如何在 JavaFX 的 XYChart 中删除“为可变参数创建未经检查的泛型数组”？

Question

I am studying JavaFX and I am also a newbie in Java. (I am using Java8 in Windows.)

Sample code is like below.

XYChart.Series series1 = new XYChart.Series();
eries1.setName("남자");
series1.setData(FXCollections.observableArrayList(
        new XYChart.Data("2015", 70),
        new XYChart.Data("2016", 40),
        new XYChart.Data("2017", 50),
        new XYChart.Data("2018", 30)
));

In this code, I can see a warning. That is,

Unchecked call to 'Data(X, Y)' as a member of raw type 'javafx.scene.chart.XYChart.Data'

Though the code works, I want to remove this warning because I am weak at Java generics programming and want to learn more about it through sample code.

What is the right way of removing that warning?

Thank you.

Answer 1

Change the lines that look like

new XYChart.Data("2015", 70)

to specify an inferred generic type using the "diamond operator" <> . Like,

new XYChart.Data<>("2015", 70)

and if using an older version of Java (without the diamond operator), provide the <X,Y> type parameters documented in XYChart.Data like

new XYChart.Data<String, Integer>("2015", 70)

Answer 2

The following gives no warnings with java 12

XYChart.Series<String, Integer> series1 = new XYChart.Series<>();
ObservableList<XYChart.Data<String, Integer>> list = FXCollections.observableArrayList();
list.add(new XYChart.Data<>("2015", 70));
list.add(new XYChart.Data<>("2016", 40));
list.add(new XYChart.Data<>("2017", 50));
list.add(new XYChart.Data<>("2018", 30));
series1.setData(list);

See my last comment to Elliot's answer. Basically you can't get rid of the warning (other than using the annotation @SuppressWarning ) when using method addAll() .