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Java 8 Stream + FlatMap Example for Beginners

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.

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

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 the Java interface. This 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 the 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 the 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 a more clear and concise code.