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10 Free Java Programing Books for beginners - download, pdf and HTML

Every Java programmer loves free eBooks on Java, don't you? When I shared my collection of top 10 Java programming books, one of my readers asked me to share some free Java books as well. Doing a quick search on the internet reveals lots of free books, resource, and tutorials to learn Java. I have chosen some of the good Java books, which are FREE, available for download or you can read it online in HTML or PDF format. These books are an excellent resource for any Java beginners, as well as an experienced programmer, and since they are free, it makes absolute sense to have a look on this before buying any other book in Java.

QuickSort Algorithm Example in Java using Recursion - Sorting Algorithm Implementation

The Quicksort algorithm is one of the very popular sorting algorithms in programming, often used to sort a large array of numbers. Though there is numerous algorithm available to sort a list of objects, including integer, string and floating point number, quicksort is best for general purpose. It's a divide and conquers algorithm, where we divide the given array with respect to a particular element, known as 'pivot' such that the lower partition of the array are less than the pivot and upper partition elements of the array are higher than the pivot. The Quicksort is also one of the best examples of recursion, a key programming technique to solve Algorithmic problems. This algorithm is naturally recursive because it sorts the large list by dividing into smaller sub-list and then applying the same algorithm on those.

How to Remove an Element from Array in Java with Example

There is no direct way to remove elements from an Array in Java. Though Array in Java objects, it doesn't provide any methods to add(), remove() or search an element in Array. This is the reason Collection classes like ArrayList and HashSet are very popular. Thanks to Apache Commons Utils, You can use there ArrayUtils class to remove an element from array more easily than by doing it yourself. One thing to remember is that Arrays are fixed size in Java, once you create an array you can not change their size, which means removing or deleting an item doesn't reduce the size of the array. This is, in fact, the main difference between Array and ArrayList in Java.

Top 5 Java EE Bad Practices Java Developers should Avoid

Here are some of the bad coding practices you should avoid while working for a Java EE application or Java Web application in general, which runs on a Web Server like Tomcat or Enterprise Server like JBoss, WebLogic, or IBM WebSphere:

1) Calling System.exit() from a Web application
It is never a good idea for a web application to attempt to shut down the application container. A call to System.exit() is probably part of leftover debug code or code imported from a non-J2EE application. You can further read my article "Don't use System.exit() on Java web application" to learn more about.

Difference between first level and second level cache in Hibernate

The main difference between first level and second level cache in Hibernate is that the first level is maintained at the Session level and accessible only to the Session, while the second level cache is maintained at the SessionFactory level and available to all Sessions. This means, you can use the first level cache to store local data, i.e. the data which is needed by the Session, and you can use the second-level cache to store global data, i.e. something which can be shared across sessions. This is also one of the frequently asked Hibernate Interview questions and accessible in both telephonic rounds as well as on face to face interview, in both fresher and experienced level interviews.

How to use Queue Collection in Java? An example Tutorial

The JDK provides an implementation of several data structure in Java collection framework, e.g., ArrayList is a dynamic array, LinkedList represents a linked list, HashMap represents a hash table data structure, and Queue interface represent queue data structure. Btw, If you are not familiar with data structure itself, then you can also see Introduction to Data Structures & Algorithms in Java, an excellent course to start with the essential data structure in Java. The Queue data structure allows you to process elements in the first in first out order, and that's why it is also known as a FIFO data structure. In order to provide first in primary out functionality, it allows you to insert data at one end and delete data from other ends, also known as consuming data. If you need to process objects in the FIFO order, you can use a Queue to store them.

How to write a Generic method in Java

A method is called generic method if you can pass any type of parameter to it and it will function the same e.g. it allows the same logic to be applied to different types. It's known as a type-safe method as well.


1) You can declare Generic methods not only on Generic or parameterized class but also on regular classes which not generic.

2) The type declaration like <T> should come after modifiers like public static but before return type like the void, int, or float. Here is an example of a generic or parameterized method declaration

public static <T> void swap(T a, T b){

}

Eclipse Netbeans Keyboard Shortcut Mapping for Java programmer

If you are a Java developer who has been using Eclipse for Java development, but you need to use Netbeans for your current project due to various reason,, then this article is for you. Whenever we transition between tools, we need the equivalent of one into other. For example, if you are Eclipse power user who is used to Ctrl + Shift + R and Ctrl + Shift + T then as soon as you start using Netbeans, you miss those shortcut. One thing to keep your productivity up is to quickly find the equivalent shortcut in a new tool, e.g., in Netbeans if you are switching from Eclipse or vice-versa. In this article, I am going to share the Netbeans equivalent of 10 useful Eclipse shortcuts for Java developers. You will benefit if you have to use any of these IDEs.

Difference between Correlated Subquery and Self-contained (non-correlated) subquery in SQL

Hello guys, today, I am going to talk about one of the common SQL concepts of subqueries, a query inside another query. There are two types of subqueries in SQL, correlated subquery and self-contained subquery, also known as nested, non-correlated, uncorrelated or simply a subquery. The main difference between them is, self-contained subqueries are independent of the outer query, whereas correlated subquery has a reference to an element from the table in the outer query. In other words, In the case of the nested subquery, both primary and subquery can run independently. But, in the case of the correlated subquery, you can not run them individually because subquery refers to rows from the outer query.

How to make HTTP Request from a Java Program - Example Tutorial

If you are thinking is it possible to send an HTTP request from a Java program and if yes, how to send a simple HTTP GET request in Java, then you have come to the right place. In this article, I'll show you how you can use the HttpURLConnection class from java.net package to send a simple HTTP request in Java. But, first let me answer your first question, is it possible to send HTTP request in Java? Yes, it's possible and you can send any kind of HTTP request e.g. GET, POST, PUT, DELETE, HEAD, or PATCH. The java.net package provides a class called HttpURLConnection, which can be used to send any kind of HTTP or HTTPS request from Java program.