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In Java, the use of raw types refers to using a generic class or interface without specifying a type parameter. While Java allows the use of raw types for backward compatibility with code written before the introduction of generics in Java 5, it is considered a best practice to avoid raw types altogether. Using raw types can lead to runtime errors, reduce type safety, and make your code harder to understand and maintain.

A raw type is a name for a generic class or interface without its type parameters. For example, using `List` instead of `List<String>` is considered using a raw type. When you use a raw type, you lose the benefits of generics, such as type checking at compile-time, which can lead to unexpected ClassCastExceptions at runtime.

Here’s an example of using a raw type in Java:

```java import java.util.ArrayList; import java.util.List;

public class RawTypeExample {

   public static void main(String[] args) {
       List rawList = new ArrayList(); // Raw type
       rawList.add("String");
       rawList.add(10); // No compile-time error, but could cause issues later

       for (Object item : rawList) {
           System.out.println(item);
       }
   }

In this example, `rawList` is declared as a raw type `List`. This allows the addition of any type of object to the list, which can lead to issues when processing the list elements, as the type safety provided by generics is lost.

The primary problem with raw types is the loss of type safety. Without generics, you cannot enforce the types of objects that can be added to a collection or passed to a method. This lack of enforcement can lead to runtime exceptions, such as ClassCastException, when you try to retrieve and cast elements from a raw type collection.

Here’s how the previous example can be refactored to avoid raw types and gain type safety:

```java import java.util.ArrayList; import java.util.List;

public class GenericTypeExample {

   public static void main(String[] args) {
       List stringList = new ArrayList<>(); // Type-safe list
       stringList.add("String");
       // stringList.add(10); // Compile-time error, preventing incorrect type addition

       for (String item : stringList) {
           System.out.println(item);
       }
   }

In this refactored example, `stringList` is declared as a `List<String>`, making it type-safe. Attempting to add an integer to the list would result in a compile-time error, thus preventing runtime issues and improving code reliability.

Generics offer several benefits, including type safety, code reusability, and clearer code. By specifying the type parameters, you ensure that only objects of the specified type can be added to collections or passed to methods, reducing the likelihood of runtime errors. Generics also make the code more readable by making the types of variables and return values explicit.

One of the major advantages of avoiding raw types is that it reduces the risk of ClassCastException at runtime. When using generics, the compiler enforces type constraints, preventing incorrect type assignments at compile time. This early detection of type errors makes the code more robust and less prone to runtime failures.

Consider the following scenario where generics prevent a potential ClassCastException:

```java import java.util.ArrayList; import java.util.List;

public class SafeTypeExample {

   public static void main(String[] args) {
       List intList = new ArrayList<>();
       intList.add(1);
       intList.add(2);
       intList.add(3);

       // No need for explicit casting, compiler ensures correct types
       for (Integer number : intList) {
           System.out.println(number);
       }
   }

In this example, the use of generics ensures that only integers are added to the list, and there’s no need for explicit casting when retrieving elements from the list. This type safety eliminates the risk of ClassCastException and simplifies the code.

While it’s best to avoid raw types in new code, you may encounter raw types when working with legacy code. In such cases, it’s advisable to refactor the code to use generics wherever possible. Refactoring to generics not only improves type safety but also aligns the code with modern Java practices, making it easier to maintain and extend.

When refactoring legacy code that uses raw types, start by identifying the raw types and then introduce the appropriate type parameters. This process may involve analyzing the code to determine the expected types and making incremental changes to ensure that the code remains functional while improving type safety.

To make the most of generics in Java, follow these best practices: - Always specify type parameters for collections and methods. - Use bounded wildcards (e.g., `<? extends T>`) to create flexible APIs. - Prefer `List<?>` over raw `List` when you need to work with collections of unknown types. - Avoid using raw types even in method signatures and variables.

In conclusion, avoiding raw types is a best practice in Java that enhances type safety, reduces runtime errors, and makes your code more readable and maintainable. By embracing generics, you can create more robust and reliable code that leverages the full power of the Java type system. While legacy code may still contain raw types, refactoring to generics is a worthwhile investment that will pay off in terms of code quality and maintainability.

For more information on generics and avoiding raw types in Java, consider exploring the following resources:

• https://docs.oracle.com/javase/tutorial/java/generics/index.html
• https://en.wikipedia.org/wiki/Generics_in_Java
• https://github.com/iluwatar/java-design-patterns/tree/master/generics

These resources provide additional insights and best practices for using generics effectively in Java.

Fair Use Sources:

• Don’t use raw types
• Java Best Practices and Core Guidelines
• Effective Java on DuckDuckGo - B078H61SCH (EffJav 2017)
• The Borg

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