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How to use flatMap() in Java 8 - Stream Example Tutorial

In order to understand the flatMap() method, you first need to understand the map() function of Java 8. The map() function is declared in  the java.util.stream.Stream class and uses to transform one Stream into another, for example, it can convert a stream of integer numbers into another stream of ints where each element is the square of the corresponding element in the source stream. In the map() operation, a function is applied to each element of the source Stream and return values are inserted into a new Stream which is returned to the caller. The key point to note here is that the function used by map() operation returns a single value.

Top 20 Essential Java Interview Questions with Answers for Freshers with 1 to 2 years Experienced

If you are grad looking for an internship position in a company which uses Java, or a fresher, just out from college and looking out for Java development position, then this post is for you. I have attended, taken, and participated in a different level of Java interviews. I can say there is a vast difference between them, which is not surprising because you obviously want to ask different level questions based upon whether the candidate is fresher or experienced. Similarly, the problem at phone interview, written test, and face to face interviews, keeping this in mind, and give you always have a limited amount of time before going for an interview, It's essential to prepare the right set of questions.

java.sql.BatchUpdateException: Error converting data type float to numeric - Java + SQL Server

This error can come if you are inserting or updating a NUMERIC column in Microsoft SQL Server database from a Java Program using executeUpdate()method, I mean executing a  batch update query. It could also happen if you are calling a stored procedure and passing a float value corresponding to a NUMERIC column, and value happened to be out-of-range like generating "Arithmetic overflow error converting numeric to data type numeric" on the SQL Server end. For example, if your column is defined as NUMERIC (6,2) the maximum value it can represent is 9999.99, not 999999.99

How to Compare Two Arrays in Java to check if they are equal - String, Integer Array Example

Hello guys, one of the common Programming, the day-to-date task is to compare two arrays in Java and see if they are equal to each other or not. Of course, you can't compare a String array to an int array, which means two arrays are said to be equal if they are of the same type, has the same length, contains same elements and in the same order. Now, you can write your own method for checking array equality or take advantage of Java's rich Collection API. Similar to what you have seen while printing array values in Java, java.util.Arrays class provides convenient methods for comparing array values.

What is Default or Defender Methods of Java 8 - Tutorial Example

Whenever someone talks about Java 8, the first thing they speak about is lambda expression and how lambda expression has changed the way you use Collections API today. In truth, lambda expression would not be that useful had language not been enhanced to support default methods on Java Interface. Also known as a virtual extension or defender methods, they allow you to declare a non-abstract method inside Java interface. Which means, finally you can add new methods without breaking all classes, which implements a certain interface. This opens a new path for enhancing and evolving existing Collection API to take advantage of lambda expressions. For example, now you can iterate over all elements of Collection in just one line, as opposed to four lines it requires you to do prior to Java 8.

How to get current Day, Month, Year from Date in Java 8 and before? LocalDate vs java.util.Date

In this article, I'll show you how to get the current day, month, year, and dayOfWeek in Java 8 and earlier version like Java 6 and JDK 1.7. Prior to Java 8, you can use the Calendar class to get the various attribute from java.util.Date in Java. The Calendar class provides a get() method which accepts an integer field corresponding to the attribute you want to extract and return the value of the field from given Date, as shown here. You might be wondering, why not use the getMonth() and getYear() method of java.util.Date itself, well, they are deprecated and can be removed in the future version, hence it is not advised to use them.

10 Examples of forEach() method in Java 8

From Java 8 onward, you can iterate over a List or any Collection without using any loop in Java. The new Stream class provides a forEach() method, which can be used to loop over all or selected elements of list and map. forEach() method provides several advantages over traditional for loop e.g. you can execute it in parallel by just using a parallel Stream instead of regular stream. Since you are operating on stream, it also allows you to filter and map elements. Once you are done with filtering and mapping, you can use forEach() to operate over them. You can even use the method reference and lambda expression inside forEach() method, resulting in more clear and concise code.

How to sort HashMap by values in Java 8 using Lambdas and Stream - Example Tutorial

In the past, I have shown you how to sort a HashMap by values in Java, but that was using traditional techniques of pre-Java 8 world. Now the time has changed and Java has evolved into a programming language which can also do functional programming. How can you, a Java Programmer take advantage of that fact to do your day to day task better like how do you sort a Map by values in Java using lambda expressions and Stream API. That's what you are going to learn in this article. It will serve two purposes, first, it will tell you a new way to sort a Map by values in Java, and, second and more important it will introduce you to essential Java 8 features like Lambda Expression and Streams, which every Java Programmer should learn.

Linear Search Algorithm in Java? Example tutorial

In the last article about searching and sorting, you have learned the binary search algorithm and today I'll teach you another fundamental searching algorithm called Linear search. Linear search is nothing but iterating over the array and comparing each element with target element to see if they are equal since we search the array sequential from start to end, this is also known as sequential search or linear search. It is very slow as compared to binary search because you have to compare each element with every other element and definitely not suitable for a large array. It's practically useful only in case of the small array up to 10 to 15 numbers. In the worst case, you need to check all elements to confirm if the target element exists in an array or not.