java - 对整个列表进行分页 TableView 排序时出错
问题描述
我正在尝试实现一个分页表视图，它允许按 JavaFX 中的所有项目进行排序。我从这里实现了分页表视图：https ://stackoverflow.com/a/25424208/12181863 。由jewelsea 和tim buthe 提供。
我在想，因为表视图只访问项目的子列表，所以我想根据我对 Java 文档排序部分的理解，将排序从表列扩展到完整列表：https://docs .oracle.com/javase/8/javafx/api/javafx/scene/control/TableView.html#setItems-javafx.collections.ObservableList-
// bind the sortedList comparator to the TableView comparator
//i m guessing it extends the sorting from the table to the actual list?
sortedList.comparatorProperty().bind(tableView.comparatorProperty());
然后刷新相同子列表索引的表视图（由于整个列表已排序，因此现在应该对其进行排序）。
基本上，我想使用表格列比较器对完整列表进行排序，然后使用新的排序列表“刷新”表格视图。这可行吗？或者有没有更简单的方法来解决这个问题？
我还参考了其他参考资料，例如：https ://incepttechnologies.blogspot.com/p/javafx-tableview-with-pagination-and.html但我发现很难理解，因为一切都在解释模糊的地方.
快速提取我的 TouchDisplayEmulatorController 类中的核心组件
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Pagination;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.util.Callback;
import java.util.ArrayList;
import java.util.List;
public class TouchDisplayEmulatorController extends Application {
public TableView sensorsTable;
public List<Sensor> sensors;
public int rowsPerPage = 14;
public GridPane grids = new GridPane();
public long timenow;
public void start(final Stage stage) throws Exception {
grids = new GridPane();
setGridPane();
Scene scene = new Scene(grids, 1024, 768);
stage.setScene(scene);
stage.setTitle("Table pager");
stage.show();
}
//public static void main(String[] args) throws Exception {
// launch(args);
//}
public void setGridPane(){
processSensors();
sensorsGrid();
}
public void sensorsGrid(){
buildTable();
int numOfPages = 1;
if (sensors.size() % rowsPerPage == 0) {
numOfPages = sensors.size() / rowsPerPage;
} else if (sensors.size() > rowsPerPage) {
numOfPages = sensors.size() / rowsPerPage + 1;
}
Pagination pagination = new Pagination((numOfPages), 0);
pagination.setPageFactory(this::createPage);
pagination.setMaxPageIndicatorCount(numOfPages);
grids.add(pagination, 0, 0);
}
private Node createPage(int pageIndex) {
int fromIndex = pageIndex * rowsPerPage;
int toIndex = Math.min(fromIndex + rowsPerPage, sensors.size());
sensorsTable.setItems(FXCollections.observableArrayList(sensors.subList(fromIndex, toIndex)));
return new BorderPane(sensorsTable);
}
public void processSensors(){
sensors = new ArrayList<>();
// long timenow = OffsetDateTime.now(ZoneOffset.UTC).toInstant().toEpochMilli()/1000;
// StringTokenizer hildetoken = new StringTokenizer(msg);
for (int i=0; i<20; i++) {
sensors.add(new Sensor(String.valueOf(i), "rid-"+i, "sid-"+i, "0", "0", "no condition"));
}
}
public void buildTable() {
sensorsTable = new TableView();
TableColumn<Sensor, String> userid = new TableColumn<>("userid");
userid.setCellValueFactory(param -> param.getValue().userid);
userid.setPrefWidth(100);
TableColumn<Sensor, String> resourceid = new TableColumn<>("resourceid");
resourceid.setCellValueFactory(param -> param.getValue().resourceid);
resourceid.setPrefWidth(100);
TableColumn<Sensor, String> column1 = new TableColumn<>("sid");
column1.setCellValueFactory(param -> param.getValue().sid);
column1.setPrefWidth(100);
TableColumn<Sensor, String> column2 = new TableColumn<>("timestamp");
column2.setCellValueFactory(param -> param.getValue().timestamp);
column2.setPrefWidth(100);
TableColumn<Sensor, String> column3 = new TableColumn<>("reading");
column3.setCellValueFactory(param -> param.getValue().reading);
column3.setPrefWidth(100);
TableColumn<Sensor, String> column4 = new TableColumn<>("last contacted");
column4.setCellFactory(new Callback<TableColumn<Sensor, String>, TableCell<Sensor, String>>() {
@Override
public TableCell<Sensor, String> call(TableColumn<Sensor, String> sensorStringTableColumn) {
return new TableCell<Sensor, String>() {
public void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
if (!isEmpty()) {
this.setTextFill(Color.WHITE);
