问题：
JavaFX-使用按钮setOnAction删除形状
蒙洛华
我试图创建一个应用程序，用户在其中输入多个边，然后单击按钮，从场景中删除任何当前形状，并生成具有指定边数的形状。
虽然生成形状的逻辑正在工作，但实现root.get孩子（）。删除（形状）；似乎不起作用？
public class genShape extends Application
{
@Override
public void start(Stage stage)
{
// configure text fields for input
TextField shapeNoSidesField = new TextField();
shapeNoSidesField.setMaxWidth(23);
// configure label fields
Label shapeNoSidesLabel = new Label("Enter Desired Number Of Shape Sides:");
shapeNoSidesLabel.setTextFill(Color.RED);
shapeNoSidesLabel.setFont(Font.font("Arial", 10));
// configure generate shape button
Button generateShapeButton = new Button();
generateShapeButton.setText("Generate Shape");
// configure an HBox input components
HBox inputComponents = new HBox(40);
inputComponents.setAlignment(Pos.CENTER);
inputComponents.getChildren().addAll(shapeNoSidesLabel, shapeNoSidesField);
// configure vbox
VBox root = new VBox(50);
root.setAlignment(Pos.CENTER);
root.getChildren().addAll(inputComponents, generateShapeButton);
// Generate shape based on user Integral input. Perform input checks.
generateShapeButton.setOnAction( e ->
{
Shape shape = null;
root.getChildren().remove(shape);
// Perform input checks using helper variables. Assert no of sides field not null.
boolean shapeFieldIsEmpty = shapeNoSidesField.getText().isEmpty();
if(shapeFieldIsEmpty)
{
System.out.println("Number of Sides Field Cannot Be Empty. Please Enter a Number Between 3 and 5 Inclusive.");
display.setText("Number of Sides Field Cannot Be Empty. Please Enter a Number Between 3 and 5 Inclusive.");
}
else
{
// Retrieve user required number of sides
int numberOfSides = Integer.parseInt(shapeNoSidesField.getText());
switch(numberOfSides)
{
// User enters shape requirement of three sides (Polygon object)
case 3:
shape = new Polygon();
((Polygon) shape).getPoints().addAll(new Double[]
{
100., 70.,
100., 250.,
400., 250.
});
root.getChildren().add(shape);
break;
case 4:
shape = new Rectangle();
((Rectangle) shape).setX(150f);
((Rectangle) shape).setY(75.0f);
((Rectangle) shape).setWidth(300.0f);
((Rectangle) shape).setHeight(150.0f);
root.getChildren().add(shape);
break;
default:
break;
}
}
}
);
// create a new scene and add it to the stage
Scene scene = new Scene(root, 500, 500);
stage.setScene(scene);
stage.setTitle("Shapes");
stage.show();
}
public static void main(String[] args)
{
// TODO Auto-generated method stub
launch(args);
}
}
任何帮助都非常感谢，谢谢！
共有1个答案
田向荣
只需将shape设置为实例变量。还要注意的是，没有必要进行所有丑陋的降级。
public class genShape extends Application
{
private Shape shape ;
@Override
public void start(Stage stage)
{
// configure text fields for input
TextField shapeNoSidesField = new TextField();
shapeNoSidesField.setMaxWidth(23);
// configure label fields
Label shapeNoSidesLabel = new Label("Enter Desired Number Of Shape Sides:");
shapeNoSidesLabel.setTextFill(Color.RED);
shapeNoSidesLabel.setFont(Font.font("Arial", 10));
// configure generate shape button
Button generateShapeButton = new Button();
generateShapeButton.setText("Generate Shape");
// configure an HBox input components
HBox inputComponents = new HBox(40);
inputComponents.setAlignment(Pos.CENTER);
inputComponents.getChildren().addAll(shapeNoSidesLabel, shapeNoSidesField);
// configure vbox
VBox root = new VBox(50);
root.setAlignment(Pos.CENTER);
root.getChildren().addAll(inputComponents, generateShapeButton);
// Generate shape based on user Integral input. Perform input checks.
generateShapeButton.setOnAction( e ->
{
if (shape != null) {
root.getChildren().remove(shape);
}
// Perform input checks using helper variables. Assert no of sides field not null.
boolean shapeFieldIsEmpty = shapeNoSidesField.getText().isEmpty();
if(shapeFieldIsEmpty)
{
System.out.println("Number of Sides Field Cannot Be Empty. Please Enter a Number Between 3 and 5 Inclusive.");
display.setText("Number of Sides Field Cannot Be Empty. Please Enter a Number Between 3 and 5 Inclusive.");
}
else
{
// Retrieve user required number of sides
int numberOfSides = Integer.parseInt(shapeNoSidesField.getText());
switch(numberOfSides)
{
// User enters shape requirement of three sides (Polygon object)
case 3:
Polygon poly = new Polygon();
poly.getPoints().addAll(new Double[]
{
100., 70.,
100., 250.,
400., 250.
});
root.getChildren().add(poly);
this.shape = poly ;
break;
case 4:
Rectangle rect = new Rectangle();
rect.setX(150f);
rect.setY(75.0f);
rect.setWidth(300.0f);
rect.setHeight(150.0f);
root.getChildren().add(rect);
this.shape = rect ;
break;
default:
break;
}
}
}
);
// create a new scene and add it to the stage
Scene scene = new Scene(root, 500, 500);
stage.setScene(scene);
stage.setTitle("Shapes");
stage.show();
}
public static void main(String[] args)
{
// TODO Auto-generated method stub
launch(args);
}
}
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