How to set path for Java

How to set path for Java

The path is required to be set for executing the java program.

There are two ways to set the path in Java:

1. Temporary
2. Permanent

1) Set the Temporary Path of JDK in Windows

To set the temporary path of JDK, we needs to follow the following steps:

• Open the command prompt
• Copy the path of the JDK/bin directory
• Write in command prompt: set path=copied_path

              For Example: set path=C:\Program Files\Java\jdk1.8.0_16\bin

This path is valid for a particular session. To avoid this better set path in environment variable as permanent path.

2) Set Permanent Path of JDK in Windows

To set the permanent path of JDK, we needs to follow the following steps:

1. Go to MyComputer properties
2. Click on the advanced tab
3. Click on environment variables
4. Click on the new tab of user variables
5. Write the path in the variable name
6. Copy the path of bin folder
7. Paste path of bin folder in the variable value
8. Click on ok button

Setting Java Path in Linux OS

Setting path in Linux OS is the same as setting the path in the Windows OS. 

But, here we use the export tool rather than set. 

Let's see how to set path in Linux OS:

export PATH=$PATH:/home/jdk1.6.01/bin/

First Java Program

First Java Program

To create a simple java program, we needs to create a class that contains one method(the main method). 
And to develop java programs we needs some mandatory components so let's understand the requirement first.


The requirements for Java program

For executing any java program, we needs below mandatory components or steps:

• Install the JDK
• If you don't have installed it, download the JDK and install it.
• Click here to download the JDK
• Set path of the jdk/bin directory.
• Click here to know how to set the Java path.
• If we will not set the jdk path then while compiling the program we will get error like "javac is not recognized as an internal or external command".
• Write the java program
• Compile and run the java program

Lets create our first Java program

  

Step 1: Open Notepad and copy the below code:
   

     class Hello{

        public static void main(String args[]){

          System.out.println("Hello Java");

        }  
     }

Step 2: Save this file as Hello.java.

Step 3: Open command prompt.

Step 4: Go to the directory where the Hello.java has been saved.

Step 5: Compile the code. Type "javac Hello.java" in command prompt and enter.

Step 6: Execute the code. Type "Java Hello" in command prompt and enter.

                Output: Hello Java

Features of Java

Features of Java

The primary objective of Java programming language creation was to make it portable, simple and secure programming language. Apart from this, there are also some excellent features which play an important role in the popularity of this language. The features of Java are also known as java buzzwords.

A list of most important features of Java language is given below.

1. Simple

2. Object-Oriented

3. Portable

4. Platform independent

5. Secured

6. Robust

7. Architecture neutral

8. Interpreted

9. High Performance

10. Multithreaded

11. Distributed

12. Dynamic

Simple

Java is very easy to learn, and its syntax is simple, clean and easy to understand. According to Sun, Java language is a simple programming language because:

Java syntax is based on C++ (so easier for programmers to learn it after C++).

Java has removed many complicated and rarely-used features, for example, explicit pointers, operator overloading, etc.

There is no need to remove unreferenced objects because there is an Automatic Garbage Collection in Java.

Object-oriented

Java is an object-oriented programming language. Everything in Java is an object. Object-oriented means we organize our software as a combination of different types of objects that incorporates both data and behavior.

Object-oriented programming (OOPs) is a methodology that simplifies software development and maintenance by providing some rules.

Basic concepts of OOPs are:

• Object

• Class

• Inheritance

• Polymorphism

• Abstraction

• Encapsulation

Platform Independent

Java is platform independent because it is different from other languages like C, C++, etc. which are compiled into platform specific machines while Java is a write once, run anywhere language. A platform is the hardware or software environment in which a program runs.

There are two types of platforms software-based and hardware-based. Java provides a software-based platform.

The Java platform differs from most other platforms in the sense that it is a software-based platform that runs on the top of other hardware-based platforms. It has two components:

1. Runtime Environment
2. API(Application Programming Interface)

Java code can be run on multiple platforms, for example, Windows, Linux, Sun Solaris, Mac/OS, etc. Java code is compiled by the compiler and converted into bytecode. This bytecode is a platform-independent code because it can be run on multiple platforms, i.e., Write Once and Run Anywhere(WORA).

Secured

Java is best known for its security. With Java, we can develop virus-free systems. Java is secured because:

• No explicit pointer
• Java Programs run inside a virtual machine sandbox
• Classloader: Classloader in Java is a part of the Java Runtime Environment(JRE) which is used to load Java classes into the Java Virtual Machine dynamically. It adds security by separating the package for the classes of the local file system from those that are imported from network sources.
• Bytecode Verifier: It checks the code fragments for illegal code that can violate access right to objects.
• Security Manager: It determines what resources a class can access such as reading and writing to the local disk.

Java language provides these securities by default. Some security can also be provided by an application developer explicitly through SSL, JAAS, Cryptography, etc.

Robust

Robust simply means strong. Java is robust because:

• It uses strong memory management.

• There is a lack of pointers that avoids security problems.

• There is automatic garbage collection in java which runs on the Java Virtual Machine to get rid of objects which are not being used by a Java application anymore.

• There are exception handling and the type checking mechanism in Java. All these points make Java robust.

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).

What is JAVA?

What is JAVA?

Java is a programming language and a platform. Java is a high level, robust, object-oriented and secure programming language.

Java was developed by Sun Microsystems (which is now the subsidiary of Oracle) in the year 1995. James Gosling is known as the father of Java. Before Java, its name was Oak. Since Oak was already a registered company, so James Gosling and his team changed the Oak name to Java.

Platform: Any hardware or software environment in which a program runs, is known as a platform. Since Java has a runtime environment (JRE) and API, it is called a platform.

Java Example: 

class Simple{  

    public static void main(String args[]){  

     System.out.println("Hello Java");  

    }

} 

Types of Java Applications:

There are mainly 4 types of applications that can be created using Java programming:

1) Standalone Application

Standalone applications are also known as desktop applications or window-based applications. These are traditional software that we need to install on every machine. Examples of standalone application are Media player, antivirus, etc. AWT and Swing are used in Java for creating standalone applications.

2) Web Application

An application that runs on the server side and creates a dynamic page is called a web application. Currently, Servlet, JSP, Struts, Spring, Hibernate, JSF, etc. technologies are used for creating web applications in Java.

3) Enterprise Application

An application that is distributed in nature, such as banking applications, etc. is called enterprise application. It has advantages of the high-level security, load balancing, and clustering. In Java, EJB is used for creating enterprise applications.

4) Mobile Application

An application which is created for mobile devices is called a mobile application. Currently, Android and Java ME are used for creating mobile applications.

Java Platforms / Edition

There are 4 platforms or editions of Java:

1) Java SE (Java Standard Edition)

It is a Java programming platform. It includes Java programming APIs such as java.lang, java.io, java.net, java.util, java.sql, java.math etc. It includes core topics like OOPs, String, Regex, Exception, Inner classes, Multithreading, I/O Stream, Networking, AWT, Swing, Reflection, Collection, etc.

2) Java EE (Java Enterprise Edition)

It is an enterprise platform which is mainly used to develop web and enterprise applications. It is built on the top of the Java SE platform. It includes topics like Servlet, JSP, Web Services, EJB, JPA, etc.

3) Java ME (Java Micro Edition)

It is a micro platform which is mainly used to develop mobile applications.

4) JavaFX

It is used to develop rich internet applications. It uses a light-weight user interface API.