10 Java String interviews Question answers
String interview questions inwards Java is 1 of Integral utilisation of whatever Core Java or J2EE interviews. No 1 tin deny the importance of String in addition to how much it is used inwards whatever Java application irrespective of whether its substance Java desktop application, spider web application, Enterprise application or Mobile application. The string is 1 of the key of Java programming linguistic communication in addition to right agreement of String shape is a must for every Java programmer. What makes String interview questions inwards Java fifty-fifty to a greater extent than interesting is the exceptional condition of String inwards price of features in addition to privileges it has, similar the + operator is sort of overloaded to perform String concatenation despite the fact that Java does non back upwards operator overloading. There is a separate String puddle to shop String literal etc.
In this article nosotros volition closed to oftentimes asked inquiry on String inwards a Java interview which focuses on make of features similar immutability, thread-safety, security, performance, retentivity consumption, mutable counterparts of String e.g. StringBuilder in addition to StringBuffer, comparing String instances inwards Java, equals() vs == banking concern check for String, using String every bit key inwards HashMap, storing String on array in addition to List etc.
1) What is String inwards Java? Is String is information type?
String inwards Java is non a primitive information type similar int, long or double. The string is a shape or inwards to a greater extent than uncomplicated term a user defined type. This is confusing for individual who comes from C background. String is defined inwards java.lang parcel in addition to wrappers its content inwards a graphic symbol array. String provides equals() method to compare 2 String in addition to provides diverse other methods to operate on String similar toUpperCase() to convert String into upper case, replace() to replace String contents, substring() to acquire substring, split() to split long String into multiple String.
2) Why is String finally inwards Java?
The string is finally past times pattern inwards Java, closed to of the points which brand feel why String is finally is Security, optimization in addition to to keep a puddle of String inwards Java. for details on each of this betoken run into Why String is finally inwards Java.
3) What is the divergence betwixt String in addition to StringBuffer inwards Java?
This is in all likelihood the most mutual inquiry on String I receive got seen inwards Java interviews. Though String in addition to StringBuffer are 2 dissimilar shape they are used inwards the context of concatenating 2 Strings, Since String is immutable inwards Java every functioning which changes String produces novel String, which tin hold out avoided past times using StringBuffer. See String vs StringBuffer for to a greater extent than details.
4) What is the divergence inwards String on C in addition to Java?
If y'all receive got mentioned C inwards your resume, hence y'all are probable to facial expression upwards this String interview question. Well, C String in addition to Java String are completely dissimilar to each other, C String is a cypher terminated character array spell String inwards Java is an Object. Also, String is to a greater extent than characteristic rich inwards Java than C.
5) Why char array is meliorate than String for storing password?
This String interview inquiry is debatable in addition to y'all mightiness non concord amongst interviewer but this is every bit good a hazard to demo that how deep in addition to differently y'all tin cry upwards of. One of the reasons which people give Why y'all should shop a password inwards char array over String is related to immutability since it's non possible to erase contents of String but y'all tin erase contents of a char array. See Why char array preferred over String for a password for a consummate discussion.
6) How exercise y'all compare 2 String inwards Java?
This is closed to other mutual String interview inquiry which appears on fresher score interviews. There are multiple ways to compare 2 String similar equals() method, equalsIgnoreCase() etc, You tin every bit good run into 4 ways to compare String inwards Java for to a greater extent than examples. The top dog matter which interviewer checks is that whether candidate mentioned equality operator or non "==", comparing String amongst equality operator is a mutual error which plant inwards closed to instance in addition to doesn't locomote inwards other. adjacent String interview inquiry is follow-up upwards of this.
7) Can nosotros compare String using == operator? What is the risk?
As discussed inwards previous String question, You tin compare String using equality operator but that is non suggested or advised because equality operator is used to compare primitives in addition to equals() method should hold out used to compare objects. As nosotros receive got seen inwards the pitfall of autoboxing inwards Java that how equality operator tin drive a subtle number spell comparing primitive to Object, anyway String is gratis from that number because it doesn't receive got a corresponding primitive type in addition to non participate inwards autoboxing.
Almost all the fourth dimension comparing String agency comparing contents of String i.e. characters in addition to equals() method is used to perform character-based comparison. equals() render truthful if 2 String points to the same object or 2 String has same contents spell == operator returns truthful if 2 String object points to the same object but render faux if 2 dissimilar String object contains same contents. That explains why sometimes it plant in addition to sometimes it doesn't.
In brusk always utilisation equals method inwards Java to banking concern check equality of 2 String object.
8) How does substring method locomote inwards Java?
This is 1 of the tricky Java question relate to String in addition to until y'all are familiar amongst the internals of String class, it's hard to answer. Substring shares same graphic symbol array every bit master String which tin create a retentivity leak if master String is quite large in addition to non required to retain inwards retentivity but unintentionally retained past times substring which is rattling modest inwards size in addition to prevents large array from start claimed during Garbage collection inwards Java.
9) What is String puddle inwards Java?
Another tough Java question asked inwards String interview. String puddle is a exceptional storage expanse inwards Java heap, generally located on PerGen space, to shop String literals similar "ABC". When Java programme creates a novel String using String literal, JVM checks for that String inwards the puddle in addition to if String literal is already introduce inwards the puddle than the same object is returned instead of creating a whole novel object. String puddle banking concern check is solely performed when y'all create String every bit literal, if y'all create String using new() operator, a novel String object volition hold out created fifty-fifty if String amongst the same content is available inwards the pool.
10) What does intern() method exercise inwards Java?
As discussed inwards previous String interview question, String object created past times new() operator is past times default non added inwards String puddle every bit opposed to String literal. The intern method allows putting a String object into a pool.
11) Is string thread-safe inwards Java?
If y'all are familiar amongst the concept of immutability in addition to thread-safety y'all tin easily reply this String interview inquiry inwards Java. Since String is immutable, it is thread-safe in addition to it tin hold out shared betwixt multiple threads without external synchronization.
If y'all are seriously preparing for Java interviews in addition to exercise non desire to acquire out whatever rock unturned, I strongly propose y'all acquire through questions given inwards Java Programming Interview Exposed, 1 of the rare majority which covers all of import topics for Java interviews.
1) Write a Java programme to opposite String inwards Java without using whatever API? (solution)
This agency y'all tin non utilisation StringBuffer's reverse() method or whatever of String utility method, all y'all tin receive got is a graphic symbol array for reversing contents.
2) Write a Program to banking concern check if a String is a palindrome or not? (solution)
For example, a String e.g. "madam" is a palindrome but "book" is non a palindrome. You every bit good demand to solve this inquiry without taking whatever aid from Java String API.
3) Write a Java programme to banking concern check if 2 String are Anagram or not? (solution)
You demand to write method e.g. isAnagram(String first, String second) which volition render truthful if mo String is an anagram of the commencement string. An anagram must comprise the same number of characters in addition to precisely same characters but inwards dissimilar gild e.g. top in addition to pot, or set down forces in addition to mary.
4) Write a method inwards Java to take away whatever graphic symbol from String? (solution)
For example, y'all demand to write method remove(String word, char removeThis), this method should render a String without character, which is asked to remove. y'all tin utilisation indexOf(), substring() and similar methods from String class, but your method must conduct hold corner cases e.g. passing cypher or empty String, String containing simply 1 graphic symbol etc.
5) Write a method to separate a comma separated String inwards Java? (solution)
6) Write Java programme to impress all permutations of a String e.g. passing "ABC" volition impress all permutations similar "BCA", "CBA" etc (solution)
If y'all are hungry for to a greater extent than String based coding question, y'all tin every bit good banking concern check the Cracking the Coding Interview book, a collection of 189 programming questions in addition to solutions from various programming project interviews of reputed tech companies similar Amazon, Google, Facebook, in addition to Microsoft.
That's all close Java String interview inquiry in addition to answers. In Summary, at that spot are a lot of specifics close String which needs to hold out known for anyone who has started Java programming in addition to these String inquiry volition non simply aid to perform meliorate on Java Interviews but every bit good opens the novel door of learning close String. I didn't know much String related concepts until I come upwards across these inquiry which motivated to enquiry in addition to learns to a greater extent than close String inwards Java.
Further Learning
Data Structures in addition to Algorithms: Deep Dive Using Java
How to convert Date to String inwards JavaHow to convert Enum to String inwards Java How to create comma separated String from Collection inwards Java How to convert String to Double inwards Java How to opposite String inwards Java amongst recursion How to format String inwards Java
String interview questions inwards Java is 1 of Integral utilisation of whatever Core Java or J2EE interviews. No 1 tin deny the importance of String in addition to how much it is used inwards whatever Java application irrespective of whether its substance Java desktop application, spider web application, Enterprise application or Mobile application. The string is 1 of the key of Java programming linguistic communication in addition to right agreement of String shape is a must for every Java programmer. What makes String interview questions inwards Java fifty-fifty to a greater extent than interesting is the exceptional condition of String inwards price of features in addition to privileges it has, similar the + operator is sort of overloaded to perform String concatenation despite the fact that Java does non back upwards operator overloading. There is a separate String puddle to shop String literal etc.
In this article nosotros volition closed to oftentimes asked inquiry on String inwards a Java interview which focuses on make of features similar immutability, thread-safety, security, performance, retentivity consumption, mutable counterparts of String e.g. StringBuilder in addition to StringBuffer, comparing String instances inwards Java, equals() vs == banking concern check for String, using String every bit key inwards HashMap, storing String on array in addition to List etc.
Java String Interview Questions in addition to Answers
Core Java interview :1) What is String inwards Java? Is String is information type?
String inwards Java is non a primitive information type similar int, long or double. The string is a shape or inwards to a greater extent than uncomplicated term a user defined type. This is confusing for individual who comes from C background. String is defined inwards java.lang parcel in addition to wrappers its content inwards a graphic symbol array. String provides equals() method to compare 2 String in addition to provides diverse other methods to operate on String similar toUpperCase() to convert String into upper case, replace() to replace String contents, substring() to acquire substring, split() to split long String into multiple String.
2) Why is String finally inwards Java?
The string is finally past times pattern inwards Java, closed to of the points which brand feel why String is finally is Security, optimization in addition to to keep a puddle of String inwards Java. for details on each of this betoken run into Why String is finally inwards Java.
3) What is the divergence betwixt String in addition to StringBuffer inwards Java?
This is in all likelihood the most mutual inquiry on String I receive got seen inwards Java interviews. Though String in addition to StringBuffer are 2 dissimilar shape they are used inwards the context of concatenating 2 Strings, Since String is immutable inwards Java every functioning which changes String produces novel String, which tin hold out avoided past times using StringBuffer. See String vs StringBuffer for to a greater extent than details.
4) What is the divergence inwards String on C in addition to Java?
If y'all receive got mentioned C inwards your resume, hence y'all are probable to facial expression upwards this String interview question. Well, C String in addition to Java String are completely dissimilar to each other, C String is a cypher terminated character array spell String inwards Java is an Object. Also, String is to a greater extent than characteristic rich inwards Java than C.
5) Why char array is meliorate than String for storing password?
This String interview inquiry is debatable in addition to y'all mightiness non concord amongst interviewer but this is every bit good a hazard to demo that how deep in addition to differently y'all tin cry upwards of. One of the reasons which people give Why y'all should shop a password inwards char array over String is related to immutability since it's non possible to erase contents of String but y'all tin erase contents of a char array. See Why char array preferred over String for a password for a consummate discussion.
6) How exercise y'all compare 2 String inwards Java?
This is closed to other mutual String interview inquiry which appears on fresher score interviews. There are multiple ways to compare 2 String similar equals() method, equalsIgnoreCase() etc, You tin every bit good run into 4 ways to compare String inwards Java for to a greater extent than examples. The top dog matter which interviewer checks is that whether candidate mentioned equality operator or non "==", comparing String amongst equality operator is a mutual error which plant inwards closed to instance in addition to doesn't locomote inwards other. adjacent String interview inquiry is follow-up upwards of this.
7) Can nosotros compare String using == operator? What is the risk?
As discussed inwards previous String question, You tin compare String using equality operator but that is non suggested or advised because equality operator is used to compare primitives in addition to equals() method should hold out used to compare objects. As nosotros receive got seen inwards the pitfall of autoboxing inwards Java that how equality operator tin drive a subtle number spell comparing primitive to Object, anyway String is gratis from that number because it doesn't receive got a corresponding primitive type in addition to non participate inwards autoboxing.
Almost all the fourth dimension comparing String agency comparing contents of String i.e. characters in addition to equals() method is used to perform character-based comparison. equals() render truthful if 2 String points to the same object or 2 String has same contents spell == operator returns truthful if 2 String object points to the same object but render faux if 2 dissimilar String object contains same contents. That explains why sometimes it plant in addition to sometimes it doesn't.
In brusk always utilisation equals method inwards Java to banking concern check equality of 2 String object.
8) How does substring method locomote inwards Java?
This is 1 of the tricky Java question relate to String in addition to until y'all are familiar amongst the internals of String class, it's hard to answer. Substring shares same graphic symbol array every bit master String which tin create a retentivity leak if master String is quite large in addition to non required to retain inwards retentivity but unintentionally retained past times substring which is rattling modest inwards size in addition to prevents large array from start claimed during Garbage collection inwards Java.
9) What is String puddle inwards Java?
Another tough Java question asked inwards String interview. String puddle is a exceptional storage expanse inwards Java heap, generally located on PerGen space, to shop String literals similar "ABC". When Java programme creates a novel String using String literal, JVM checks for that String inwards the puddle in addition to if String literal is already introduce inwards the puddle than the same object is returned instead of creating a whole novel object. String puddle banking concern check is solely performed when y'all create String every bit literal, if y'all create String using new() operator, a novel String object volition hold out created fifty-fifty if String amongst the same content is available inwards the pool.
10) What does intern() method exercise inwards Java?
As discussed inwards previous String interview question, String object created past times new() operator is past times default non added inwards String puddle every bit opposed to String literal. The intern method allows putting a String object into a pool.
11) Is string thread-safe inwards Java?
If y'all are familiar amongst the concept of immutability in addition to thread-safety y'all tin easily reply this String interview inquiry inwards Java. Since String is immutable, it is thread-safe in addition to it tin hold out shared betwixt multiple threads without external synchronization.
If y'all are seriously preparing for Java interviews in addition to exercise non desire to acquire out whatever rock unturned, I strongly propose y'all acquire through questions given inwards Java Programming Interview Exposed, 1 of the rare majority which covers all of import topics for Java interviews.
String based Coding Questions
These questions are most based upon Java's implementation of String in addition to you tin solely reply them good if y'all receive got skillful noesis of java.lang.String class. But, String is rattling full general information construction in addition to y'all volition detect it inwards almost all programming in addition to script linguistic communication e.g. C, C++, C#, Python, Perl or Ruby. That's why I am going to portion closed to to a greater extent than String based coding question, which is non Java specific. You tin solve these inquiry inwards whatever programming linguistic communication every bit they are generally logic based programming question.1) Write a Java programme to opposite String inwards Java without using whatever API? (solution)
This agency y'all tin non utilisation StringBuffer's reverse() method or whatever of String utility method, all y'all tin receive got is a graphic symbol array for reversing contents.
2) Write a Program to banking concern check if a String is a palindrome or not? (solution)
For example, a String e.g. "madam" is a palindrome but "book" is non a palindrome. You every bit good demand to solve this inquiry without taking whatever aid from Java String API.
3) Write a Java programme to banking concern check if 2 String are Anagram or not? (solution)
You demand to write method e.g. isAnagram(String first, String second) which volition render truthful if mo String is an anagram of the commencement string. An anagram must comprise the same number of characters in addition to precisely same characters but inwards dissimilar gild e.g. top in addition to pot, or set down forces in addition to mary.
4) Write a method inwards Java to take away whatever graphic symbol from String? (solution)
For example, y'all demand to write method remove(String word, char removeThis), this method should render a String without character, which is asked to remove. y'all tin utilisation indexOf(), substring() and similar methods from String class, but your method must conduct hold corner cases e.g. passing cypher or empty String, String containing simply 1 graphic symbol etc.
5) Write a method to separate a comma separated String inwards Java? (solution)
6) Write Java programme to impress all permutations of a String e.g. passing "ABC" volition impress all permutations similar "BCA", "CBA" etc (solution)
If y'all are hungry for to a greater extent than String based coding question, y'all tin every bit good banking concern check the Cracking the Coding Interview book, a collection of 189 programming questions in addition to solutions from various programming project interviews of reputed tech companies similar Amazon, Google, Facebook, in addition to Microsoft.
That's all close Java String interview inquiry in addition to answers. In Summary, at that spot are a lot of specifics close String which needs to hold out known for anyone who has started Java programming in addition to these String inquiry volition non simply aid to perform meliorate on Java Interviews but every bit good opens the novel door of learning close String. I didn't know much String related concepts until I come upwards across these inquiry which motivated to enquiry in addition to learns to a greater extent than close String inwards Java.
Further Learning
Data Structures in addition to Algorithms: Deep Dive Using Java
How to convert Date to String inwards Java