ListView-removeAll不起作用? [英] ListView - removeAll doesn't work?
问题描述
(这是Carl Dea的"JavaFX 2.0示例"一书中的代码-该代码示例可在Apress免费获得，所以我确定他们不介意我在这里使用它)
(This is code from the book "JavaFX 2.0 by example" by Carl Dea - the code example is freely available at Apress so I'm sure they don't mind me using it here)
我有完美的示例代码
package javafx2introbyexample.chapter1.recipe1_11;
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.VPos;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ListView;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
/**
*
* @author cdea
*/
public class CreatingAndWorkingWithObservableLists extends Application {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
Application.launch(args);
}
@Override
public void start(Stage primaryStage) {
primaryStage.setTitle("Chapter 1-11 Creating and Working with ObservableLists");
Group root = new Group();
Scene scene = new Scene(root, 400, 250, Color.WHITE);
// create a grid pane
GridPane gridpane = new GridPane();
gridpane.setPadding(new Insets(5));
gridpane.setHgap(10);
gridpane.setVgap(10);
// candidates label
Label candidatesLbl = new Label("Candidates");
GridPane.setHalignment(candidatesLbl, HPos.CENTER);
gridpane.add(candidatesLbl, 0, 0);
Label heroesLbl = new Label("Heroes");
gridpane.add(heroesLbl, 2, 0);
GridPane.setHalignment(heroesLbl, HPos.CENTER);
// candidates
final ObservableList<String> candidates = FXCollections.observableArrayList("Superman",
"Spiderman",
"Wolverine",
"Police",
"Fire Rescue",
"Soldiers",
"Dad & Mom",
"Doctor",
"Politician",
"Pastor",
"Teacher");
final ListView<String> candidatesListView = new ListView<String>(candidates);
candidatesListView.setPrefWidth(150);
candidatesListView.setPrefHeight(150);
gridpane.add(candidatesListView, 0, 1);
// heros
final ObservableList<String> heroes = FXCollections.observableArrayList();
final ListView<String> heroListView = new ListView<String>(heroes);
heroListView.setPrefWidth(150);
heroListView.setPrefHeight(150);
gridpane.add(heroListView, 2, 1);
// select heroes
Button sendRightButton = new Button(">");
sendRightButton.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
String potential = candidatesListView.getSelectionModel().getSelectedItem();
if (potential != null) {
candidatesListView.getSelectionModel().clearSelection();
candidates.remove(potential);
heroes.add(potential);
}
}
});
// deselect heroes
Button sendLeftButton = new Button("<");
sendLeftButton.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
String notHero = heroListView.getSelectionModel().getSelectedItem();
if (notHero != null) {
heroListView.getSelectionModel().clearSelection();
heroes.remove(notHero);
candidates.add(notHero);
}
}
});
VBox vbox = new VBox(5);
vbox.getChildren().addAll(sendRightButton,sendLeftButton);
gridpane.add(vbox, 1, 1);
GridPane.setConstraints(vbox, 1, 1, 1, 2,HPos.CENTER, VPos.CENTER);
root.getChildren().add(gridpane);
primaryStage.setScene(scene);
primaryStage.show();
}
}
它是用于在两个列表视图之间来回移动人员，一次一个的代码.我想做的是使一键选择并移动多个人成为可能.
It is code for moving persons back and forth between two listviews, one at a time. What I want to do is make it possible to select and move several persons in one click.
我要更改的相关摘录是:
The relevant excerpts I want to change are:
final ListView<String> candidatesListView = new ListView<String>(candidates);
candidatesListView.setPrefWidth(150);
candidatesListView.setPrefHeight(150);
gridpane.add(candidatesListView, 0, 1);
// heros
final ObservableList<String> heroes = FXCollections.observableArrayList();
final ListView<String> heroListView = new ListView<String>(heroes);
...
// select heroes
Button sendRightButton = new Button(">");
sendRightButton.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
String potential = candidatesListView.getSelectionModel().getSelectedItem();
if (potential != null) {
candidatesListView.getSelectionModel().clearSelection();
candidates.remove(potential);
heroes.add(potential);
}
}
});
// deselect heroes
Button sendLeftButton = new Button("<");
sendLeftButton.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
String notHero = heroListView.getSelectionModel().getSelectedItem();
if (notHero != null) {
heroListView.getSelectionModel().clearSelection();
heroes.remove(notHero);
candidates.add(notHero);
}
}
});
我尝试更改的内容:
首先，我添加以下导入:
First I add the following import:
import javafx.scene.control.SelectionMode;
然后我添加行
candidatesListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
heroListView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
在两个列表的各自声明下.
beneath the respective declarations of the two lists.
最后，我将事件按钮的处理代码更改为
Lastly I change the code of the handling of the eventbutton to
public void handle(ActionEvent event) {
ObservableList<String> potential = candidatesListView.getSelectionModel().getSelectedItems();
if (potential != null) {
System.out.println(potential);
candidates.removeAll(potential);
heroes.addAll(potential);
candidatesListView.getSelectionModel().clearSelection();
}
}
那是-我将其更改为getSelectedItem_s_，然后我添加了all和removeAll，而不仅仅是添加/删除了一个人.当我尝试移动多个人时，这只是将listView留为空白.有什么作用?
That is- I change it to getSelectedItem_s_, then I addAll and removeAll instead of merely adding/removing one person. This just leaves the listView blank when I try to move several people over. What gives?
Ps.我还尝试通过遍历潜在"列表来一次添加/删除几个人，但这也给出了错误的结果.
Ps. I also tried just adding/removing several people one at a time by iterating over the list "potential", but that also gave the wrong result.
推荐答案
不幸的是，您遇到了一个错误: http ://javafx-jira.kenai.com/browse/RT-24367
Unfortunately you've met a bug: http://javafx-jira.kenai.com/browse/RT-24367
接下来的原始问题是:ListView.getSelectionMode()返回其可观察列表的一部分，而不是副本.因此，从该列表中删除会导致各种问题.
The original problem is next: ListView.getSelectionMode() returns part of it's observable list but not the copy. So removing from that list leads to various issues.
使用下一个复制列表的代码，然后再从列表中删除项目
Use next code which copies list before removing items from it:
sendRightButton.setOnAction(new EventHandler<ActionEvent>() {
public void handle(ActionEvent event) {
ObservableList<String> potential =
FXCollections.observableArrayList( //copy
candidatesListView.getSelectionModel().getSelectedItems());
if (potential != null) {
heroes.addAll(potential);
candidates.removeAll(potential);
candidatesListView.getSelectionModel().clearSelection();
}
}
});
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