将 Arraylist 中的文本添加到 TextArea javafx

在仔细查看您的代码后，我发现了很多问题.回答你原来的问题.您需要 SelectionModel's ItemProperty 上的侦听器来更新 TextArea.

After taking a closer look at your code, I noticed a ton of problems. To answer your original question. You need a listener on the SelectionModel's ItemProperty to updated the TextArea.

    cats.getSelectionModel().selectedItemProperty().addListener((obs, oldAnimal, newAnimal) -> {
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append("Name: ").append(newAnimal.getName()).append(System.lineSeparator());
        stringBuilder.append("Type: ").append(newAnimal.getType()).append(System.lineSeparator());
        stringBuilder.append("About: ").append(newAnimal.getAbout()).append(System.lineSeparator());        

        description.setText(stringBuilder.toString());
    });

第一个问题:

ListView<String> cats = new ListView<>();
cats.setPrefSize(90, 200);
cats.getItems().addAll(
        "First cat",
        "Second cat" 
);

看起来您希望 ListView 保存 Animal 对象，但您使用的是 String 对象.

It appears you want the ListView to hold Animal objects, but you are using String objects.

修复

ListView<Animal> cats = new ListView<>();
cats.getItems().add(new Animal("First cat", "cats", "is small and fluffy"));
cats.getItems().add(new Animal("Second cat", "cats", "is big and fluffy"));

第二个问题:现在 ListView 正在处理 Animal 对象，我们需要使用 ListView's CellFActory 告诉 ListView 显示什么文本.在这种情况下，将显示名称.

Second Problem: Now that the ListView is handling Animal objects, we need to use the ListView's CellFActory to tell the ListView what text to display. In this case, the name will be displayed.

    cats.setCellFactory((ListView<Animal> param) -> {
        ListCell<Animal> cell = new ListCell<Animal>() {                
            @Override
            protected void updateItem(Animal item, boolean empty) {
                super.updateItem(item, empty);
                if (item != null) {
                    setText(item.getName());
                } else {
                    setText("");
                }
            }
        };

        return cell;
    }); 

既然这两件事都做完了，就可以加上原来的问题代码了.上面的代码根据在 ListView 中选择的项目来更改 TextArea 的 文本.

Now that these two things are done, the original question code can be added. The code above that changes the TextArea's text depending on which item is selected in the ListView.

完整代码:

主要

    import javafx.application.Application;
    import javafx.scene.Scene;
    import javafx.scene.control.Label;
    import javafx.scene.control.ListCell;
    import javafx.scene.control.ListView;
    import javafx.scene.control.TextArea;
    import javafx.scene.layout.HBox;
    import javafx.scene.layout.VBox;
    import javafx.scene.text.Font;
    import javafx.stage.Stage;

    /**
     * JavaFX App
     */
    public class App extends Application {

        @Override
        public void start(Stage primaryStage) {
            ListView<Animal> cats = new ListView<>();
            cats.getItems().add(new Animal("First cat", "cats", "is small and fluffy"));
            cats.getItems().add(new Animal("Second cat", "cats", "is big and fluffy"));

            cats.setCellFactory((ListView<Animal> param) -> {
                ListCell<Animal> cell = new ListCell<Animal>() {                
                    @Override
                    protected void updateItem(Animal item, boolean empty) {
                        super.updateItem(item, empty);
                        if (item != null) {
                            setText(item.getName());
                        } else {
                            setText("");
                        }
                    }
                };

                return cell;
            }); 
            cats.setPrefSize(90, 200);           

            TextArea description = new TextArea();
            description.setMaxSize(300, 200);
            description.setWrapText(true);

            cats.getSelectionModel().selectedItemProperty().addListener((obs, oldAnimal, newAnimal) -> {
                StringBuilder stringBuilder = new StringBuilder();
                stringBuilder.append("Name: ").append(newAnimal.getName()).append(System.lineSeparator());
                stringBuilder.append("Type: ").append(newAnimal.getType()).append(System.lineSeparator());
                stringBuilder.append("About: ").append(newAnimal.getAbout()).append(System.lineSeparator());        

                description.setText(stringBuilder.toString());
            });

            VBox vbox = new VBox();
            Label heading = new Label("Cats");
            heading.setFont(new Font("Times new Roman", 20));

            HBox layout = new HBox(cats, description);

            vbox.getChildren().addAll(heading, layout);

            Scene scene = new Scene(vbox, 420, 250);
            primaryStage.setScene(scene);
            primaryStage.show();
        }

        public static void main(String[] args) {
            launch();
        }    
    }

我的动物课:(你没有发布你的)

/**
 *
 * @author blj0011
 */
class Animal {
    private String name;
    private String type;
    private String about;

    public Animal(String name, String type, String about) {
        this.name = name;
        this.type = type;
        this.about = about;
    }

    public String getAbout() {
        return about;
    }

    public void setAbout(String about) {
        this.about = about;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("Animals{name=").append(name);
        sb.append(", type=").append(type);
        sb.append(", about=").append(about);
        sb.append('}');
        return sb.toString();
    }    
}