Java’s type erasure mechanism in generics ensures compatibility with older Java versions by removing generic type information during compilation. This process involves replacing all generic type parameters with their bounds (or `Object` if unbounded) and inserting necessary casts for type safety. For example, a generic class like `Box<T>`:

public class Box<T> {
private T item;
public void set(T item) { this.item = item; }
public T get() { return item; }
}

after type erasure, it becomes:

public class Box {
private Object item;
public void set(Object item) { this.item = item; }
public Object get() { return item; }
}

To avoid `ClassCastException` and ensure type safety, follow these guidelines:

1. Bounded Type Parameters: Limit types with bounds to ensure correct usage.

public class NumberBox<T extends Number> { … }

2. Use Generics with Collections: Enforce type safety.

List<String> strings = new ArrayList<>();

3. Type Inference with Diamond Operator: Let the compiler infer types.

Box<String> stringBox = new Box<>();

4. Generic Methods: Ensure type-safe operations.

public static <T> void addItemToList(List<T> list, T item) { list.add(item); }

5. Avoid Raw Types: Prevent unsafe casts.

Box<String> box = new Box<>();

By adhering to these practices, you can create type-safe generic classes and methods in Java.