DefaultRowSorter (Java SE 26 & JDK 26)
Description: declaration: module: java.desktop, package: javax.swing, class: DefaultRowSorter
Keywords: javax.swing.DefaultRowSorter class

# Class DefaultRowSorter<M,I>

java.lang.Object
javax.swing.RowSorter<M>
javax.swing.DefaultRowSorter<M,I>

Type Parameters:
  `M` - the type of the model
  `I` - the type of the identifier passed to the `RowFilter`

Direct Known Subclasses:
  `TableRowSorter`

public abstract class DefaultRowSorter<M,I> extends RowSorter<M>
An implementation of `RowSorter` that provides sorting and filtering around a grid-based data model. Beyond creating and installing a `RowSorter`, you very rarely need to interact with one directly. Refer to `TableRowSorter` for a concrete implementation of `RowSorter` for `JTable`.

Sorting is done based on the current `SortKey`s, in order. If two objects are equal (the `Comparator` for the column returns 0) the next `SortKey` is used. If no `SortKey`s remain or the order is `UNSORTED`, then the order of the rows in the model is used.

Sorting of each column is done by way of a `Comparator` that you can specify using the `setComparator` method. If a `Comparator` has not been specified, the `Comparator` returned by `Collator.getInstance()` is used on the results of calling `toString` on the underlying objects. The `Comparator` is never passed `null`. A `null` value is treated as occurring before a non-`null` value, and two `null` values are considered equal.

If you specify a `Comparator` that casts its argument to a type other than that provided by the model, a `ClassCastException` will be thrown when the data is sorted.

In addition to sorting, `DefaultRowSorter` provides the ability to filter rows. Filtering is done by way of a `RowFilter` that is specified using the `setRowFilter` method. If no filter has been specified all rows are included.

By default, rows are in unsorted order (the same as the model) and every column is sortable. The default `Comparator`s are documented in the subclasses (for example, `TableRowSorter`).

If the underlying model structure changes (the `modelStructureChanged` method is invoked) the following are reset to their default values: `Comparator`s by column, current sort order, and whether each column is sortable. To find the default `Comparator`s, see the concrete implementation (for example, `TableRowSorter`). The default sort order is unsorted (the same as the model), and columns are sortable by default.

`DefaultRowSorter` is an abstract class. Concrete subclasses must provide access to the underlying data by invoking `setModelWrapper`. The `setModelWrapper` method must be invoked soon after the constructor is called, ideally from within the subclass's constructor. Undefined behavior will result if you use a `DefaultRowSorter` without specifying a `ModelWrapper`.

`DefaultRowSorter` has two formal type parameters. The first type parameter corresponds to the class of the model, for example `DefaultTableModel`. The second type parameter corresponds to the class of the identifier passed to the `RowFilter`. Refer to `TableRowSorter` and `RowFilter` for more details on the type parameters.

Since:
  1.6
See Also:
  - `TableRowSorter`
  - `DefaultTableModel`
  - `Collator`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `protected static class`
  `DefaultRowSorter.ModelWrapper<M,I>`
  `DefaultRowSorter.ModelWrapper` is responsible for providing the data that gets sorted by `DefaultRowSorter`.

  ### Nested classes/interfaces declared in class RowSorter

  `RowSorter.SortKey`
  Modifier and Type
  Class
  Description
  `static class`
  `RowSorter.SortKey`
  SortKey describes the sort order for a particular column.

