Core Java - Interview Questions and Answers for 'Filters' | Search Interview Question

Core Java - Interview Questions and Answers for 'Filters' - 9 question(s) found - Order By Newest

Q1. What is a Servlet Filter ?

Ans. It's an object that can intercept http request and response and hence we can take appropriate action on those requests.

There are different types of filters based on Specifications like

Authentication
Logging
Encryption
Tokenizing

etc

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Q2. What is an IO Filter ?

Core Java

Ans. It's an object that reads from one stream and writes to another.

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Q3. What is the difference between filter and filter-mappings xml tag within deployment descriptor ?

Java EE

Ans. filter tag speficies the filter name and respective class for handling filter action whereas filter mapping maps the filter to the url patterns ( specifying the url that needs to be intercepted )

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Q4. What are the advantages of Spring interceptor over Servlet Filters ?

Spring

Ans. Spring Interceptor are Spring beans and hence they can inject other beans and can be used with other Spring frameworks concepts like AOP.

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Q5. Lets say we have a set "set1" with objects of Class A, Class has a non static string called element1, Write a code ( using lambda expression ) to see if there is any object in the set with element1 = "Hello".

Core Java

Ans. set1.stream().filter(p->p.element1.equals("Hello")).findAny().isPreent();

or

set1.stream().map(A::getElement1).anyMatch("Hello"::equals)

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Q6. Write code to get count of every 5 letter word in a string using lambda expression

Core Java

Ans. String str = "I had been saying that he had been there";

Map<String,Long> countWords = Arrays.asList(str.split(" ")).stream().filter(p->p.length() = 5).collect(Collectors.groupingBy(p->p,Collectors.counting()));

System.out.println(countWords);

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Q7. Can we capture the Request body within the interceptor or Filter and perform operations on it ?

Spring

Ans. Yes, But with interceptor it will remove the body from the request and then we will have to explicitly add the attributes to the session to forward it to the handler.

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Q8. Can you explain filter and collectors in java 8 ?

Core Java

Ans. Filters are used to filter object in stream on certail criteria. And collector is used to collect outcome of the stream. Collector is a terminal operation.
List numbers = List.of(1,2,3,4,5,6,7);
List evenNumbers = numbers.stream().filter(n -> n%2==0).collect(Collectors.toList());
The above code will filter out odd numbers and return the list of even number.

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Q9. Can you explain filter and collectors in java 8 ?

Core Java

Ans. Filters are used to filter object in stream on certain criteria.
Collector is used to collect outcome of the stream. Collector is a terminal operation.
List numbers = List.of(1,2,3,4,5,6,7);
List evenNumbers = numbers.stream().filter(n -> n%2==0).collect(Collectors.toList());
The above code will filter out odd numbers and return the list of even number.

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