JavaFX 控件 ComboBox

ComboBox

基礎使用

ComboBox<String> comboBox = new ComboBox<>();
comboBox.getItems().addAll("item1", "item2", "item3", "item4", "item5");
//數據源爲空時顯示
comboBox.setPlaceholder(new Label("Placeholder"));
//設置可編輯
comboBox.setEditable(true);
comboBox.setPromptText("PromptText");
//設置可見行數, 超過顯示滾動條
comboBox.setVisibleRowCount(3);

comboBox.editorProperty().addListener(new ChangeListener<TextField>() {
    @Override
    public void changed(ObservableValue<? extends TextField> observable, TextField oldValue, TextField newValue) {
    }
});
comboBox.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<String>() {
    @Override
    public void changed(ObservableValue<? extends String> observable, String oldValue, String newValue) {
    }
});

自定義對象

Student student1 = new Student("Student1", 10, 1);
Student student2 = new Student("Student2", 11, 2);
Student student3 = new Student("Student3", 12, 3);

ComboBox<Student> comboBox = new ComboBox<>();
comboBox.getItems().addAll(student1, student2, student3);
//數據源爲空時顯示
comboBox.setPlaceholder(new Label("Placeholder"));
comboBox.setValue(student2);
//設置可編輯
comboBox.setEditable(true);
comboBox.setConverter(new StringConverter<Student>() {
    @Override
    public String toString(Student object) {
        if (object == null) {
            return "";
        }
        return object.name + "-" + object.id;
    }

    @Override
    public Student fromString(String string) {
        //接收輸入框的值
        System.out.println("string = " + string);
        comboBox.getItems().add(new Student(string, 1, 99));
        return null;
    }
});

comboBox.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<Student>() {
    @Override
    public void changed(ObservableValue<? extends Student> observable, Student oldValue, Student newValue) {

    }
});

自定義 Item

comboBox.setCellFactory(new Callback<ListView<String>, ListCell<String>>() {
    @Override
    public ListCell<String> call(ListView<String> param) {
        return new ListCell<String>() {
            @Override
            protected void updateItem(String item, boolean empty) {
                super.updateItem(item, empty);
                //this 爲 ListCell 子類
                if (!empty) {
                    this.setStyle("-fx-text-fill: #0aa");
                    this.setText(item);
                    this.setGraphic(new ImageView("image\\stash.png"));
                }
            }
        };
    }
});

comboBox.setCellFactory(new Callback<ListView<Student>, ListCell<Student>>() {
    @Override
    public ListCell<Student> call(ListView<Student> param) {
        return new ListCell<Student>() {
            @Override
            protected void updateItem(Student item, boolean empty) {
                super.updateItem(item, empty);
                if (!empty) {
                    //可以直接獲取Converter中的toString()結果
                    this.setText(comboBox.getConverter().toString(item));
                    this.setFont(Font.font(20));
                    this.setTextFill(Paint.valueOf("#088"));
                }else {
                    setText(null);
                    setGraphic(null);
                }
            }
        };
    }
});

修改 Item 值刷新列表

ObservableList<Student> items = comboBox.getItems();
items.get(index).name = "修改後";
SingleSelectionModel<Student> selectionModel = comboBox.getSelectionModel();
selectionModel.clearSelection();
selectionModel.select(index);