension getMinSize(Container parent,
                                         GridBagLayoutInfo info)

      Figures out the minimum size of the master based on the information from `getLayoutInfo`. This method should only be used internally by `GridBagLayout`.
      Parameters:
        `parent` - the layout container
        `info` - the layout info for this parent
      Returns:
        a `Dimension` object containing the minimum size
      Since:
        1.4

    - #### GetMinSize

          protected Dimension GetMinSize(Container parent,
                                         GridBagLayoutInfo info)

      This method is obsolete and supplied for backwards compatibility only; new code should call `getMinSize` instead. This method is the same as `getMinSize`; refer to `getMinSize` for details on parameters and return value.

    - #### arrangeGrid

          protected void arrangeGrid(Container parent)

      Lays out the grid. This method should only be used internally by `GridBagLayout`.
      Parameters:
        `parent` - the layout container
      Since:
        1.4

    - #### ArrangeGrid

          protected void ArrangeGrid(Container parent)

      This method is obsolete and supplied for backwards compatibility only; new code should call `arrangeGrid` instead. This method is the same as `arrangeGrid`; refer to `arrangeGrid` for details on the parameter.

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