daveRanjan

public class AreaFinder{
 
     public static void main(String[] args){
        //This will create an object of circle class
         Shape circle = new Circle();
         //This will create an object of Rectangle class
         Shape rectangle = new Rectangle();

         // Drumbeats ……
         //This should print 78.5

daveRanjan

public class Rectangle extends Shape {
		 private Double length = 5.0;
		 private Double breadth= 10.0;
		// See this annotation @Override, it is telling that this method is from parent
		 // class Shape and is overridden here
		 @Override
		 public Double area(){
		 		return length * breadth;
		 }
 }

daveRanjan

public class Circle extends Shape {
		 private Double radius = 5.0;

		 // See this annotation @Override, it is telling that this method is from parent
		 // class Shape and is overridden here
		 @Override
		 public Double area(){
		 		return 3.14 * radius * radius;
		 }
 }

daveRanjan

public abstract class Shape{
	 public abstract Double area();
 }

daveRanjan

 static String valueOf(boolean b) 
 static String valueOf(char c) 
 static String valueOf(char[] data) 
 static String valueOf(char[] data, int offset, int count) 
 static String valueOf(double d) 
 static String valueOf(float f) 
 static String valueOf(int i) 
 static String valueOf(long l) 
 static String valueOf(Object obj)

daveRanjan

public class Shape{
   //It could be a circle or rectangle or square
   private String type;

   //To calculate area of rectangle
   public Double area(Long length, Long breadth){
    	return (Double) length * breadth;
   }

   //To calculate area of a circle

daveRanjan

public class BadConstructor{
 
  public String param1;
  public int param2;
  public char[] param3;
  public AnotherClass param4;
  public List param5;
  public Set param6;
  
  public BadConstructor(String param1, int param2, char[] param3, AnotherClass param4, List<String> param5, HashSet<String> param6){

daveRanjan

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx" xmlns:sec="http://www.springframework.org/schema/security"
	xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
       http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.1.xsd
       http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.1.xsd"
	default-autowire="byName">

daveRanjan

class Singleton {

  // This is an object of the same class, but give more attention towards
  // private :- This object cannot be accessed from outside, you have use getter (getInstance) method
  // static :-  This object is static as getInstance have to be static (Why?? You'll know) and 
  //            only static variables can be accessed in static methods
    private static Singleton INSTANCE = null;

  // Ofcourse a class is of no use if it does not have any data (So this is the data for which every thread will fight)
    private String criticalData;