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `DefaultRowSorter()`
  Creates an empty `DefaultRowSorter`.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `allRowsChanged()`
  Invoked when the contents of the underlying model have completely changed.
  `int`
  `convertRowIndexToModel(int index)`
  Returns the location of `index` in terms of the underlying model.
  `int`
  `convertRowIndexToView(int index)`
  Returns the location of `index` in terms of the view.
  `Comparator<?>`
  `getComparator(int column)`
  Returns the `Comparator` for the specified column.
  `int`
  `getMaxSortKeys()`
  Returns the maximum number of sort keys.
  `final M`
  `getModel()`
  Returns the underlying model.
  `int`
  `getModelRowCount()`
  Returns the number of rows in the underlying model.
  `protected final DefaultRowSorter.ModelWrapper<M,I>`
  `getModelWrapper()`
  Returns the model wrapper providing the data that is being sorted and filtered.
  `RowFilter<? super M, ? super I>`
  `getRowFilter()`
  Returns the filter that determines which rows, if any, should be hidden from view.
  `List<? extends RowSorter.SortKey>`
  `getSortKeys()`
  Returns the current sort keys.
  `boolean`
  `getSortsOnUpdates()`
  Returns true if a sort should happen when the underlying model is updated; otherwise, returns false.
  `int`
  `getViewRowCount()`
  Returns the number of rows in the view.
  `boolean`
  `isSortable(int column)`
  Returns true if the specified column is sortable; otherwise, false.
  `void`
  `modelStructureChanged()`
  Invoked when the underlying model structure has completely changed.
  `void`
  `rowsDeleted(int firstRow, int endRow)`
  Invoked when rows have been deleted from the underlying model in the specified range (inclusive).
  `void`
  `rowsInserted(int firstRow, int endRow)`
  Invoked when rows have been inserted into the underlying model in the specified range (inclusive).
  `void`
  `rowsUpdated(int firstRow, int endRow)`
  Invoked when rows have been changed in the underlying model between the specified range (inclusive).
  `void`
  `rowsUpdated(int firstRow, int endRow, int column)`
  Invoked when the column in the rows have been updated in the underlying model between the specified range.
  `void`
  `setComparator(int column, Comparator<?> comparator)`
  Sets the `Comparator` to use when sorting the specified column.
  `void`
  `setMaxSortKeys(int max)`
  Sets the maximum number of sort keys.
  `protected final void`
  `setModelWrapper(DefaultRowSorter.ModelWrapper<M,I> modelWrapper)`
  Sets the model wrapper providing the data that is being sorted and filtered.
  `void`
  `setRowFilter(RowFilter<? super M, ? super I> filter)`
  Sets the filter that determines which rows, if any, should be hidden from the view.
  `void`
  `setSortable(int column, boolean sortable)`
  Sets whether or not the specified column is sortable.
  `void`
  `setSortKeys(List<? extends RowSorter.SortKey> sortKeys)`
  Sets the sort keys.
  `void`
  `setSortsOnUpdates(boolean sortsOnUpdates)`
  If true, specifies that a sort should happen when the underlying model is updated (`rowsUpdated` is invoked).
  `void`
  `sort()`
  Sorts and filters the rows in the view based on the sort keys of the columns currently being sorted and the filter, if any, associated with this sorter.
  `void`
  `toggleSortOrder(int column)`
  Reverses the sort order from ascending to descending (or descending to ascending) if the specified column is already the primary sorted column; otherwise, makes the specified column the primary sorted column, with an ascending sort order.
  `protected boolean`
  `useToString(int column)`
  Returns whether or not to convert the value to a string before doing comparisons when sorting.

  ### Methods declared in class RowSorter

  `addRowSorterListener, fireRowSorterChanged, fireSortOrderChanged, removeRowSorterListener`
  Modifier and Type
  Method
  Description
  `void`
  `addRowSorterListener(RowSorterListener l)`
  Adds a `RowSorterListener` to receive notification about this `RowSorter`.
  `protected void`
  `fireRowSorterChanged(int[] lastRowIndexToModel)`
  Notifies listener that the mapping has changed.
  `protected void`
  `fireSortOrderChanged()`
  Notifies listener that the sort order has changed.
  `void`
  `removeRowSorterListener(RowSorterListener l)`
  Removes a `RowSorterListener`.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`
  Modifier and Type
  Method
  Description
  `protected Object`
  `clone()`
  Creates and returns a copy of this object.
  `boolean`
  `equals(Object obj)`
  Indicates whether some other object is "equal to" this one.
  `protected void`
  `finalize()`
  Deprecated, for removal: This API element is subject to removal in a future version.
  Finalization is deprecated and subject to removal in a future release.
  `final Class<?>`
  `getClass()`
  Returns the runtime class of this `Object`.
  `int`
  `hashCode()`
  Returns a hash code value for this object.
  `final void`
  `notify()`
  Wakes up a single thread that is waiting on this object's monitor.
  `final void`
  `notifyAll()`
  Wakes up all threads that are waiting on this object's monitor.
  `String`
  `toString()`
  Returns a string representation of the object.
  `final void`
  `wait()`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
  `final void`
  `wait(long timeoutMillis)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
  `final void`
  `wait(long timeoutMillis, int nanos)`
  Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

- ## Constructor Details

  - ### DefaultRowSorter

    public DefaultRowSorter()
    Creates an empty `DefaultRowSorter`.

