问题
How do I get the indices of the visible rows in a TableView in JavaFX 9? In JavaFX 8, I can do the following:
// --- The offending imports in Java 9
// import com.sun.javafx.scene.control.skin.TableViewSkin;
// import com.sun.javafx.scene.control.skin.VirtualFlow;
/**
* This is a total hack. We need it as scrollTo jumps the selected
* row to the top of the table. Jarring if the row is already
* visible. As a workaround, we only scroll if the row isn't already
* visible
*
* @return A 2 element ray with the start and end index of visible rows
*/
public int[] getVisibleRows() {
TableView<?> tableView = getTableView();
TableViewSkin<?> skin = (TableViewSkin<?>) tableView.getSkin();
if (skin == null) return new int[] {0, 0};
VirtualFlow<?> flow = (VirtualFlow<?>) skin.getChildren().get(1);
int idxFirst;
int idxLast;
if (flow != null &&
flow.getFirstVisibleCellWithinViewPort() != null &&
flow.getLastVisibleCellWithinViewPort() != null) {
idxFirst = flow.getFirstVisibleCellWithinViewPort().getIndex();
if (idxFirst > tableView.getItems().size()) {
idxFirst = tableView.getItems().size() - 1;
}
idxLast = flow.getLastVisibleCellWithinViewPort().getIndex();
if (idxLast > tableView.getItems().size()) {
idxLast = tableView.getItems().size() - 1;
}
}
else {
idxFirst = 0;
idxLast = 0;
}
return new int[]{idxFirst, idxLast};
}
In Java 9, as part of the modularization, the JDK team is hiding the API's that weren't meant to be public (e.g. all packages that start with 'com.sun') If I try to compile this in Java 9, I get errors of:
[...] cannot find symbol
[ERROR] symbol: class TableViewSkin
[ERROR] location: package com.sun.javafx.scene.control.skin
[...] cannot find symbol
[ERROR] symbol: class VirtualFlow
[ERROR] location: package com.sun.javafx.scene.control.skin
Is there any official way to get the visible rows in a TableView? Any ideas on another, better workaround for this?
UPDATED: Solution based on @user4712734's solution
TableViewExt<?> tableViewExt = new TableViewExt<>(tableView);
public int[] getVisibleRows() {
return new int[]{ tableViewExt.getFirstVisibleIndex(),
tableViewExt.getLastVisibleIndex()};
}
Code for TableViewExt
回答1:
I had same issue as I was also using the JavaFX 8 specific TableViewSkin/VirtualFlow code, but now use this workaround which wraps up some of the suggestions in another post on this issue - see Tableview visible rows
This workaround runs and compiles in Java8/9 and does not use reference package com.sun.javafx. To use the class you need to create a TableViewExtra between constructing your TableView and adding rows to it:
TableView<YourRowType> tableView = new TableView<YourRowType>();
TableViewExtra<YourRowType> tvX = new TableViewExtra(tableView);
// Add some rows etc
Then you can call:
int firstVisRowIndex = tvX.getFirstVisibleIndex();
int lastVisRowIndex = tvX.getLastVisibleIndex();
txV.scrollToSelection();
You can see the old com.sun.javafx dependencies I once used in comments:
import java.util.LinkedHashSet;
//com.sun.javafx: START
//import com.sun.javafx.scene.control.skin.TableViewSkin;
//import com.sun.javafx.scene.control.skin.VirtualFlow;
//import javafx.beans.value.ChangeListener;
//import javafx.beans.value.ObservableValue;
//import javafx.scene.Node;
//import javafx.scene.control.IndexedCell;
//import javafx.scene.control.Skin;
// com.sun.javafx: END
import javafx.collections.ObservableList;
import javafx.scene.control.TableRow;
import javafx.scene.control.TableView;
import javafx.util.Callback;
/**
* Extra calls for TableView which would have been nice to see in JavaFx TableView
*/
public class TableViewExtra<T> // com.sun.javafx: implements ChangeListener<Skin<?>>
{
private final TableView<T> tableView;
// com.sun.javafx: private VirtualFlow<?> flow;
LinkedHashSet<TableRow<T>> rows = new LinkedHashSet<>();
private int firstIndex;
private int lastIndex;
public TableViewExtra(TableView<T> tableView)
{
this.tableView = tableView;
// com.sun.javafx: tableView.skinProperty().addListener(this);
// Callback to monitor row creation and to identify visible screen rows
final Callback<TableView<T>, TableRow<T>> rf = tableView.getRowFactory();
final Callback<TableView<T>, TableRow<T>> modifiedRowFactory = new Callback<TableView<T>, TableRow<T>>() {
@Override
public TableRow<T> call(TableView<T> param)
{
TableRow<T> r = rf != null ? rf.call(param) : new TableRow<T>();
// Save row, this implementation relies on JaxaFX re-using TableRow efficiently
rows.add(r);
return r;
}
};
tableView.setRowFactory(modifiedRowFactory);
}
// com.sun.javafx BEGIN
// public void changed(ObservableValue<? extends Skin<?>> ov, Skin<?> t, Skin<?> t1)
// {
// if (t1 == null) {
// return;
// }
//
// TableViewSkin<?> tvs = (TableViewSkin<?>) t1;
// ObservableList<Node> kids = tvs.getChildren();
//
// if (kids == null || kids.isEmpty() || kids.size() < 2) {
// return;
// }
// flow = (VirtualFlow<?>) kids.get(1);
// }
// com.sun.javafx END
/**
* Changes the current view to ensure that one of the passed index positions
* is visible on screen. The view is not changed if any of the passed index positions is already visible.
