# Class NavigationFilter

java.lang.Object
javax.swing.text.NavigationFilter

public class NavigationFilter extends Object
`NavigationFilter` can be used to restrict where the cursor can be positioned. When the default cursor positioning actions attempt to reposition the cursor they will call into the `NavigationFilter`, assuming the `JTextComponent` has a non-null `NavigationFilter` set. In this manner the `NavigationFilter` can effectively restrict where the cursor can be positioned. Similarly `DefaultCaret` will call into the `NavigationFilter` when the user is changing the selection to further restrict where the cursor can be positioned.

Subclasses can conditionally call into supers implementation to restrict where the cursor can be placed, or call directly into the `FilterBypass`.

Since:
  1.4
See Also:
  - `Caret`
  - `DefaultCaret`
  - `View`

## Nested Class Summary

Nested Classes
Modifier and Type
Class
Description
`static class`
`NavigationFilter.FilterBypass`
Used as a way to circumvent calling back into the caret to position the cursor.

## Constructor Summary

Constructors
Constructor
Description
`NavigationFilter()`
Constructs a `NavigationFilter`.

## Method Summary

Modifier and Type
Method
Description
`int`
`getNextVisualPositionFrom(JTextComponent text, int pos, Position.Bias bias, int direction, Position.Bias[] biasRet)`
Returns the next visual position to place the caret at from an existing position.
`void`
`moveDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)`
Invoked prior to the Caret moving the dot.
`void`
`setDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)`
Invoked prior to the Caret setting the dot.

### Methods declared in class Object

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

## Constructor Details

### NavigationFilter

public NavigationFilter()
Constructs a `NavigationFilter`.

## Method Details

### setDot

public void setDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
Invoked prior to the Caret setting the dot. The default implementation calls directly into the `FilterBypass` with the passed in arguments. Subclasses may wish to conditionally call super with a different location, or invoke the necessary method on the `FilterBypass`

Parameters:
  `fb` - FilterBypass that can be used to mutate caret position
  `dot` - the position >= 0
  `bias` - Bias to place the dot at

### moveDot

public void moveDot(NavigationFilter.FilterBypass fb, int dot, Position.Bias bias)
Invoked prior to the Caret moving the dot. The default implementation calls directly into the `FilterBypass` with the passed in arguments. Subclasses may wish to conditionally call super with a different location, or invoke the necessary methods on the `FilterBypass`.

Parameters:
  `fb` - FilterBypass that can be used to mutate caret position
  `dot` - the position >= 0
  `bias` - Bias for new location

### getNextVisualPositionFrom

public int getNextVisualPositionFrom(JTextComponent text, int pos, Position.Bias bias, int direction, Position.Bias[] biasRet) throws BadLocationException
Returns the next visual position to place the caret at from an existing position. The default implementation simply forwards the method to the root View. Subclasses may wish to further restrict the location based on additional criteria.

Parameters:
  `text` - JTextComponent containing text
  `pos` - Position used in determining next position
  `bias` - Bias used in determining next position
  `direction` - the direction from the current position that can be thought of as the arrow keys typically found on a keyboard. This will be one of the following values:
  - SwingConstants.WEST
  - SwingConstants.EAST
  - SwingConstants.NORTH
  - SwingConstants.SOUTH
  `biasRet` - Used to return resulting Bias of next position
Returns:
  the location within the model that best represents the next location visual position
Throws:
  `BadLocationException` - for a bad location within a document model
  `IllegalArgumentException` - if `direction` doesn't have one of the legal values above