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/OpenJDK 21

Class BasicListUI

java.lang.Object
javax.swing.plaf.ComponentUI
javax.swing.plaf.ListUI
javax.swing.plaf.basic.BasicListUI
Direct Known Subclasses:
SynthListUI
public class BasicListUI extends ListUI
An extensible implementation of ListUI.

BasicListUI instances cannot be shared between multiple lists.

Nested Class Summary

Modifier and Type Class Description
class  BasicListUI.FocusHandler
This class should be treated as a "protected" inner class.
class  BasicListUI.ListDataHandler
The ListDataListener that's added to the JLists model at installUI time, and whenever the JList.model property changes.
class  BasicListUI.ListSelectionHandler
The ListSelectionListener that's added to the JLists selection model at installUI time, and whenever the JList.selectionModel property changes.
class  BasicListUI.MouseInputHandler
Mouse input, and focus handling for JList.
class  BasicListUI.PropertyChangeHandler
The PropertyChangeListener that's added to the JList at installUI time.

Field Summary

Modifier and Type Field Description
protected int cellHeight
The height of cell.
protected int[] cellHeights
The array of cells' height
protected static final int cellRendererChanged
The bit relates to cell renderer changed property.
protected int cellWidth
The width of cell.
protected static final int fixedCellHeightChanged
The bit relates to fixed cell height changed property.
protected static final int fixedCellWidthChanged
The bit relates to fixed cell width changed property.
protected FocusListener focusListener
FocusListener that attached to JList.
protected static final int fontChanged
The bit relates to font changed property.
protected JList<Object> list
The instance of JList.
protected ListDataListener listDataListener
ListDataListener that attached to JList.
protected ListSelectionListener listSelectionListener
ListSelectionListener that attached to JList.
protected static final int modelChanged
The bit relates to model changed property.
protected MouseInputListener mouseInputListener
MouseInputListener that attached to JList.
protected PropertyChangeListener propertyChangeListener
PropertyChangeListener that attached to JList.
protected static final int prototypeCellValueChanged
The bit relates to prototype cell value changed property.
protected CellRendererPane rendererPane
The instance of CellRendererPane.
protected static final int selectionModelChanged
The bit relates to selection model changed property.
protected int updateLayoutStateNeeded
The value represents changes to JList model.

Constructor Summary

Constructor Description
BasicListUI()
Constructs a BasicListUI.

