Type Erasure

How generics work at runtime

Interview Relevant: Understanding limitations
6 min read

Type Erasure

Java generics use type erasure, meaning generic type information is removed at runtime.

Code Examples

Type erasure at runtime

java
1
2List<String> l1 = new ArrayList<>();
3List<Integer> l2 = new ArrayList<>();
4
5System.out.println(l1.getClass() == l2.getClass()); // true
6

Use Cases

  • Backward compatibility
  • Understanding runtime behavior

Common Mistakes to Avoid

  • Expecting generic info at runtime
  • Using instanceof with generics