Java Generics Interview Questions And Answers (2024)

Generic in Java | Java Generic Interview Questions | What is Generics in Java | Generics in Java Example

Generics is used for type safty or you can say that resolve the typeCasting problem in java. Java Generics were added in J2SE 5 to help with type safety in programming. They make the code more reliable by catching errors during the compilation phase.

Here is the list of questions, we will discuss some of the most asked Enum interview questions, like as : Generic in Java or Java Generic Interview Questions or What is Generics in Java or Generics in Java Examplee

1). What is Generic in Java ? (Most Imp Questions)

Before generics, you could store any kind of objects in a collection. Now, with generics, Java programmers are required to specify the type of objects they want to store, which helps in preventing unexpected errors.

Note: Generics add that type of safety feature.

2). Advantage of Generic in Java ? (Most Imp Questions)

There is mainly 3 advatage of Generic:

1). Type Safty: After Generics we can honld only one type of object at a time but Before Generics we can store any or various types.

Example: List<Integer> list = new ArrayList<Integer>();

2). Type casting is not required: Before Generics we don’t need to typecast the object but after Generics, we need to type cast.

Example: String s = (String) list.get(0);//typecasting

3). Compile-Time Checking: When we check at compile time then that problem will not occur at runtime.

Example:

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

list.add(“Poona”);

list.add(11);//Compile Time Error because type String & we are storing Integer type object

4). How to create a Generic class in Java?

We can declare a class, Like as following syntax:

class MyClassGeneric<T>

Note: We can use any type parameter instead of T.

5). What are the different type parameters?

Type parameters are the keyword that we provide during declaring the class or method. There are totally different five commonly used type parameters:

• T – Type

• V – Value

• K – Key

• E – Element

• N – Number

6). What is the purpose of generics in Java?

Generics in Java are used to provide type safety and to allow developers to write code that can work with multiple types while still providing compile-time type checks. This helps to prevent runtime errors caused by type mismatches and allows for more efficient code, as the compiler can perform more optimizations when it knows the specific types being used.

it is used in 3 ways:

• Type checking at Compile time: The Java compiler applies type checking to generic code at compile time and throes errors for type safety violations.

• Removed the need for implicit casting: Java code that uses generics does not need explicit casting, whereas the code that is non-generic requires explicit casting.

• Generic algorithms implementations: By using generics, programmers can develop generic algorithms designed to work on collections of different types that are type-safe and easier to use.

7). What is a wildcard in Java generics? Give an example of its usage.

A wildcard in Java generics is a placeholder for an unknown type. It is denoted with a question mark (?), and it can be used

in situations where the exact type is not important or not known. For example, you might use a wildcard when declaring a method

that accepts a list of any type, such as

public void printArrayList(ArrayList<?> myList)

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