* The table scroll position is moved so that the closest index to the current position is visible.
* @param indices Assumed to be in ascending order.
*
*/
public void
scrollToIndex(int ... indices)
{
int first = getFirstVisibleIndex();
int last = getLastVisibleIndex();
int where = first;
boolean changeScrollPos = true;
// No point moving current scroll position if one of the index items is visible already:
if (first >= 0 && last >= first)
for (int idx : indices)
{
if (first <= idx && idx <= last)
{
changeScrollPos = false;
break;
}
}
if (indices.length > 0 && changeScrollPos)
{
where = indices[0];
if (first >= 0)
{
int x = closestTo(indices, first);
int abs = Math.abs(x - first);
if (abs < Math.abs(where - first))
{
where = x;
}
}
if (last >= 0)
{
int x = closestTo(indices, last);
int abs = Math.abs(x - last);
if (abs < Math.abs(where - last))
{
where = x;
}
}
tableView.scrollTo(where);
}
}
private static int closestTo(int[] indices, int value)
{
int x = indices[0];
int diff = Math.abs(value - x);
int newDiff = diff;
for (int v : indices)
{
newDiff = Math.abs(value - v);
if (newDiff < diff)
{
x = v;
diff = newDiff;
}
}
return x;
}
private void recomputeVisibleIndexes()
{
firstIndex = -1;
lastIndex = -1;
// Work out which of the rows are visible
double tblViewHeight = tableView.getHeight();
double headerHeight = tableView.lookup(".column-header-background").getBoundsInLocal().getHeight();
double viewPortHeight = tblViewHeight - headerHeight;
for(TableRow<T> r : rows)
{
if (!r.isVisible()) continue; // tingyik90
double minY = r.getBoundsInParent().getMinY();
double maxY = r.getBoundsInParent().getMaxY();
boolean hidden = (maxY < 0) || (minY > viewPortHeight);
// boolean fullyVisible = !hidden && (maxY <= viewPortHeight) && (minY >= 0);
if (!hidden)
{
if (firstIndex < 0 || r.getIndex() < firstIndex)
{
firstIndex = r.getIndex();
}
if (lastIndex < 0 || r.getIndex() > lastIndex)
{
lastIndex = r.getIndex();
}
}
}
}
/**
* Find the first row in the tableView which is visible on the display
* @return -1 if none visible or the index of the first visible row (wholly or fully)
*/
public int getFirstVisibleIndex()
{
// com.sun.javafx: START
// int jre8Index = -1;
// if (flow != null)
// {
// IndexedCell<?> cell = flow.getFirstVisibleCell();
// if (cell != null)
// {
// jre8Index = cell.getIndex();
// }
// }
// com.sun.javafx: END
recomputeVisibleIndexes();
System.out.println("getFirstVisibleIndex "+firstIndex+" rows="+rows.size()/*com.sun.javafx:+" jre8Index="+jre8Index*/);
return firstIndex;
}
/**
* Find the last row in the tableView which is visible on the display
* @return -1 if none visible or the index of the last visible row (wholly or fully)
*/
public int getLastVisibleIndex()
{
// com.sun.javafx: END
// int jre8Index = -1;
// if (flow != null)
// {
// IndexedCell<?> cell = flow.getLastVisibleCell();
// if (cell != null)
// jre8Index = cell.getIndex();
// }
// com.sun.javafx: END
recomputeVisibleIndexes();
System.out.println("getLastVisibleIndex "+lastIndex+" rows="+rows.size()/*com.sun.javafx:+" jre8Index="+jre8Index*/);
return lastIndex;
}
/**
* Ensure that some part of the current selection is visible in the display view
*/
public void scrollToSelection()
{
ObservableList<Integer> seln = tableView.getSelectionModel().getSelectedIndices();
int[] indices = new int[seln.size()];
for (int i = 0; i < indices.length; i++)
{
indices[i] = seln.get(i).intValue();
}
scrollToIndex(indices);
}
}
回答2:
You shall probably migrate to using the module javafx.controls which has been introduced since Java9:-
module your.module {
requires javafx.controls;
}
which exports the javafx.scene.control and javafx.scene.control.skin packages as required by the classes in use in your code.
module javafx.controls {
...
exports javafx.scene.control.skin;
exports javafx.scene.control;
...
}
来源：https://stackoverflow.com/questions/46474385/how-to-find-the-indices-of-the-visible-rows-in-a-tableview-in-javafx-9