- ## Method Details

  - ### setModelWrapper

    protected final void setModelWrapper(DefaultRowSorter.ModelWrapper<M,I> modelWrapper)
    Sets the model wrapper providing the data that is being sorted and filtered.
    Parameters:
      `modelWrapper` - the model wrapper responsible for providing the data that gets sorted and filtered
    Throws:
      `IllegalArgumentException` - if `modelWrapper` is `null`

  - ### getModelWrapper

    protected final DefaultRowSorter.ModelWrapper<M,I> getModelWrapper()
    Returns the model wrapper providing the data that is being sorted and filtered.
    Returns:
      the model wrapper responsible for providing the data that gets sorted and filtered

  - ### getModel

    public final M getModel()
    Returns the underlying model.
    Specified by:
      `getModel` in class `RowSorter<M>`
    Returns:
      the underlying model

  - ### setSortable

    public void setSortable(int column, boolean sortable)
    Sets whether or not the specified column is sortable. The specified value is only checked when `toggleSortOrder` is invoked. It is still possible to sort on a column that has been marked as unsortable by directly setting the sort keys. The default is true.
    Parameters:
      `column` - the column to enable or disable sorting on, in terms of the underlying model
      `sortable` - whether or not the specified column is sortable
    Throws:
      `IndexOutOfBoundsException` - if `column` is outside the range of the model
    See Also:
      - `toggleSortOrder(int)`
      - `setSortKeys(List)`

  - ### isSortable

    public boolean isSortable(int column)
    Returns true if the specified column is sortable; otherwise, false.
    Parameters:
      `column` - the column to check sorting for, in terms of the underlying model
    Returns:
      true if the column is sortable
    Throws:
      `IndexOutOfBoundsException` - if column is outside the range of the underlying model

  - ### setSortKeys

    public void setSortKeys(List<? extends RowSorter.SortKey> sortKeys)
    Sets the sort keys. This creates a copy of the supplied `List`; subsequent changes to the supplied `List` do not effect this `DefaultRowSorter`. If the sort keys have changed this triggers a sort.
    Specified by:
      `setSortKeys` in class `RowSorter<M>`
    Parameters:
      `sortKeys` - the new `SortKeys`; `null` is a shorthand for specifying an empty list, indicating that the view should be unsorted
    Throws:
      `IllegalArgumentException` - if any of the values in `sortKeys` are null or have a column index outside the range of the model

  - ### getSortKeys

    public List<? extends RowSorter.SortKey> getSortKeys()
    Returns the current sort keys. This returns an unmodifiable `non-null List`. If you need to change the sort keys, make a copy of the returned `List`, mutate the copy and invoke `setSortKeys` with the new list.
    Specified by:
      `getSortKeys` in class `RowSorter<M>`
    Returns:
      the current sort order

  - ### setMaxSortKeys

    public void setMaxSortKeys(int max)
    Sets the maximum number of sort keys. The number of sort keys determines how equal values are resolved when sorting. For example, assume a table row sorter is created and `setMaxSortKeys(2)` is invoked on it. The user clicks the header for column 1, causing the table rows to be sorted based on the items in column 1. Next, the user clicks the header for column 2, causing the table to be sorted based on the items in column 2; if any items in column 2 are equal, then those particular rows are ordered based on the items in column 1. In this case, we say that the rows are primarily sorted on column 2, and secondarily on column 1. If the user then clicks the header for column 3, then the items are primarily sorted on column 3 and secondarily sorted on column 2. Because the maximum number of sort keys has been set to 2 with `setMaxSortKeys`, column 1 no longer has an effect on the order.

    The maximum number of sort keys is enforced by `toggleSortOrder`. You can specify more sort keys by invoking `setSortKeys` directly and they will all be honored. However if `toggleSortOrder` is subsequently invoked the maximum number of sort keys will be enforced. The default value is 3.

