我有一个ListView与我自己的ListCell<MyObject>实现。通过网络信号，我收到了应该更改的ListCell索引。通过ListView获取ListCell
超过listView.getItems().get(index);访问模型没有问题，但是我想用接收到的索引对listCell进行布局更改，并将索引+1更改为ListCell;
如何通过ListView访问ListCell？
我寻找这样的方法：
listView.getListCell(index);
不幸的是，现在没有API通过索引来获取列表细胞或让所有儿童（listcells）的ListView控件。一种解决方案可以是，在MyObject类中定义一个新的StringProperty specialIndicator。
class MyObject {
....//u r properties
private StringProperty specialIndicator;
当你永远从设置对象的这一specialIndicator财产网络信号得到指数和做的ListView forcerefresh
public void onReceivedNetWorkSignalIndex() {
listView.getItems().get(indexFromService).setSpecialIndicator("selected");
listView.getItems().get(indexFromService+1).setSpecialIndicator("selectedplusone");
//force refresh listview (it will trigger cellFactory again so that you can manipulate layout)
listView.setItems(null);
listView.setItems(allObjects);
}
因为您已经有了自定义对象的ListView，我假设你已经有了定制cellFactory（如果不是你要创建一个），修改自定义电池工厂来处理这个特殊的指标
listView.setCellFactory(new Callback<ListView<MyObject>, ListCell<MyObject>>() {
@Override
public ListCell<MyObject> call(ListView<MyObject> myObjectListView) {
ListCell<MyObject> cell = new ListCell<MyObject>(){
@Override
protected void updateItem(MyObject myObject, boolean b) {
super.updateItem(myObject, b);
if(myObject != null) {
setText(myObject.getName());
if("selected".equalsIgnoreCase(myObject.getSpecialIndicator())) {
System.out.println("Setting new CSS/graphics for index retun from service." + myObject.getName());
} else if("selectedplusone".equalsIgnoreCase(myObject.getSpecialIndicator())) {
System.out.println("Setting new CSS/Graphics for index+1 returned from service" + myObject.getName());
}
myObject.setSpecialIndicator(""); // reset it back to empty
}
}
};
return cell;
}
});
这里是整个示例应用程序，Y你可以查看它（如果上述解释不清楚）。 
public class ListViewTest extends Application {
@Override
public void start(Stage stage) throws Exception {
VBox root = new VBox();
final ObservableList<MyObject> allObjects = FXCollections.observableArrayList(new MyObject("object0"), new MyObject("object1"),new MyObject("object2"),new MyObject("object3"),new MyObject("object4"));
final ListView<MyObject> listView = new ListView<>(allObjects);
listView.setCellFactory(new Callback<ListView<MyObject>, ListCell<MyObject>>() {
@Override
public ListCell<MyObject> call(ListView<MyObject> myObjectListView) {
ListCell<MyObject> cell = new ListCell<MyObject>(){
@Override
protected void updateItem(MyObject myObject, boolean b) {
super.updateItem(myObject, b);
if(myObject != null) {
setText(myObject.getName());
if("selected".equalsIgnoreCase(myObject.getSpecialIndicator())) {
System.out.println("Setting new CSS/graphics for index retun from service." + myObject.getName());
setText("I am selected Index from Service");
} else if("selectedplusone".equalsIgnoreCase(myObject.getSpecialIndicator())) {
System.out.println("Setting new CSS/Graphics for index+1 returned from service" + myObject.getName());
setText("I am selected Index +1 from Service");
}
myObject.setSpecialIndicator(""); // reset it back to empty
}
}
};
return cell;
}
});
Button serviceIndex2 = new Button("ServiceIndex2");
serviceIndex2.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent actionEvent) {
int indexFromService =2;
listView.getItems().get(indexFromService).setSpecialIndicator("selected");
listView.getItems().get(indexFromService+1).setSpecialIndicator("selectedplusone");
listView.setItems(null);
listView.setItems(allObjects);
}
});
root.getChildren().addAll(listView,serviceIndex2);
Scene scene = new Scene(root,500,500);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
class MyObject {
private StringProperty name;
private StringProperty specialIndicator;
MyObject(String name) {
this.name = new SimpleStringProperty(name);
this.specialIndicator = new SimpleStringProperty();
}
public String getName() {
return name.get();
}
public StringProperty nameProperty() {
return name;
}
public void setName(String name) {
this.name.set(name);
}
public String getSpecialIndicator() {
return specialIndicator.get();
}
public StringProperty specialIndicatorProperty() {
return specialIndicator;
}
public void setSpecialIndicator(String specialIndicator) {
this.specialIndicator.set(specialIndicator);
}
}
}
这里有一个比较简单的方法，即只有一个“选择”索引。在这里我创建一个属性来保存选定的索引，单元格工厂只是观察它，以及单元格的项目属性和索引属性，并通过绑定设置文本。如果需要，你可以做类似的设置图形。
import java.util.concurrent.Callable;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.control.TextField;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import javafx.util.Callback;
public class ListViewStyleAroundSelection extends Application {
@Override
public void start(Stage primaryStage) {
final ListView<String> listView = new ListView<>();
for (int i=1; i<=20; i++) {
listView.getItems().add("Item "+i);
}
final HBox controls = new HBox(5);
final Button button = new Button("Set selection");
final TextField indexField = new TextField();
final IntegerProperty selectionIndex = new SimpleIntegerProperty();
button.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
