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Object-oriented

 Java is an object-oriented programming language. Everything in Java is an object. Objectoriented means we organize our software as a combination of different types of objects that incorporates both data and behavior. Basic concepts of OOPs are: 1. Object 2. Class 3. Inheritance 4. Polymorphism 5. Abstraction 6. Encapsulation

Architecture-neutral:

 Java is architecture neutral because there are no implementation dependent features, for example, the size of primitive types is fixed. In C programming, int data type occupies 2 bytes of memory for 32-bit architecture and 4 bytes of memory for 64-bit architecture. However, it occupies 4 bytes of memory for both 32 and 64-bit architectures in Java. Portable:Java is portable because it facilitates you to carry the Java bytecode to any platform. It doesn't require any implementation. High-performance: Java is faster than other traditional interpreted programming languages because Java bytecode is "close" to native code. It is still a little bit slower than a compiled language (e.g., C++). Java is an interpreted language that is why it is slower than compiled languages, e.g., C, C++, etc. Distributed:Java is distributed because it facilitates users to create distributed applications in Java. RMI and EJB are used for creating distributed applications. This feature of Java makes us able to access files by calling the methods from any machine on the internet. Multi-threaded:A thread is like a separate program, executing concurrently. We can write Java programs that deal with many tasks at once by defining multiple threads. The main advantage of multi-threading is that it doesn't occupy memory for each thread. It shares a common memory area. Threads are important for multi-media, Web applications, etc. Dynamic:Java is a dynamic language. It supports dynamic loading of classes. It means classes are loaded on demand. It also supports functions from its native languages, i.e., C and C++. Java supports dynamic compilation and automatic memory management (garbage collection)

Abstract class in Java

 A class which is declared as abstract is known as an abstract class. It can have abstract and non-abstract methods. It needs to be extended and its method implemented. It cannot be instantiated.  An abstract class must be declared with an abstract keyword.  It can have abstract and non-abstract methods.  It cannot be instantiated.  It can have constructors and static methods also.  It can have final methods.

MULTITHREADING REALTIME EXAMPLES 

 Background jobs like running application servers like Oracle application server, Web servers like Tomcat etc which will come into action whenever a request comes.  Typing MS Word document while listening to music.  Railway ticket reservation system where multiple customers accessing the server. 

Multithreading in Java 

 Multithreading in java is a process of executing multiple threads simultaneously.  A thread is a lightweight sub-process, the smallest unit of processing. Multiprocessing and multithreading, both are used to achieve multitasking. 

 However, we use multithreading than multiprocessing because threads use a shared memory area. They don't allocate separate memory area so saves memory, and contextswitching between the threads takes less time than process. Java Multithreading is mostly used in games, animation, etc Every thread in Java is created and controlled by the java.lang.Thread class. A thread can be in one of the following states, 1. New born state(New) 2. Ready to run state (Runnable) 3. Running state(Running) 4. Blocked state 5. Dead state 

 JSP Scripting Elements 

 In JSP 

there are three types of scripting elements:  JSP Expressions: It is a small java code which you can include into a JSP page. The syntax is “<%= some java code %>”  JSP Scriptlet: The syntax for a scriptlet is “<% some java code %>”. You can add 1 to many lines of Java code in here.  JSP Declaration: The syntax for declaration is “<%! Variable or method declaration %>”, in here you can declare a variable or a method for use later in the code. JSP Expressions Using the JSP Expression you can compute a small expression, always a single line, and get the result included in the HTML which is returned to the browser. Using the code we have previously written, let’s explore expressions. Eg Code: The time on the server is <%= new java.util.Date() %> Output: The time on the server is Thursday January 21 07:21:43 GMT 2016. Explanation Here the “new java.util.Date()” is processed into the actual date and time shown through HTML on the browser. Let’s explore expressions through a couple of more examples. Examples  In the first example we are going to see an expression for converting a string from lower case to upper case. Here is the code: The Expression: Converting a string to uppercase <%= new String(“Hello World”).toUpperCase() %> Here we are creating a “String” object with “Hello World” set as the value for object. Following that we are calling a Java function “.toUpperCase” to convert the string from lower case to upper case. The HTML: Converting a string to uppercase: HELLO WORLD