# Type Erasure Generics and types and checked at compile time. That means that they won't check types during runtime. While this makes them more efficient it also means that types can be lost during runtime, and for example a list of Number may end containing Strings. The erasure is a bit more complex than that, but it means that types should be set explicitly always to avoid problems. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://bernardo.gitbook.io/development-docs-java/generics/type-erasure.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.