if (item.contains("@")) {
this.setTextFill(Color.BLUEVIOLET);
} else if (item.equals("> 8 hour ago")) {
this.setStyle("-fx-background-color: red;");
} else if (item.equals("< 8 hour ago")) {
this.setStyle("-fx-background-color: orange;");
//this.setTextFill(Color.ORANGE);
} else if (item.equals("< 4 hour ago")) {
this.setStyle("-fx-background-color: yellow;");
this.setTextFill(Color.BLACK);
} else if (item.equals("< 1 hour ago")) {
this.setStyle("-fx-background-color: green;");
//this.setTextFill(Color.GREEN);
}
setText(item);
}
}
};
}
});
column4.setCellValueFactory(param -> param.getValue().condition);
column4.setPrefWidth(100);
sensorsTable.getColumns().addAll(userid, resourceid, column1, column2, column3, column4);
}
}
class Sensor {
public SimpleStringProperty userid;
public SimpleStringProperty resourceid;
public SimpleStringProperty sid;
public SimpleStringProperty timestamp;
public SimpleStringProperty reading;
public SimpleStringProperty condition;
public Sensor(String userid, String resourceid, String sid, String timestamp, String reading, String condition){
this.userid = new SimpleStringProperty(userid);
this.resourceid = new SimpleStringProperty(resourceid);
this.sid = new SimpleStringProperty(sid);
this.timestamp = new SimpleStringProperty(timestamp);
this.reading = new SimpleStringProperty(reading);
this.condition = new SimpleStringProperty(condition);
//we can use empty string or condition 3 here
}
public Sensor(String sid, String timestamp, String reading, String condition){
this.userid = new SimpleStringProperty("-1");
this.resourceid = new SimpleStringProperty("-1");
this.sid = new SimpleStringProperty(sid);
this.timestamp= new SimpleStringProperty(timestamp);
this.reading= new SimpleStringProperty(reading);
this.condition = new SimpleStringProperty(condition);
}
public String getUserid() { return this.userid.toString(); }
public String getResourceid() { return this.resourceid.toString(); }
public String getSid() { return this.sid.toString(); }
public String getTimestamp() { return this.timestamp.toString(); }
public String getReading() { return this.reading.toString(); }
public String getCondition() { return this.condition.toString(); }
public String toString() { return "userid: "+getUserid()+" resourceid: "+getResourceid()+" sid: "+getSid()+
"\ntimestamp: "+getTimestamp()+" reading: "+getReading()+" condition: "+getCondition();}
}
单独的类：
public class tester {
public static void main(String[] args) {
Application.launch(TouchDisplayEmulatorController.class, args);
}
}
解决方案
不直接支持 TableView 的分页，所以我们必须自己做。请注意，问题中引用的解决方案早于（重新引入 Sorted-/FilteredList）
如今，基本方法是使用仅包含当前页面上的行的 FilteredList。此过滤列表必须是表的 itemsProperty 的值。为了也允许排序，我们需要将原始数据包装到一个 SortedList 中，并将其比较器绑定到表提供的比较器。结合所有：
items = observableArrayList(... //my data);
sortedList = new SortedList(items);
filteredList = new FilteredList(sortedList);
table.setItems(filteredList);
sortedList.comparatorProperty().bind(table.comparatorProperty());
看起来不错，不是吗？不幸的是，单击列标题时没有任何反应。原因：
- 负责排序的协作者是 sortPolicy
- 默认策略检查表的项目是否是排序列表：如果是（并且它的比较器绑定到表的），则排序留给该列表，否则回退到
FXCollections.sort(items, ...) - collections.sort 无法执行任何操作，因为过滤后的列表是不可修改的
在伪代码中：
if (items instanceof SortedList) {
return sortedList.getComparator().isBoundTo(table.getComparator());
}
try {
FXCollections.sort(items);
// sorting succeeded
return true;
} catch (Exception ex) {
// sorting failed
return false;
}
出路是实现自定义排序策略：它不仅检查表的项目是否为 sortedList，而是沿着 transformationList（如果可用）源链向上遍历，直到找到已排序（或未排序）：
ObservableList<?> lookup = items;
while (lookup instanceof TransformationList) {
if (lookup instanceof SortedList) {
items = lookup;
break;
} else {
lookup = ((TransformationList<?, ?>) lookup).getSource();
}
}
// ... same as original policy
现在我们已经准备好（完整列表的）排序 - 下一个问题是排序后分页视图应该发生什么。选项：
- 保持页面不变并更新过滤器
- 保持任何当前项目可见并更新页面
当列表的排序状态发生变化时，两者都需要触发更新，这取决于用户体验指南。
一个可运行的例子：
public class TableWithPaginationSO extends Application {
