JavaFX：获取ComboBoxTableCell的组合框

Question

我想添加一个处理程序到ComboBoxTableCell内的ComboBox中的JavaFX8的TableView。我可以看到ComboBoxTableCell课程中有一个私人ComboBox值，但我不知道如何访问它。我通过setCellFactory方法告诉列使用ComboBoxTableCell。有没有办法获得ComboBox？

编辑：我想添加一个监听程序到ComboBox，它可以通过输入键来选择项目。我已经有一个正常的ComboBox，我想重复使用ComboBox中的TableCell。

Answer 1

据我所知，没有办法获得对ComboBoxTableCell的ComboBox的引用。如果那是真的，就不可能为它添加一个监听器。

另一种方法是创建包含ComboBox的自定义单元格。通过这种方法，您可以以任何您想要的方式操纵ComboBox。

import java.util.function.BiConsumer; 
import java.util.function.Function; 

import javafx.application.Application; 
import javafx.beans.property.SimpleStringProperty; 
import javafx.beans.value.ObservableValue; 
import javafx.collections.FXCollections; 
import javafx.collections.ObservableList; 
import javafx.scene.Scene; 
import javafx.scene.control.ComboBox; 
import javafx.scene.control.TableCell; 
import javafx.scene.control.TableColumn; 
import javafx.scene.control.TableView; 
import javafx.stage.Stage; 

public class ComboBoxTable extends Application { 
    @Override 
    public void start(Stage stage) { 
     int numOfCols = 2; 

     ObservableList<ObservableList<String>> tableData = FXCollections.observableArrayList(); 

     // Generate dummy data. 
     for (int i = 0; i < 10; i++) { 
      ObservableList<String> row = FXCollections.observableArrayList(); 

      for (int j = 0; j < numOfCols; j++) 
       row.add("Row" + i + "Col" + j); 

      tableData.add(row); 
     } 

     TableView<ObservableList<String>> table = new TableView<ObservableList<String>>(); 

     // Add columns to the table. 
     for (int i = 0; i < numOfCols; i++) { 
      final int j = i; 
      // The fourth argument in the method, the BiConsumer, might require 
      // an explanation. Basically we are saying that when the BiConsumer 
      // are given an ObservableList<String> and a String, we set the 
      // value of the String as the value of the element at position "j" 
      // of the row, where "j" will be the column index. 
      table.getColumns().add(addComboBoxColumn(i, "Column " + i, row -> new SimpleStringProperty(row.get(j)), 
        (row, newText) -> row.set(j, newText))); 
     } 

     table.getItems().addAll(tableData); 

     Scene scene = new Scene(table); 

     stage.setScene(scene); 
     stage.show(); 
    } 

    /** 
    * Returns a TableColumn with ComboBoxCells. 
    */ 
    private TableColumn<ObservableList<String>, String> addComboBoxColumn(int index, String name, 
      Function<ObservableList<String>, ObservableValue<String>> property, 
      BiConsumer<ObservableList<String>, String> updater) { 

     TableColumn<ObservableList<String>, String> col = new TableColumn<ObservableList<String>, String>(name); 

     col.setCellValueFactory(cellData -> property.apply(cellData.getValue())); 

     col.setCellFactory(e -> new ComboBoxCell(updater, index)); 

     return col; 
    } 

    /** 
    * A TableCell with a ComboBox in it. 
    */ 
    public class ComboBoxCell extends TableCell<ObservableList<String>, String> { 
     private ComboBox<String> comboBox = new ComboBox<String>(); 

     /** 
     * @param updater 
     *   The updater makes sure that the cell value corresponds 
     *   with the value in the ComboBox. 
     * @param colIndex 
     *   The index of this column. 
     */ 
     public ComboBoxCell(BiConsumer<ObservableList<String>, String> updater, int colIndex) { 
      comboBox.setEditable(true); 

      comboBox.getEditor().textProperty().addListener((old, oldValue, newValue) -> { 
       if (getIndex() >= 0) { 
        // We provide the BiConsumer.accept() with an 
        // ObservableList<String> and a String. The BiConsumer will 
        // do the operation specified in the definition we provided 
        // in addColumn() using these two objects. 
        updater.accept(getTableView().getItems().get(getIndex()), (String) newValue); 
       } 
      }); 
     } 

     @Override 
     protected void updateItem(String item, boolean empty) { 
      super.updateItem(item, empty); 
      if (empty) { 
       setGraphic(null); 
      } else { 
       // If we don't check if this value is the same as the old one, 
       // the cursor is moved to the beginning of the editor every time 
       // anything is typed. 
       if (!item.equals(comboBox.getEditor().getText())) { 
        comboBox.getEditor().setText(item); 
       } 
       setGraphic(comboBox); 
      } 
     } 
    } 

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