String class

3/18/2019 Overview of Java, Java buzzwords, Data types, variables: Your Guided Course Template
https://canvas.instructure.com/courses/1480238/pages/overview-of-java-java-buzzwords-data-types-variables?module_item_id=21012842 1/5
Overview of Java, Java buzzwords, Data
types, variables
Java is a platform independent, more powerful, secure, high performance, multithreaded programming
language. Here we discuss some points related to Java.
Define byte
Byte code is the set of optimized instructions generated during compilation phase and it is more
powerful than ordinary pointer code.
Define JRE
The Java Runtime Environment (JRE) is part of the Java Development Kit (JDK). It contains a set of
libraries and tools for developing Java application. The Java Runtime Environment provides the minimum
requirements for executing a Java application.
Define JVM
JVM is set of programs developed by sun Micro System and supplied as a part of the JDK for reading
line by line line of byte code and it converts into a native understanding form of operating system. The
Java language is one of the compiled and interpreted programming language.
Garbage Collector
The Garbage Collector is the system Java program which runs in the background along with a regular
Java program to collect un-Referenced (unused) memory space for improving the performance of our
applications.
Note: Java programming does not support destructor concept in place of destructor, we have garbage
collector program.
Define an API
An API (Application Programming Interface) is a collection of packages, a package is the collection of
classes, interfaces and sub-packages. A sub-package is a collection of classes, Interfaces and sub sub
packages etc.
Java programming contains user friendly syntax so that we can develop effective applications. in other
words if any language is providing user friendly syntax, we can develop error free applications.
Definition of JIT
JIT is the set of programs developed by SUN Micro System and added as a part of JVM, to speed up the
interpretation phase.
Features of Java
Features of a language are nothing but the set of services or facilities provided by the language vendors
to the industry programmers. Some important features of java are;
1. Simple
It is simple because of the following factors:

It is free from pointer due to this execution time of application is improved. [Whenever we write a
Java program without pointers then internally it is converted into the equivalent pointer program].
It has Rich set of API (application protocol interface).
It hs Garbage Collector which is always used to collect un-Referenced (unused) Memory location for
improving performance of a Java program.
It contains user friendly syntax for developing any applications.
2. Platform Independent
A program or technology is said to be platform independent if and only if which can run on all available
operating systems with respect to its development and compilation. (Platform represents O.S).
3. Architectural Neutral
Architecture represents processor.
A Language or Technology is said to be Architectural neutral which can run on any available processors
in the real world without considering their development and compilation.

The languages like C, CPP are treated as architectural dependent.
4. Portable
If any language supports platform independent and architectural neutral feature known as portable. The
languages like C, CPP, Pascal are treated as non-portable language. It is a portable language.
According to SUN microsystem.
5. Multithreaded
A flow of control is known as a threa. When any Language executes multiple thread at a time that
language is known as multithreaded e. It is multithreaded.
6. Distributed
Using this language we can create distributed applications. RMI and EJB are used for creating
distributed applications. In distributed application multiple client system depends on multiple server
systems so that even problem occurred in one server will never be reflected on any client system.
7. Networked
It is mainly designed for web based applications, J2EE is used for developing network based
applications.
8. Robust
Simply means of Robust are strong. It is robust or strong Programming Language because of its
capability to handle Run-time Error, automatic garbage collection, the lack of pointer concept, Exception
Handling. All these points make It robust Language.
9. Dynamic
It supports Dynamic memory allocation due to this memory wastage is reduce and improve performance
of the application. The process of allocating the memory space to the input of the program at a run-time
is known as dynamic memory allocation, To programming to allocate memory space by dynamically we

use an operator called 'new' 'new' operator is known as dynamic memory allocation operator.
10. Secure
It is a more secure language compared to other language; In this language, all code is covered in byte
code after compilation which is not readable by human.
11. High performance
It have high performance because of following reasons;
This language uses Bytecode which is faster than ordinary pointer code so Performance of this
language is high.
Garbage collector, collect the unused memory space and improve the performance of the
application.
It has no pointers so that using this language we can develop an application very easily.
It support multithreading, because of this time consuming process can be reduced to executing the
program.
12. Interpreted
It is one of the highly interpreted programming languages.
13. Object Oriented
It supports OOP's concepts because of this it is most secure language, for this topic you can read our
oop's concepts in detail.
Path
Path variable is set for providing path for all Java tools like java, javac, javap, javah, jar, appletviewer. In
Java to run any program we use java tool and for compile Java code use javactool. All these tools are
available in bin folder so we set path upto bin folder.
classpath
classpath variable is set for providing path of all Java classes which is used in our application. All
classes are available in lib/rt.jar so we set classpath upto lib/rt.jar.
Compile and Run Java Program
In the Java programming language, all source code is first written in plain text files and save with
the .java extension. After compilation, .class files are generated by javac compiler. A .class file does not
contain code that is native to your processor; it instead contains bytecodes (it is machine language of the
Java Virtual Machine1 (JVM)).
The java launcher tool then runs your application with an instance of the Java Virtual Machine (JVM).

Steps For compile Java Program
First Save Java program with same as class name with .java extension.
Example: First.java
Compile: javac Filename.java
Example, javac First.java
Note: Here javac is tools or application programs or exe files which is used for Compile the Java
program.
Steps For Run Java Program
For run java program use java tool.
Run by: java Filename
Example: java First
Note: Here java is tools or application programs or exe files which is used for run the Java program.
Example
class First
{
public static void main(String[] args)
{
System.out.println("Hello Java");
System.out.println("My First Java Program");
}
}
Compile and Execute Java Code
To compile: javac First.java To execute: java First
Output
Hello Java My First Java Program

String class

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