try {
selectionIndex.set(Integer.parseInt(indexField.getText()));
} catch (NumberFormatException nfe) {
indexField.setText("");
}
}
});
controls.getChildren().addAll(new Label("Enter selection index:"), indexField, button);
final BorderPane root = new BorderPane();
root.setCenter(listView);
root.setBottom(controls);
listView.setCellFactory(new Callback<ListView<String>, ListCell<String>>() {
@Override
public ListCell<String> call(ListView<String> lv) {
final ListCell<String> cell = new ListCell<>();
cell.textProperty().bind(Bindings.createStringBinding(new Callable<String>() {
@Override
public String call() throws Exception {
if (cell.getItem() == null) {
return null ;
} else {
switch (cell.getIndex() - selectionIndex.get()) {
case -1: return cell.getItem() + " (selected item below)";
case 0: return cell.getItem() + " (selected)";
case 1: return cell.getItem() + " (selected item above)";
default: return cell.getItem();
}
}
}
}, cell.itemProperty(), cell.indexProperty(), selectionIndex));
return cell;
}
});
final Scene scene = new Scene(root, 600, 400);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
这是一个稍微复杂的版本。这里我有一个自定义数据类型，其中包含一个布尔属性。该更新将指定项的布尔属性设置为true。单元格工厂创建一个单元格，并观察当前项目和之前项目的选定属性。然后，像以前一样，它使用绑定来更新单元格的文本。
import java.util.concurrent.Callable;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.binding.BooleanBinding;
import javafx.beans.binding.IntegerBinding;
import javafx.beans.binding.ObjectBinding;
import javafx.beans.binding.StringBinding;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleBooleanProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.beans.value.ObservableValue;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.control.TextField;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import javafx.util.Callback;
public class ListViewStyleAroundSelection extends Application {
@Override
public void start(Stage primaryStage) {
final ListView<MyDataType> listView = new ListView<>();
for (int i=0; i<=20; i++) {
listView.getItems().add(new MyDataType("Item "+i, false));
}
final HBox controls = new HBox(5);
controls.setPadding(new Insets(5));
final Button button = new Button("Set selection");
final TextField indexField = new TextField();
button.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent event) {
try {
int index = Integer.parseInt(indexField.getText());
if (index >= 0 && index < listView.getItems().size()) {
final MyDataType item = listView.getItems().get(index);
item.setSelected(! item.isSelected());
}
} catch (NumberFormatException nfe) {
indexField.setText("");
}
}
});
controls.getChildren().addAll(new Label("Enter selection index:"), indexField, button);
final BorderPane root = new BorderPane();
root.setCenter(listView);
root.setBottom(controls);
listView.setCellFactory(new Callback<ListView<MyDataType>, ListCell<MyDataType>>() {
@Override
public ListCell<MyDataType> call(ListView<MyDataType> lv) {
final ListCell<MyDataType> cell = new ListCell<>();
final IntegerBinding previousIndex = cell.indexProperty().subtract(1);
final ObjectBinding<MyDataType> previousItem = Bindings.valueAt(listView.getItems(), previousIndex);
final BooleanBinding previousItemSelected = Bindings.selectBoolean(previousItem, "selected");
final StringBinding thisItemName = Bindings.selectString(cell.itemProperty(), "name");
final BooleanBinding thisItemSelected = Bindings.selectBoolean(cell.itemProperty(), "selected");
cell.textProperty().bind(Bindings.createStringBinding(new Callable<String>() {
@Override
public String call() throws Exception {
if (cell.getItem() == null) {
return null ;
} else {
String value = cell.getItem().getName();
if (thisItemSelected.get()) {
value = value + " (selected) " ;
} else if (previousItemSelected.get()) {
value = value + " (selected item is above)";
}
return value ;
}
}
}, thisItemName, thisItemSelected, previousItemSelected));
return cell;
}
});
final Scene scene = new Scene(root, 600, 400);
primaryStage.setScene(scene);
primaryStage.show();
}
public static class MyDataType {
private final BooleanProperty selected ;
private final StringProperty name ;
public MyDataType(String name, boolean selected) {
this.name = new SimpleStringProperty(this, "name", name);
this.selected = new SimpleBooleanProperty(this, "selected", selected);
}
public final String getName() {
return name.get();
}
public final void setName(String name) {
this.name.set(name);
}
public final StringProperty nameProperty() {
return name ;
}
public final boolean isSelected() {
return selected.get();
}
public final void setSelected(boolean selected) {
this.selected.set(selected);
}
public final BooleanProperty selectedProperty() {
return selected;
}
}
public static void main(String[] args) {
launch(args);
}
}
非常感谢你，你帮了我很多！但有什么令人失望的，这是不可能与存在的API ...;） –
应该可以只使用侦听器和/或绑定在单元实现;不应该有任何需要做丑陋的“力量更新”。例如，你可以添加一个监听器到像'Bindings.valueAt（listView.getItems（），indexProperty（）。subtract（1））'（或类似的东西）：这将观察当前索引列表中的项目 - 1，如果有任何更改（包括索引），将会更新。如果需要，可以将该Binding表达式与Bindings.select结合使用以获取对象内的属性。 –