Java wildcard generic as return warning in Eclipse and SonarQube
generics, java, return, sonarqube
Solution
So how can I fix this warning ?
You can use a type parameter for your class :
public class GridModelHolder<T> {
private List<T> gridModel;
public List<T> getGridModel() {
return gridModel;
}
}
The client code can then decide what type of `List` `GridModelHolder` holds :
`GridModelHolder<String> gridModelHolder = new GridModelHolder<String>(new ArrayList<String>);`
However, if you insist on using raw types, you can either suppress the warnings or simply have a List of objects (Neither of these are recommended)
@SuppressWarnings("unchecked")
public class GridModelHolder {
private List gridModel;
public List getGridModel() {
return gridModel;
}
}
OR
public class GridModelHolder {
private List<Object> gridModel;
public List<Object> getGridModel() {
return gridModel;
}
}
Problem
``` private List gridModel; public List getGridModel() { return gridModel; } ``` Eclipse shows a warning: List is a raw type. References to generic type List should be parameterized. Changing the code to below will remove the warning ``` private List<?> gridModel; public List<?> getGridModel() { return gridModel; } ``` However the above code shows a Major pitfall error in SonarQube which says: Remove usage of generic wildcard type. Generic wildcard types should not be used in return parameters So how can I fix this warning? I see a similar question here but could not find the solution . Using `Class<? extends Object>` did not remove Sonar warning.