public static <T> Callback<TableView<T>, Boolean> createSortPolicy(TableView<T> table) {
// c&p of DEFAULT_SORT_POLICY except adding search up a chain
// of transformation lists until we find a sortedList
return new Callback<TableView<T>, Boolean>() {
@Override
public Boolean call(TableView<T> table) {
try {
ObservableList<?> itemsList = table.getItems();
// walk up the source lists to find the first sorted
ObservableList<?> lookup = itemsList;
while (lookup instanceof TransformationList) {
if (lookup instanceof SortedList) {
itemsList = lookup;
break;
} else {
lookup = ((TransformationList<?, ?>) lookup).getSource();
}
}
if (itemsList instanceof SortedList) {
SortedList<?> sortedList = (SortedList<?>) itemsList;
boolean comparatorsBound = sortedList.comparatorProperty()
.isEqualTo(table.comparatorProperty()).get();
return comparatorsBound;
} else {
if (itemsList == null || itemsList.isEmpty()) {
// sorting is not supported on null or empty lists
return true;
}
Comparator comparator = table.getComparator();
if (comparator == null) {
return true;
}
// otherwise we attempt to do a manual sort, and if successful
// we return true
FXCollections.sort(itemsList, comparator);
return true;
}
} catch (UnsupportedOperationException e) {
return false;
}
};
};
}
private Parent createContent() {
initData();
// wrap sorted list around data
sorted = new SortedList<>(data);
// wrap filtered list around sorted
filtered = new FilteredList<>(sorted);
// use filtered as table's items
table = new TableView<>(filtered);
addColumns();
page = new BorderPane(table);
// install custom sort policy
table.setSortPolicy(createSortPolicy(table));
// bind sorted comparator to table's
sorted.comparatorProperty().bind(table.comparatorProperty());
pagination = new Pagination(rowsPerPage, 0);
pagination.setPageCount(sorted.size() / rowsPerPage);;
pagination.setPageFactory(this::createPage);
sorted.addListener((ListChangeListener<Locale>) c -> {
// update page after changes to list
updatePage(true);
});
return pagination;
}
private Node createPage(int pageIndex) {
updatePredicate(pageIndex);
return page;
}
/**
* Update the filter to show the current page.
*/
private void updatePredicate(int pageIndex) {
int first = rowsPerPage * pageIndex;
int last = Math.min(first + rowsPerPage, sorted.size());
Predicate<Locale> predicate = loc -> {
int index = sorted.indexOf(loc);
return index >= first && index < last;
};
filtered.setPredicate(predicate);
// keep reference to first on page
firstOnPage = filtered.get(0);
}
/**
* Update the page after changes to the list.
*/
private void updatePage(boolean keepItemVisible) {
if (keepItemVisible) {
int sortedIndex = sorted.indexOf(firstOnPage);
int pageIndex = sortedIndex >= 0 ? sortedIndex / rowsPerPage : 0;
pagination.setCurrentPageIndex(pageIndex);
} else {
updatePredicate(pagination.getCurrentPageIndex());
}
}
private void addColumns() {
TableColumn<Locale, String> name = new TableColumn<>("Name");
name.setCellValueFactory(new PropertyValueFactory<>("displayName"));
TableColumn<Locale, String> country = new TableColumn<>("Country");
country.setCellValueFactory(new PropertyValueFactory<>("displayCountry"));
table.getColumns().addAll(name, country);
}
private void initData() {
Locale[] availableLocales = Locale.getAvailableLocales();
data = observableArrayList(
Arrays.stream(availableLocales)
.filter(e -> e.getDisplayName().length() > 0)
.limit(120)
.collect(toList())
);
}
private TableView<Locale> table;
private Pagination pagination;
private BorderPane page;
private ObservableList<Locale> data;
private FilteredList<Locale> filtered;
private SortedList<Locale> sorted;
private Locale firstOnPage;
private int rowsPerPage = 15;
@Override
public void start(Stage stage) throws Exception {
stage.setScene(new Scene(createContent()));
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}
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