Method Summary

Modifier and Type Method Description
protected int convertRowToY(int row)
Return the JList relative Y coordinate of the origin of the specified row or -1 if row isn't valid.
protected int convertYToRow(int y0)
Convert the JList relative coordinate to the row that contains it, based on the current layout.
protected FocusListener createFocusListener()
Returns an instance of FocusListener.
protected ListDataListener createListDataListener()
Creates an instance of ListDataListener that's added to the JLists by model as needed.
protected ListSelectionListener createListSelectionListener()
Creates an instance of ListSelectionHandler that's added to the JLists by selectionModel as needed.
protected MouseInputListener createMouseInputListener()
Creates a delegate that implements MouseInputListener.
protected PropertyChangeListener createPropertyChangeListener()
Creates an instance of PropertyChangeHandler that's added to the JList by installUI().
static ComponentUI createUI(JComponent list)
Returns a new instance of BasicListUI.
int getBaseline(JComponent c, int width, int height)
Returns the baseline.
Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c)
Returns an enum indicating how the baseline of the component changes as the size changes.
Rectangle getCellBounds(JList<?> list, int index1, int index2)
Returns the bounding rectangle, in the given list's coordinate system, for the range of cells specified by the two indices.
Dimension getPreferredSize(JComponent c)
The preferredSize of the list depends upon the layout orientation.
protected int getRowHeight(int row)
Returns the height of the specified row based on the current layout.
Point indexToLocation(JList<?> list, int index)
Returns the origin in the given JList, of the specified item, in the list's coordinate system.
protected void installDefaults()
Initializes list properties such as font, foreground, and background, and adds the CellRendererPane.
protected void installKeyboardActions()
Registers the keyboard bindings on the JList that the BasicListUI is associated with.
protected void installListeners()
Creates and installs the listeners for the JList, its model, and its selectionModel.
void installUI(JComponent c)
Initializes this.list by calling installDefaults(), installListeners(), and installKeyboardActions() in order.
int locationToIndex(JList<?> list, Point location)
Returns the cell index in the specified JList closest to the given location in the list's coordinate system.
protected void maybeUpdateLayoutState()
If updateLayoutStateNeeded is non zero, call updateLayoutState() and reset updateLayoutStateNeeded.
void paint(Graphics g, JComponent c)
Paint the rows that intersect the Graphics objects clipRect.
protected void paintCell(Graphics g, int row, Rectangle rowBounds, ListCellRenderer<Object> cellRenderer, ListModel<Object> dataModel, ListSelectionModel selModel, int leadIndex)
Paint one List cell: compute the relevant state, get the "rubber stamp" cell renderer component, and then use the CellRendererPane to paint it.
protected void selectNextIndex()
Selected the previous row and force it to be visible.
protected void selectPreviousIndex()
Selected the previous row and force it to be visible.
protected void uninstallDefaults()
Sets the list properties that have not been explicitly overridden to null.
protected void uninstallKeyboardActions()
Unregisters keyboard actions installed from installKeyboardActions.
protected void uninstallListeners()
Removes the listeners from the JList, its model, and its selectionModel.
void uninstallUI(JComponent c)
Uninitializes this.list by calling uninstallListeners(), uninstallKeyboardActions(), and uninstallDefaults() in order.
protected void updateLayoutState()
Recompute the value of cellHeight or cellHeights based and cellWidth, based on the current font and the current values of fixedCellWidth, fixedCellHeight, and prototypeCellValue.

Methods declared in class javax.swing.plaf.ComponentUI

contains, getAccessibleChild, getAccessibleChildrenCount, getMaximumSize, getMinimumSize, update

Methods declared in class java.lang.Object

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

Field Details

list

protected JList<Object> list
The instance of JList.

rendererPane

protected CellRendererPane rendererPane
The instance of CellRendererPane.

focusListener

protected FocusListener focusListener
FocusListener that attached to JList.

mouseInputListener

protected MouseInputListener mouseInputListener
MouseInputListener that attached to JList.

listSelectionListener

protected ListSelectionListener listSelectionListener
ListSelectionListener that attached to JList.

listDataListener

protected ListDataListener listDataListener
ListDataListener that attached to JList.

propertyChangeListener

protected PropertyChangeListener propertyChangeListener
PropertyChangeListener that attached to JList.

cellHeights

protected int[] cellHeights
The array of cells' height

cellHeight

protected int cellHeight
The height of cell.

cellWidth

protected int cellWidth
The width of cell.

updateLayoutStateNeeded

protected int updateLayoutStateNeeded
The value represents changes to JList model.

modelChanged

protected static final int modelChanged
The bit relates to model changed property.
See Also:

selectionModelChanged

protected static final int selectionModelChanged
The bit relates to selection model changed property.
See Also:

fontChanged

protected static final int fontChanged
The bit relates to font changed property.
See Also:

fixedCellWidthChanged

protected static final int fixedCellWidthChanged
The bit relates to fixed cell width changed property.
See Also:

fixedCellHeightChanged

protected static final int fixedCellHeightChanged
The bit relates to fixed cell height changed property.
See Also:

prototypeCellValueChanged

protected static final int prototypeCellValueChanged
The bit relates to prototype cell value changed property.
See Also:

cellRendererChanged

protected static final int cellRendererChanged
The bit relates to cell renderer changed property.
See Also:

Constructor Details

BasicListUI

public BasicListUI()
Constructs a BasicListUI.

