Part 1
Interview questions on Generics in java for experienced covered in this post:
What is Generics? Can you list out some
advantages of Generics?
-
Generic provides type safety and resolve type casting
problems.
-
Advantages of Generics.
1.
No explicit type casting is required.
2.
Reduce chances to throw ClassCastException.
3.
With the help of generics, we can identify which type of list
is there.
4.
If you are trying to add a heterogeneous object then you will
get a compile-time error.
-
Please refer to the below example.
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package simplifiedjava.crackedInterview;
import
java.util.ArrayList; import java.util.List; public class GenericsDemoForStringList {
public
static
void
main(String[] args) {
List<String> list
= new
ArrayList<String>();
list.add("Shweta");
list.add("Shruti");
list.add("Arpita");
System.out.println(list);
}
} Output: [Shweta, Shruti, Arpita] If you are trying to add other thanString you will get compile time error.
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What is Generic Type Parameter?
-
Type parameter is an identifier that specifies a generic type
name.
-
Type parameter is also known as the Type variable.
-
Type parameter can be used to declare the return type.
-
Please refer to the syntax.
|
class
ArrayList<T>{
add(T t);
T get(int
index); }
class
ArrayList<String>{
add(String s);
String get(int
index);
} |
-
Please refer to the below example.
|
package
simplifiedjava.crackedInterview; public class GenericTemplate<T> { T obj;
public
GenericTemplate(T obj) {
this.obj
= obj;
}
public
T getobj() {
return
obj;
}
public
void
show() {
System.out.println("Type of Object "+ obj.getClass().getName());
} } package simplifiedjava.crackedInterview; public class GenericDemo {
public
static
void
main(String[] args) {
GenericTemplate<String> str
= new
GenericTemplate<String>("Yogesh");
str.show();
System.out.println(str.getobj());
GenericTemplate<Integer> numbers
= new
GenericTemplate<Integer>(100);
numbers.show();
System.out.println(numbers.getobj());
GenericTemplate<Double> dblNum
= new
GenericTemplate<Double>(25.50);
dblNum.show();
System.out.println(dblNum.getobj());
} }
Output:
Type of Object java.lang.String
Yogesh
Type of Object java.lang.Integer
100
Type of Object java.lang.Double 25.5 |
 
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What is bounded type parameter?
-
We can bound type parameters to the particular range by using
extends keyword such types are called bounded types.
-
Please refer to the below example.
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class Test <T extends Number>{
} |
What is type interface?
- Type safety means that the compiler will validate types while compiling, and throw an error if you try to assign the wrong type to a variable.
What is type Erasure?
-
Generic provides compile-time java files all generics syntax
will be removed.
-
At runtime generics syntax that won’t be available is called
Type Erasure.
-
Java interview questions and answers all MNC - Click here
-
Basic core java interview questions and answers for freshers
- Click here
-
Core java interview questions for 3 years experience - Click here
-
Core java interview questions and answers for 3-5 years exp
- Click here
-
Core java interview questions and Answers for 5 - 7 Years exp
- Click here
-
Basic Java Interview Questions and Answers - Click here
-
Java interview questions and answers on oops - Click here
-
Java interview questions and answers on Strings - Click here
-
Java interview questions on exception handling - Click here
-
Interview questions on multithreading in java for experienced
- Click here
-
Interview questions on serialization in java for experienced
- Click here
-
Interview questions on inner class in java for experienced
- Click here
-
Interview questions on Collections in java for experienced
- Click here
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Thank you techies for visiting this blog. I hope you enjoyed this blog and got more technical knowledge. I have tried to cover all types of questions and provided examples tested on eclipse as much as I can. Guys, please don’t just mug up the questions and answers. Try to clear your concepts with examples. Try to write a code on eclipse once you read the concepts. It will help you to memorize the concepts for a very long time. Simultaneously you will be prepared for interview programs as well. It will help you to survive in the IT sector for a long time. It may be easy to crack an interview but it's really tough to survive in the IT industry with inadequate knowledge and skills. I have collected all the questions from actual interviews attended by my friends, colleagues, college mate and classmate. I have covered frequently asked questions as well as challenging questions. I have included many programs to understand the concept thoroughly. I will try to explain the concept with the help of a real-time program in eclipse. You can share more questions which are not covered in this blog or post. Always welcome your suggestions and queries. I will definitely try to resolve it. Please comment your queries and new set of questions under the comment sections. I will create a new post for those questions.
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