How is type conversion performed when using generics in programming?

In Java, when using generics, type conversion occurs through a mechanism called type erasure. This means that during compilation, information about the specific parameter types of the generics is removed, and all generic types are replaced with their bounding type (usually Object if there are no bounds).

For example, the class List<T> at runtime is actually represented as List<Object>. The compiler inserts necessary type casts and safety checks to ensure type correctness during compilation.

Example:

List<String> list = new ArrayList<>();
list.add("Hello");
String s = list.get(0); // the compiler knows this is a String

At runtime, list.get(0) returns an Object, but the compiler automatically inserts a cast to String.

Thus, type conversion when using generics in Java is mainly a compile-time transformation with subsequent type casting at runtime, facilitated by the type erasure mechanism.