Question

我只是在学习Java，到目前为止一切顺利。我正在学习JavaFX的基础知识，并编写了一个只显示一些Checkboxes控件和标签的程序。当用户点击其中一个（或任何一个）复选框时，我正在尝试使用名为响应的Label来更改文本。下面的代码仅显示了bananaCB复选框的EventHandler。

public class Main extends Application implements EventHandler {
private Label title;
private Label response;
private Label selected;
private CheckBox bananaCB;
private CheckBox mangoCB;
private CheckBox papayaCB;
private CheckBox grapfruitCB;
private String fruits;

@Override
public void start(Stage primaryStage) throws Exception{
    primaryStage.setTitle("Favorite Fruit");

    title = new Label("What fruits do you like?");
    response = new Label("");
    selected = new Label("");

    bananaCB = new CheckBox("Banana");
    mangoCB = new CheckBox("Mango");
    papayaCB = new CheckBox("Papaya");
    grapfruitCB = new CheckBox("Grapfruit");


    //Setup the stage and Scene
    FlowPane flowPaneRoot = new FlowPane(Orientation.VERTICAL,5,5);
    flowPaneRoot.setAlignment(Pos.CENTER);

    //We add all of our controls to flowPaneRoot
    flowPaneRoot.getChildren().add(title);
    flowPaneRoot.getChildren().addAll(bananaCB,mangoCB,papayaCB,grapfruitCB);
    flowPaneRoot.getChildren().add(response);
    flowPaneRoot.getChildren().add(selected);


    //Attach eventListeners to our checkboxes.


    Scene scene = new Scene(flowPaneRoot,400,250);
    primaryStage.setScene(scene);
    primaryStage.show();

}

public void showAll(){
    fruits = "";
}


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

@Override
public void handle(Event event) {
    Object fruitSelected = event.getSource();
    if (bananaCB.equals(fruitSelected)) {
        if (bananaCB.isSelected()) {
            response.setText("Banana Selected");
        } else {
            response.setText("Banana cleared");
        }
    }

}

}

我确实尝试了一个setOnAction事件处理程序，它按预期工作。我在上面的代码中注释了它，但它看起来很乱。我会在这里发布。

        bananaCB.setOnAction(new EventHandler<ActionEvent>() {
        @Override
       public void handle(ActionEvent event) {
            response.setText("Banana Selected");
        }
    });

Answer 1

我认为正确的条件是bananaCB.ischecked。

试试吧。由于方法调用错误，标签可能没有改变

Answer 2

您可以将应用程序类的事件作为事件处理程序附加到多个CheckBox es，但我不推荐它。此外，您需要使用setOnAction方法实际注册处理程序：

bananaCB.setOnAction(this);
mangoCB.setOnAction(this);
...

此外，使用相同的事件处理程序并检查所有可能的来源是不好的做法我推荐在ChangeListener属性中使用selected来代替CheckBox属性，并为每个private static CheckBox createFruitCheckBox(final String text) { CheckBox result = new CheckBox(text); ChangeListener<Boolean> listener = (observable, oldValue, newValue) -> response.setText(newValue ? text + " Selected" : text + " cleared"); result.selectedProperty().addListener(listener); return result; }使用不同的lambdas / anonymus类：

bananaCB = createFruitCheckBox("Banana");
mangoCB = createFruitCheckBox("Mango");
...

// This will come from the query, but for the example
$array = Array("aaa, bbb", "ccc, ddd, aaa", "eee, aaa, ccc", "ddd");

// Initilize an empty array for holding count values
$counterArray = Array();

// Loop through each "table row"
foreach ($array as $row)
{
    // Split the row on the comma
    $splitRow = explode(',', $row);

    // Loop through each item found on the row
    foreach ($splitRow as $item)
    {      
        // Trim to get rid of any leading/trailing spaces
        $arrayKey = trim($item);

        // Check if the array contains the values already, if yes increment otherwise creaet a record with a initial value of 1
        if (!array_key_exists($arrayKey, $counterArray))
            $counterArray[$arrayKey] = 1;
        else
            $counterArray[$arrayKey]++;
    }
}

Checkbox EventHandler不更改标签中的文本（JavaFX）

2 个答案: