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Top 21 String Programming and Coding Interview Questions With Solutions

In this article, I am going to share 21 of the most common String-based Programming and Coding interview questions from Java developer interviews. These questions require you to write code to solve the problem and they are different from traditional Java String questions like how substring method works in Java or when to use the intern() method of String in Java? Since coding and problem solving are an important part of any programming job interview, it's imperative that you know how to solve them in time and on a pressure situation, which comes only after doing practice with the right set of questions. Since these questions are already tried and tested and appeared in many interviews, they will provide you the experience you need to crack your coding interview.

Difference between POST and GET Request in HTTP Protocol

HTTP Protocol supports many methods to retrieve data from the server or perform any operation on the server, e.g. upload data, delete the file, etc. In total, the HTTP protocol supports the following methods, e.g. GET, POST, PUT, DELETE, HEAD, DELETE, OPTIONS, and TRACE, and HTTP 1.1 reserves technique called CONNECT for future use.  GET, and POST is two of the most common HTTP methods you would hear or work on the web. Though both can be used to send and receive data from client to server, there are some crucial differences between the GET and POST in HTTP, which will help you to understand when you should use GET vs. POST while writing your client and server application.

10 Examples to Format and Parse Date Time in Java 8 using LocalDateTime and DateTimeFormatter

Parsing and formatting dates are other essential topics while working with date and time in Java. Even though old Date API had SimpleDateFormat and DateFormate class to support formatting of date and parsing texts, they were not simple, or should I say there were just simple in writing wrong code. You might know that SimpleDateFormat was not thread-safe and quite heavy to be used as a local variable. Thankfully, this has been sorted now with a new LocalDateTime class and DateTimeFormatter class, which has several inbuilt formatter, like BASIC_ISO_DATE format, which prints dates in yyyyMMdd format, like 20160616 and ISO_DATE which prints date as yyyy-MM-dd, like 2016-06-16. It has several useful formats to represent popular date formats around the world, like the date format used in the USA is different from than date format used in the UK and India.

What is double colon (::) operator in Java 8 - Example

The double colon (::) operator is known as the method reference in Java 8. Method references are expressions which have the same treatment as a lambda expression, but instead of providing a lambda body, they refer to an existing method by name. For example, to print all elements of the list, you can use the forEach() method as follows

list.stream.forEach( s-> System.out.println(s));

but here you can replace lambda expression with method reference to improve readability as shown below:

list.stream.forEach( System.out::println);

You can use method reference or double colon operator to refer a static method, an instance method, or a constructor.

3 ways to find Repeating number in given array in Java?

Problem: You have given an int array that contains duplicate or repeating elements like numbers. You need to find all those repeating numbers from a given array. Remember, the array may contain 1, 2 or multiple duplicates. You need to print all of them. For example, if the given array is {1, 2, 3, 4, 5, 6, 1} then your program should print 1. Similarly, if the given array is {3, 3, 2, 2, 4} then your solution should return 2 and 3, the order is not important as long as you can identify all the repeating elements.

When to use PUT or POST in a RESTful Web Service?

One of the most common confusion among web developers is the choice of PUT or POST HTTP method for creating or updating a resource while developing RESTful Web Services. Since both can be used to submit data, you can use either POST or PUT to create or update a resource. Many web developers want to use PUT for creating a resource on the server because it's idempotent. No matter how many times you call the PUT, the state of the resource will not jeopardize. Since the possibility of re-submission is real on a slow network, using PUT to create resource makes it easy, as you don't need to worry about user clicking the submit button multiple times.

How to remove duplicates from Stream in Java 8 - Stream.distinct() Example

You can use the Stream.distinct() method to remove duplicates from a Stream in Java 8 and beyond. The distinct() method behaves like a distinct clause of SQL, which eliminates duplicate rows from the result set. The distinct() is also a standard method, which means it will return a new Stream without duplicates, which can be used for further processing. Like other methods of Stream class, like map() or filter(), distinct() is also lazy, and it will not remove duplicate elements until you call a terminal method on Stream.  The actual processing of Stream pipeline starts only after calling terminal methods like collect() or forEach().

How to Implement a Power Function in Java - Coding Interview Question

Even though the Java library has a power function, Math.pow(), to calculate the power of a given number in Java, it's a regular programming exercise for Java programmers to implement a power function. If you have used the Math class, then you know that the java.lang.Math.pow(double a, double b) returns the value of the first number raised to the power of the second number and you need to do the same. In other words, you need to write a Java function to calculate the power of integer numbers for simplicity. The original method accepts a binary value, but you are allowed to use just integer, but beware that power function may overflow.

10 Examples of Stream in Java 8 - count + filter + map + distinct + collect

The Java 8 release of Java Programming language was a game-changer version. It not only provided some useful method but totally changed the way you write programs in Java. The most significant change it brings in the mindset of Java developers was to think functional and supported that by providing critical features like lambda expression and Stream API, which takes advantage of parallel processing and functional operations like filter, map, flatMap, etc. Since then, a lot of Java developers are trying their hands to learn those significant changes like lambda expression, method reference, new Date and Time classes, and, more importantly, Stream API for bulk data operations.

13 Free Java 8 Certification Sample Questions - OCAJP8 and OCPJP8 - 1Z0-808 and 1Z09 dumps

Hello guys, Java SE 11 certifications are already out but not many people are going for it because of difficulty level. If you want to become a certified Java developer then Java SE 8 is still the best possible option. If you are preparing for Oracle Java SE 8 Certifications, like OCAJP8 and OCJP8, also known as exam 1Z0-808 and 1Z0-809 and looking for some free practice tests, then you have come to the right place. In this article, I am going to share some of the best OCAJP 8 and OCPJP 8 mock tests available for free of cost online, so that you can check your speed and accuracy before the real exam. These tests are not just useful for Oracle's Java OCA and OCP certification but also for upgrade exams like OCJP 8 upgrade exams with code 1Z0-810 and 1Z0-813, upgrade to Java SE 8 from Java 6 and prior version.

5 Difference between an array and linked list in Java

The difference between an array and linked list is one of the frequently asked data structure and algorithm interview question and you might have seen it before on your telephonic or face-to-face interview. It is also a very popular question during practical exams in Computer Science degree courses e.g. B.E. and B.Tech. It's very simple and easy to answer but you just can't afford to miss this question in an interview. Both array and linked list are two of the most popular and fundamental data structure in Computer Science and Programming, and Java supports both of them. One of the traits of a good programmer is extensive knowledge of data structure and algorithm and that's why it's very important for you to learn the difference between array and linked list data structure and understand when to use an array over a linked list and vice-versa.

How to reverse a singly linked list in Java without recursion? Iterative Solution

Hello guys, reverse a linked list is a common coding problem from Programming Job interviews and I am sure you have seen this in your career, if you are not, maybe you are a fresher and you will going to find about this very soon in your next technical interview. In the last article, I have shown you how to use recursion to reverse a linked list and today, I'll show you how to reverse a singly linked list in Java without recursion. A singly linked list, also known as just linked list is a collection of nodes which can only be traversed in one direction like in the forward direction from head to tail. Each node in the linked list contains two things, a data and a pointer to the next node in the list.