Method Details

paintCell

protected void paintCell(Graphics g, int row, Rectangle rowBounds, ListCellRenderer<Object> cellRenderer, ListModel<Object> dataModel, ListSelectionModel selModel, int leadIndex)
Paint one List cell: compute the relevant state, get the "rubber stamp" cell renderer component, and then use the CellRendererPane to paint it. Subclasses may want to override this method rather than paint().
Parameters:
g - an instance of Graphics
row - a row
rowBounds - a bounding rectangle to render to
cellRenderer - a list of ListCellRenderer
dataModel - a list model
selModel - a selection model
leadIndex - a lead index
See Also:

paint

public void paint(Graphics g, JComponent c)
Paint the rows that intersect the Graphics objects clipRect. This method calls paintCell as necessary. Subclasses may want to override these methods.
Overrides:
paint in class ComponentUI
Parameters:
g - the Graphics context in which to paint
c - the component being painted; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components
See Also:

getBaseline

public int getBaseline(JComponent c, int width, int height)
Returns the baseline.
Overrides:
getBaseline in class ComponentUI
Parameters:
c - JComponent baseline is being requested for
width - the width to get the baseline for
height - the height to get the baseline for
Returns:
baseline or a value < 0 indicating there is no reasonable baseline
Throws:
NullPointerException - if c is null
IllegalArgumentException - if width or height is < 0
Since:
1.6
See Also:

getBaselineResizeBehavior

public Component.BaselineResizeBehavior getBaselineResizeBehavior(JComponent c)
Returns an enum indicating how the baseline of the component changes as the size changes.
Overrides:
getBaselineResizeBehavior in class ComponentUI
Parameters:
c - JComponent to return baseline resize behavior for
Returns:
an enum indicating how the baseline changes as the component size changes
Throws:
NullPointerException - if c is null
Since:
1.6
See Also:

getPreferredSize

public Dimension getPreferredSize(JComponent c)
The preferredSize of the list depends upon the layout orientation.
Describes the preferred size for each layout orientation
Layout Orientation Preferred Size
JList.VERTICAL The preferredSize of the list is total height of the rows and the maximum width of the cells. If JList.fixedCellHeight is specified then the total height of the rows is just (cellVerticalMargins + fixedCellHeight) * model.getSize() where rowVerticalMargins is the space we allocate for drawing the yellow focus outline. Similarly if fixedCellWidth is specified then we just use that.
JList.VERTICAL_WRAP If the visible row count is greater than zero, the preferredHeight is the maximum cell height * visibleRowCount. If the visible row count is <= 0, the preferred height is either the current height of the list, or the maximum cell height, whichever is bigger. The preferred width is than the maximum cell width * number of columns needed. Where the number of columns needs is list.height / max cell height. Max cell height is either the fixed cell height, or is determined by iterating through all the cells to find the maximum height from the ListCellRenderer.
JList.HORIZONTAL_WRAP If the visible row count is greater than zero, the preferredHeight is the maximum cell height * adjustedRowCount. Where visibleRowCount is used to determine the number of columns. Because this lays out horizontally the number of rows is then determined from the column count. For example, lets say you have a model with 10 items and the visible row count is 8. The number of columns needed to display this is 2, but you no longer need 8 rows to display this, you only need 5, thus the adjustedRowCount is 5.

If the visible row count is <= 0, the preferred height is dictated by the number of columns, which will be as many as can fit in the width of the JList (width / max cell width), with at least one column. The preferred height then becomes the model size / number of columns * maximum cell height. Max cell height is either the fixed cell height, or is determined by iterating through all the cells to find the maximum height from the ListCellRenderer.