    Parameters:
      `max` - the maximum number of sort keys
    Throws:
      `IllegalArgumentException` - if `max` < 1

  - ### getMaxSortKeys

    public int getMaxSortKeys()
    Returns the maximum number of sort keys.
    Returns:
      the maximum number of sort keys

  - ### setSortsOnUpdates

    public void setSortsOnUpdates(boolean sortsOnUpdates)
    If true, specifies that a sort should happen when the underlying model is updated (`rowsUpdated` is invoked). For example, if this is true and the user edits an entry the location of that item in the view may change. The default is false.
    Parameters:
      `sortsOnUpdates` - whether or not to sort on update events

  - ### getSortsOnUpdates

    public boolean getSortsOnUpdates()
    Returns true if a sort should happen when the underlying model is updated; otherwise, returns false.
    Returns:
      whether or not to sort when the model is updated

  - ### setRowFilter

    public void setRowFilter(RowFilter<? super M, ? super I> filter)
    Sets the filter that determines which rows, if any, should be hidden from the view. The filter is applied before sorting. A value of `null` indicates all values from the model should be included.

    `RowFilter`'s `include` method is passed an `Entry` that wraps the underlying model. The number of columns in the `Entry` corresponds to the number of columns in the `ModelWrapper`. The identifier comes from the `ModelWrapper` as well.

    This method triggers a sort.

    Parameters:
      `filter` - the filter used to determine what entries should be included

  - ### getRowFilter

    public RowFilter<? super M, ? super I> getRowFilter()
    Returns the filter that determines which rows, if any, should be hidden from view.
    Returns:
      the filter

  - ### toggleSortOrder

    public void toggleSortOrder(int column)
    Reverses the sort order from ascending to descending (or descending to ascending) if the specified column is already the primary sorted column; otherwise, makes the specified column the primary sorted column, with an ascending sort order. If the specified column is not sortable, this method has no effect.
    Specified by:
      `toggleSortOrder` in class `RowSorter<M>`
    Parameters:
      `column` - index of the column to make the primary sorted column, in terms of the underlying model
    Throws:
      `IndexOutOfBoundsException` - if column is outside the range of the underlying model
    See Also:
      - `setSortable(int,boolean)`
      - `setMaxSortKeys(int)`

  - ### convertRowIndexToView

    public int convertRowIndexToView(int index)
    Returns the location of `index` in terms of the view. That is, for the row `index` in the coordinates of the underlying model this returns the row index in terms of the view.
    Specified by:
      `convertRowIndexToView` in class `RowSorter<M>`
    Parameters:
      `index` - the row index in terms of the underlying model
    Returns:
      row index in terms of the view, or -1 if index has been filtered out of the view
    Throws:
      `IndexOutOfBoundsException` - if `index` is outside the range of the model

  - ### convertRowIndexToModel

    public int convertRowIndexToModel(int index)
    Returns the location of `index` in terms of the underlying model. That is, for the row `index` in the coordinates of the view this returns the row index in terms of the underlying model.
    Specified by:
      `convertRowIndexToModel` in class `RowSorter<M>`
    Parameters:
      `index` - the row index in terms of the underlying view
    Returns:
      row index in terms of the view
    Throws:
      `IndexOutOfBoundsException` - if `index` is outside the range of the view

  - ### sort

    public void sort()
    Sorts and filters the rows in the view based on the sort keys of the columns currently being sorted and the filter, if any, associated with this sorter. An empty `sortKeys` list indicates that the view should unsorted, the same as the model.
    See Also:
      - `setRowFilter(RowFilter)`
      - `setSortKeys(List)`

  - ### useToString

    protected boolean useToString(int column)
    Returns whether or not to convert the value to a string before doing comparisons when sorting. If true `ModelWrapper.getStringValueAt` will be used, otherwise `ModelWrapper.getValueAt` will be used. It is up to subclasses, such as `TableRowSorter`, to honor this value in their `ModelWrapper` implementation.
    Parameters:
      `column` - the index of the column to test, in terms of the underlying model
    Returns:
      true if values are to be converted to strings before doing comparisons when sorting
    Throws:
      `IndexOutOfBoundsException` - if `column` is not valid

  - ### setComparator

    public void setComparator(int column, Comparator<?> comparator)
    Sets the `Comparator` to use when sorting the specified column. This does not trigger a sort. If you want to sort after setting the comparator you need to explicitly invoke `sort`.
    Parameters:
      `column` - the index of the column the `Comparator` is to be used for, in terms of the underlying model
      `comparator` - the `Comparator` to use
    Throws:
      `IndexOutOfBoundsException` - if `column` is outside the range of the underlying model

