3 Examples of flatMap() of Stream in Java

Hello guys, if you are doing Java development then you must have come across the flatMap() method on Stream and Optional Class. The flatMap() method is extension of map() function as it does both flattening and mapping (or transformation) instead of just transformation done by map() method. I have explained the difference between map() and flatMap() earlier in detail, but just to revise, let's revisit it. If you have a list of String e.g. {"credit", "debit", "master", "visa"} then you can use the map() method to get a list of integer where each value is length of corresponding String e.g. list.stream().map(s -> s.length()) will produce {6, 5, 6, 4}. This is called transformation because you have transformed an stream of String to a Stream of integer.

Top 50 Advanced Java Garbage Collection and Performance Interview Questions and Answers

Hello Java Developers, If you have gone through any Java Developer interview, particularly for a senior developer role then you know that a good knowledge of JVM internals and Garbage collection is important. Even though Java and JVM take care of memory management for you, bad code can still cause memory leaks and performance issues. For example, if you are creating millions of objects in a loop or keeping an un-intended reference of dead objects then you are putting additional strain on the Garbage collector and creating a memory leak in your application. You cannot blame Java and JVM for that and the only way to avoid such errors is to know about how Garbage collection works.

[Solved] How to check if two String are Anagram in Java? Example

Hello guys, if you are preparing for Coding interviews then you already know that String is one of the most popular topics. You will be bound to get some string-based coding problems on interviews. If not, you have come to the right place becuase we'll look at one of the most popular String programming interview questions today, how to check if two given strings are Anagram of each other? Two String is said to be an anagram of each other, if they contain exactly the same characters but in a different order. For example "ARMY" and "MARY" are an anagram of each other because they contain the exact same characters 'A', 'R', 'M' and 'Y'.

How to create a String or int Array in Java? Example Tutorial

There are several ways to create an array in Java, for example, you can declare the array without initializing it, or you can create and initialize the array in the same line. If you want to make an array with values, then you need to first decide which type of array you want to create? e.g., do you want a String array, which can contain String objects like "abc," "def," or do you want to create an int array that contains int values like 10, 20, etc. In Java, you can create an array of any type, including primitives like byte, int, long, and objects like String, Integer, and other user-defined objects. Let's some code to make a new array in Java.

10 Examples of an Array in Java

Along with the String, the array is the most used data structure in Java. In fact, String is also backed by a character array in Java and other programming languages. It's very important for a Java programmer to have good knowledge of array and how to do common things with array e.g. initialization, searching, sorting, printing array in a meaningful way, comparing array, converting an array to String or ArrayList, and doing some advanced slicing and dicing operation with an array in Java. Like my previous tutorials 10 examples of HashMap in Java, I'll show you some practical examples of an array in Java. If you think, any important operation is not included, you can suggest their examples and I'll add them to this list.

How to find 2nd, 3rd or kth element from end in linked list in Java? Example [Solved]

Hello guys, today, I am going to discuss one of the important linked list based coding problems from interviews - how to find the Kth element from the end? This question is also asked as to how do you find the 3rd element from the last of a singly linked list in one pass or write a Java program to find the 5th element from the tail of a given linked list in one iteration. In this article, you will learn the programming technique so that you can solve any variant of this problem, I mean the Kth node from the tail problems and some linked list-based challenges. The difficulty in this question is that you need to solve the problem in one iteration or one pass. This means you cannot traverse the linked list again. I mean you cannot go till the end then traverse back to the Kth element.

Difference between array and Hashtable or HashMap in Java

A couple of days back someone asked me about the difference between an array and a hashtable, though this is a generic data structure and programming question, I'll answer it from both a general programming perspective as well on Java perspective where Hashtable is not just a data structure but also a class from Java Collection API. Even though both array and hashtable data structure are intended for fast search i.e. constant time search operation also known as O(1) search, the fundamental difference between them is that array require an index while hash table requires a key which could be another object.

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