The above specifies the raw preferred width and height. The resulting preferred width is the above width + insets.left + insets.right and the resulting preferred height is the above height + insets.top + insets.bottom. Where the Insets are determined from list.getInsets().
Overrides:
getPreferredSize in class ComponentUI
Parameters:
c - The JList component.
Returns:
The total size of the list.
See Also:

selectPreviousIndex

protected void selectPreviousIndex()
Selected the previous row and force it to be visible.
See Also:

selectNextIndex

protected void selectNextIndex()
Selected the previous row and force it to be visible.
See Also:

installKeyboardActions

protected void installKeyboardActions()
Registers the keyboard bindings on the JList that the BasicListUI is associated with. This method is called at installUI() time.
See Also:

uninstallKeyboardActions

protected void uninstallKeyboardActions()
Unregisters keyboard actions installed from installKeyboardActions. This method is called at uninstallUI() time - subclassess should ensure that all of the keyboard actions registered at installUI time are removed here.
See Also:

installListeners

protected void installListeners()
Creates and installs the listeners for the JList, its model, and its selectionModel. This method is called at installUI() time.
See Also:

uninstallListeners

protected void uninstallListeners()
Removes the listeners from the JList, its model, and its selectionModel. All of the listener fields, are reset to null here. This method is called at uninstallUI() time, it should be kept in sync with installListeners.
See Also:

installDefaults

protected void installDefaults()
Initializes list properties such as font, foreground, and background, and adds the CellRendererPane. The font, foreground, and background properties are only set if their current value is either null or a UIResource, other properties are set if the current value is null.
See Also:

uninstallDefaults

protected void uninstallDefaults()
Sets the list properties that have not been explicitly overridden to null. A property is considered overridden if its current value is not a UIResource.
See Also:

installUI

public void installUI(JComponent c)
Initializes this.list by calling installDefaults(), installListeners(), and installKeyboardActions() in order.
Overrides:
installUI in class ComponentUI
Parameters:
c - the component where this UI delegate is being installed
See Also:

uninstallUI

public void uninstallUI(JComponent c)
Uninitializes this.list by calling uninstallListeners(), uninstallKeyboardActions(), and uninstallDefaults() in order. Sets this.list to null.
Overrides:
uninstallUI in class ComponentUI
Parameters:
c - the component from which this UI delegate is being removed; this argument is often ignored, but might be used if the UI object is stateless and shared by multiple components
See Also:

createUI

public static ComponentUI createUI(JComponent list)
Returns a new instance of BasicListUI. BasicListUI delegates are allocated one per JList.
Parameters:
list - a component
Returns:
a new ListUI implementation for the Windows look and feel.

locationToIndex

public int locationToIndex(JList<?> list, Point location)
Returns the cell index in the specified JList closest to the given location in the list's coordinate system. To determine if the cell actually contains the specified location, compare the point against the cell's bounds, as provided by getCellBounds. This method returns -1 if the list's model is empty.
Specified by:
locationToIndex in class ListUI
Parameters:
list - the list
location - the coordinates of the point
Returns:
the cell index closest to the given location, or -1
Throws:
NullPointerException - if location is null

indexToLocation

public Point indexToLocation(JList<?> list, int index)
Returns the origin in the given JList, of the specified item, in the list's coordinate system. Returns null if the index isn't valid.
Specified by:
indexToLocation in class ListUI
Parameters:
list - the list
index - the cell index
Returns:
the origin of the cell, or null

getCellBounds

public Rectangle getCellBounds(JList<?> list, int index1, int index2)
Returns the bounding rectangle, in the given list's coordinate system, for the range of cells specified by the two indices. The indices can be supplied in any order.

If the smaller index is outside the list's range of cells, this method returns null. If the smaller index is valid, but the larger index is outside the list's range, the bounds of just the first index is returned. Otherwise, the bounds of the valid range is returned.

