Part 14
Core java interview questions and answers for 3-5 years experience covered in this post:
What are the primitive functions?
-
Primitives cannot use generic type argument, Java 8 has
provided some primitives functions for performance improvement.
-
There are 15 primitive functions.
1.
IntFunction<R> :
§
If your input is always int primitive then we should use this
function.
§ Method:
R apply(int
value);
2.
LongFunction<R>:
§
If your input is always long primitive then we should use
this function.
§ Method:
R apply(long
value);
3.
DoubleFunction<R>:
§
If your input is always double primitive then we should use
this function.
§ Method:
R apply(double
value);
4.
ToIntFunction<T>:
§
Input type can be anything but return type is always
int.
§ Method:
int
applyAsInt(T value);
5.
ToLongFunction<T>:
§
Input type can be anything but return type is always
long.
§ Method:
long
applyAsLong(T value);
6.
ToDoubleFunction<T>:
§
Input type can be anything but return type is always
double.
§ Method:
double
applyAsDouble(T value);
7.
IntToLongFunction<T>:
§
Input type must Int and output type must long then we should
use this function.
§ Method:
long
applyAsLong(int
value);
8.
IntToDoubleFunction<T>:
§
Input type must Int and output type must double then we
should use this function.
§ Method:
double
applyAsDouble(int
value);
9.
longToIntFunction<T>:
§
Input type must long and output type must int then we should
use this function.
§ Method:
int
applyAsInt(long
value);
10.
longToDoubleFunction<T>:
§
Input type must long and output type must double then we
should use this function.
§ Method:
double
applyAsDouble(long
value);
11.
doubleToIntFunction<T>:
§
Input type must double and output type must int then we
should use this function.
§ Method:
int
applyAsInt(double
value);
12.
doubleToLongFunction<T>:
§
Input type must double and output type must long then we
should use this function.
§ Method:
long
applyAsLong(double
value);
13.
ToIntBiFunction<T,U>:
§ Method:
int
applyAsInt(T t, U u);
14.
ToLongBiFunction<T,U>:
§ Method:
long
applyAsLong(T t, U u);
15. ToIntBiFunction<T,U>:
§ Method: int applyAsInt(T t, U u);
 
Note: Please click on Image to Purchase the books from Amazon.in |
What is the difference between
IntFunction, ToIntFunction and IntToDoubleFunction?
|
|
IntFunction |
ToIntFunction |
IntToDoubleFunction |
|
1. |
If your input is always int primitive then we should use this
function. |
Input type can be anything but return type is always int. |
Input type must be Int and output type must double then we should
use this function. |
|
2. |
Method: R apply(int
value); |
Method: int
applyAsInt(T value); |
Method: double
applyAsDouble(int value); |
What is method Reference? How will you
implements method reference?
- Method reference can be used to use the existing method with
:: symbol.
- Please refer to the below example.
|
package simplifiedjava.crackedInterview.java8;
@FunctionalInterface
public interface
MyInterface {
public void
display(); } package simplifiedjava.crackedInterview.java8; public class MyClass{
public static void
main(String[] args) {
MyClass myClass = new
MyClass();
MyInterface myInterface = myClass::myMethod;
myInterface.display(); }
public void
myMethod() {
System.out.println("My Method Displayed.");
}
} Output: My Method Displayed. |
Write a program to call static methods
with method reference?
|
package simplifiedjava.crackedInterview.java8; public class Addition {
public static int
add(int num1, int num2) {
return num1 + num2;
} } package simplifiedjava.crackedInterview.java8; import java.util.function.BiFunction; public class AdditionDemo {
public static void
main(String[] args) {
BiFunction<Integer, Integer, Integer> bf
= Addition::add;
int result = bf.apply(100, 200);
System.out.println("Result "+ result);
}
}
Output: Result 300 |
Can you call static method with method
reference?
- Surely, we can call the static method with method
reference.
How does it different from Collection
API?
- Collection can be used for storing and manipulating a group
of data.
- Stream API is only used for processing groups of data.
What are the intermidiate operations?
Can you list out some intermediate operations?
- The operations which return another stream, as a result, are called
intermediate operations.
- Following are the intermediates operations.
|
|
Operation |
Processing way |
|
1. |
filter() |
Returns another stream of elements which satisfy given condition
inside filter. |
|
2. |
map() |
Returns a stream consisting of results after applying given
function to elements of the stream. |
|
3. |
sorted() |
Returns a stream consisting of elements sorted according to natural
sorting order. |
|
4. |
distinct() |
Returns a stream of unique elements. |
|
5. |
skip() |
Returns a stream after skipping first n elemetns. |
|
6. |
limit() |
Returns a stream containing first n elements. |
What are the terminal operations? Can
you list out some terminal operations?
- The operations which return non-stream values like null or collection
object or objects or primitive is called terminal operations.
- Following are the intermediates operations.
|
|
Operation |
Processing way |
|
1. |
collect() |
Returns processed collection object like list, set or map.
|
|
2. |
forEach() |
Perform an action on all elements of stream. |
|
3. |
min() |
Returns lowest element in the stream wrapped in optional
object. |
|
4. |
max() |
Returns highest element in the stream wrapped in optional
object. |
|
5. |
count() |
Returns the number of elements in a stream. |
|
6. |
findFirst() |
Returns the first element of a stream wrapped in Optional
object. |
|
7. |
findAny() |
Returns anyone element randomly from the stream. |
|
8. |
reduce() |
Performs reduction operation on elements of the stream using
initial value and binary operation. |
|
9. |
toArray() |
Returns an array containing elements of a stream. |
|
10. |
anyMatch() |
Returns true if anyone element of a stream matches with given
predicate. |
|
11. |
allMatch() |
Returns true if all elements of a stream matches with given
predicate. |
|
12. |
noneMatch() |
Returns true only if all the elements of a stream doesn’t match
with given predicate. |
- 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
|
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.
My total experience is 10. Initially I had worked on some support
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Services, Cybage Softwares. Fortunately, TCS and Cybage
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