  - ### getComparator

    public Comparator<?> getComparator(int column)
    Returns the `Comparator` for the specified column. This will return `null` if a `Comparator` has not been specified for the column.
    Parameters:
      `column` - the column to fetch the `Comparator` for, in terms of the underlying model
    Returns:
      the `Comparator` for the specified column
    Throws:
      `IndexOutOfBoundsException` - if column is outside the range of the underlying model

  - ### getViewRowCount

    public int getViewRowCount()
    Returns the number of rows in the view. If the contents have been filtered this might differ from the row count of the underlying model.
    Specified by:
      `getViewRowCount` in class `RowSorter<M>`
    Returns:
      number of rows in the view
    See Also:
      - `RowSorter.getModelRowCount()`

  - ### getModelRowCount

    public int getModelRowCount()
    Returns the number of rows in the underlying model.
    Specified by:
      `getModelRowCount` in class `RowSorter<M>`
    Returns:
      number of rows in the underlying model
    See Also:
      - `RowSorter.getViewRowCount()`

  - ### modelStructureChanged

    public void modelStructureChanged()
    Invoked when the underlying model structure has completely changed. For example, if the number of columns in a `TableModel` changed, this method would be invoked.

    You normally do not call this method. This method is public to allow view classes to call it.

    Specified by:
      `modelStructureChanged` in class `RowSorter<M>`

  - ### allRowsChanged

    public void allRowsChanged()
    Invoked when the contents of the underlying model have completely changed. The structure of the table is the same, only the contents have changed. This is typically sent when it is too expensive to characterize the change in terms of the other methods.

    You normally do not call this method. This method is public to allow view classes to call it.

    Specified by:
      `allRowsChanged` in class `RowSorter<M>`

  - ### rowsInserted

    public void rowsInserted(int firstRow, int endRow)
    Invoked when rows have been inserted into the underlying model in the specified range (inclusive).

    The arguments give the indices of the effected range. The first argument is in terms of the model before the change, and must be less than or equal to the size of the model before the change. The second argument is in terms of the model after the change and must be less than the size of the model after the change. For example, if you have a 5-row model and add 3 items to the end of the model the indices are 5, 7.

    You normally do not call this method. This method is public to allow view classes to call it.

    Specified by:
      `rowsInserted` in class `RowSorter<M>`
    Parameters:
      `firstRow` - the first row
      `endRow` - the last row
    Throws:
      `IndexOutOfBoundsException` - if either argument is invalid, or `firstRow` > `endRow`

  - ### rowsDeleted

    public void rowsDeleted(int firstRow, int endRow)
    Invoked when rows have been deleted from the underlying model in the specified range (inclusive).

    The arguments give the indices of the effected range and are in terms of the model before the change. For example, if you have a 5-row model and delete 3 items from the end of the model the indices are 2, 4.

    You normally do not call this method. This method is public to allow view classes to call it.

    Specified by:
      `rowsDeleted` in class `RowSorter<M>`
    Parameters:
      `firstRow` - the first row
      `endRow` - the last row
    Throws:
      `IndexOutOfBoundsException` - if either argument is outside the range of the model before the change, or `firstRow` > `endRow`

  - ### rowsUpdated

    public void rowsUpdated(int firstRow, int endRow)
    Invoked when rows have been changed in the underlying model between the specified range (inclusive).

    You normally do not call this method. This method is public to allow view classes to call it.

    Specified by:
      `rowsUpdated` in class `RowSorter<M>`
    Parameters:
      `firstRow` - the first row, in terms of the underlying model
      `endRow` - the last row, in terms of the underlying model
    Throws:
      `IndexOutOfBoundsException` - if either argument is outside the range of the underlying model, or `firstRow` > `endRow`

  - ### rowsUpdated

    public void rowsUpdated(int firstRow, int endRow, int column)
    Invoked when the column in the rows have been updated in the underlying model between the specified range.

    You normally do not call this method. This method is public to allow view classes to call it.

    Specified by:
      `rowsUpdated` in class `RowSorter<M>`
    Parameters:
      `firstRow` - the first row, in terms of the underlying model
      `endRow` - the last row, in terms of the underlying model
      `column` - the column that has changed, in terms of the underlying model
    Throws:
      `IndexOutOfBoundsException` - if either argument is outside the range of the underlying model after the change, `firstRow` > `endRow`, or `column` is outside the range of the underlying model