Specified by:
getCellBounds in class ListUI
Parameters:
list - the list
index1 - the first index in the range
index2 - the second index in the range
Returns:
the bounding rectangle for the range of cells, or null

getRowHeight

protected int getRowHeight(int row)
Returns the height of the specified row based on the current layout.
Parameters:
row - a row
Returns:
the specified row height or -1 if row isn't valid
See Also:

convertYToRow

protected int convertYToRow(int y0)
Convert the JList relative coordinate to the row that contains it, based on the current layout. If y0 doesn't fall within any row, return -1.
Parameters:
y0 - a relative Y coordinate
Returns:
the row that contains y0, or -1
See Also:

convertRowToY

protected int convertRowToY(int row)
Return the JList relative Y coordinate of the origin of the specified row or -1 if row isn't valid.
Parameters:
row - a row
Returns:
the Y coordinate of the origin of row, or -1
See Also:

maybeUpdateLayoutState

protected void maybeUpdateLayoutState()
If updateLayoutStateNeeded is non zero, call updateLayoutState() and reset updateLayoutStateNeeded. This method should be called by methods before doing any computation based on the geometry of the list. For example it's the first call in paint() and getPreferredSize().
See Also:

updateLayoutState

protected void updateLayoutState()
Recompute the value of cellHeight or cellHeights based and cellWidth, based on the current font and the current values of fixedCellWidth, fixedCellHeight, and prototypeCellValue.
See Also:

createMouseInputListener

protected MouseInputListener createMouseInputListener()
Creates a delegate that implements MouseInputListener. The delegate is added to the corresponding java.awt.Component listener lists at installUI() time. Subclasses can override this method to return a custom MouseInputListener, e.g. 
 class MyListUI extends BasicListUI {
    protected MouseInputListener createMouseInputListener() {
        return new MyMouseInputHandler();
    }
    public class MyMouseInputHandler extends MouseInputHandler {
        public void mouseMoved(MouseEvent e) {
            // do some extra work when the mouse moves
            super.mouseMoved(e);
        }
    }
 }
Returns:
an instance of MouseInputListener
See Also:

createFocusListener

protected FocusListener createFocusListener()
Returns an instance of FocusListener.
Returns:
an instance of FocusListener

createListSelectionListener

protected ListSelectionListener createListSelectionListener()
Creates an instance of ListSelectionHandler that's added to the JLists by selectionModel as needed. Subclasses can override this method to return a custom ListSelectionListener, e.g. 
 class MyListUI extends BasicListUI {
    protected ListSelectionListener createListSelectionListener() {
        return new MySelectionListener();
    }
    public class MySelectionListener extends ListSelectionHandler {
        public void valueChanged(ListSelectionEvent e) {
            // do some extra work when the selection changes
            super.valueChange(e);
        }
    }
 }
Returns:
an instance of ListSelectionHandler
See Also:

createListDataListener

protected ListDataListener createListDataListener()
Creates an instance of ListDataListener that's added to the JLists by model as needed. Subclasses can override this method to return a custom ListDataListener, e.g. 
 class MyListUI extends BasicListUI {
    protected ListDataListener createListDataListener() {
        return new MyListDataListener();
    }
    public class MyListDataListener extends ListDataHandler {
        public void contentsChanged(ListDataEvent e) {
            // do some extra work when the models contents change
            super.contentsChange(e);
        }
    }
 }
Returns:
an instance of ListDataListener
See Also:

createPropertyChangeListener

protected PropertyChangeListener createPropertyChangeListener()
Creates an instance of PropertyChangeHandler that's added to the JList by installUI(). Subclasses can override this method to return a custom PropertyChangeListener, e.g. 
 class MyListUI extends BasicListUI {
    protected PropertyChangeListener createPropertyChangeListener() {
        return new MyPropertyChangeListener();
    }
    public class MyPropertyChangeListener extends PropertyChangeHandler {
        public void propertyChange(PropertyChangeEvent e) {
            if (e.getPropertyName().equals("model")) {
                // do some extra work when the model changes
            }
            super.propertyChange(e);
        }
    }
 }
Returns:
an instance of PropertyChangeHandler
See Also:

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https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/javax/swing/plaf/basic/BasicListUI.html