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Java Program to Find Intersection of two Arrays

Java Program to Take Screenshots

import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.*;

class Snap
{
 public static void main(String args[]) throws Exception
 {
  Robot awt_robot = new Robot();
  BufferedImage Entire_Screen = awt_robot.createScreenCapture(new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()));
  ImageIO.write(Entire_Screen, "PNG", new File("Entire_Screen.png"));
 }
}

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Class

• Class is the collection of similar type of objects which have some common properties.
• Class is a concept which is implemented by object.
• Class is a blueprint of java program from which we create object, then object is instance of class.
• We can also say that class is a collection of variables and methods.

Object

• Any real world entity which have physical existence either living or non living is called an object.
• It is a runtime memory area. Object goes to heap.

How to Create an Object?

• In Java object of any class is created using new keyword.
• new keyword reserve the memory for an object in heap and generate an implicit reference id which is stored in a reference variable.

}

Note: Reference variables and local variables goes to stack and methods goes to method area

• In above example total three objects are created. Firstly an object is created using new operator and its reference id is stored in reference variable e1. Then using e1 we call get() and show() methods. After that we are creating two anonymous objects. You can see that we are getting different outputs in three objects.
• Anonymous object is an object without name.
• We can store one reference id into more than one reference variable.

Simple

• Java derives its syntax from C and object oriented features from C++.
• If you are good in C and C++ programming then you can learn Java easily. Hence Java is Simple.

Secure

• Java provides its own execution environment and hence do not allow any malicious program to access other parts of computer.
• Java Virtual Machine (JVM) verifies the code before execution (sandbox security).

 Portable

• Java is platform independent i.e. Write Once and Run Anywhere (WORA).
• When java program is compiled a .class file (bytecode) is created. This .class file can run on any platform (linux, windows, mac). You just need JVM of that platform.

Robust

• Automatic Memory Management
• Automatic Exception Handling

Object-Oriented

• Java is object oriented programming language same as C++.
• It means focus on the data and methods that manipulate that data instead of taking care of procedures.

Multithreaded

• Java supports multithreaded programming.
• It allows you to write programs that do many things simultaneously.

Architecture-Neutral

• Java is machine independent.
• It was made with goal “write once; run anywhere, anytime, forever”.

Interpreted

• Java enables the creation of cross-platform program i.e. bytecode.
• This code can be executed on any platform that has JVM.

High Performance

• Java bytecode can be easily executed on any machine for very high performance by using a just-in-time (JIT) compiler.

Dynamic

• Java programs carry with them substantial amounts of run-time type information that is used to verify and resolve accesses to objects at run time.

Distributed

• Java enables the creation of distributed applications which can be accessed on the internet.

• Load Code
• Verify Code
• Execute Code
• Provide Runtime Environment