What causes javac to issue the "uses unchecked or unsafe operations" warning
generics, java, warnings
Solution
This comes up in Java 5 and later if you're using collections without type specifiers (e.g., `Arraylist()` instead of `ArrayList<String>()`). It means that the compiler can't check that you're using the collection in a type-safe way, using generics.
To get rid of the warning, you need to be specific about what type of objects you're storing in the collection. So, instead of
List myList = new ArrayList();
use
List<String> myList = new ArrayList<String>();
In Java 7 you can shorten generic instantiation by using Type Inference.
List<String> myList = new ArrayList<>();
Problem
For example: ``` javac Foo.java Note: Foo.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. ```