What are JSP implicit objects-

There are 9 JSP implicit objects are following -

-out
-request
-response
-config
-application
-page
-pageContext
-session
-exception

and also you can remember this one through "ORRCAPPSE"

JAVA 8 Features

1. Lambda expression − Adds functional processing capability to Java.
2. Method references − Referencing functions by their names instead of invoking them directly. Using functions as parameter.
3. Default method − Interface to have default method implementation.
4. New tools − New compiler tools and utilities are added like ‘jdeps’ to figure out dependencies.
5. Stream API − New stream API to facilitate pipeline processing.
6. Date Time API − Improved date time API.
7. Optional − Emphasis on best practices to handle null values properly.
8. Nashorn, JavaScript Engine − A Java-based engine to execute JavaScript code.

What are the JAVA 5 features-

Java 5 features are following-

1. for-each loop
2. varargs (variable argument)
3. static import
4. Autoboxing and Unboxing
5. Enum
6. Covariant return type
7. Annotation
8. Generics

How avoid duplicate user defined object in HashSet

For avoiding duplicate user defined object we need to implement the hashCode and equals method

import java.util.HashSet;
import java.util.Set;

class Employee

{
    int id;
    String name;
    Employee(int id,String name)

    {
        this.id=id;
        this.name=name;
    }

    public int getId()
    {
        return id;
    }
    public String getName()

    {
        return name;
    }

    public int hashCode()

    {
        System.out.println("In hashcode");
        int hashcode = 0;
        hashcode = id*3; //use any prime number
        hashcode += name.hashCode();
        return hashcode;
    }

   public boolean equals(Object obj)

   {
        System.out.println("In equals");
        if (obj instanceof Employee) 

        {
            Employee e = (Employee) obj;
            return (e.name.equals(this.name) && e.id == this.id);
        }

        else 

        {
            return false;
        }
    }
}

  public class HelloWorld

  {
       public static void main(String []args){
       Employee e1=new Employee(1,"Ramesh");
       Employee e2=new Employee(1,"Ramesh");
       Set<Employee> set=new HashSet<Employee>();
       set.add(e1);
       set.add(e2);
       System.out.println("Size = "+set.size());
   }
}

***

Suppose we want to add object based on name only -

        Employee e1=new Employee(1,"Ramesh");
        Employee e2=new Employee(2,"Ramesh");

Here name is same but id is different so how we will avoid this type of duplicate object based on name -

Only hashCode and equals method need to update-

public int hashCode()

 {
        System.out.println("In hashcode");
        int hashcode = 0;
        // only name hashCode require
        hashcode += name.hashCode();
        return hashcode;
 }

   

   public boolean equals(Object obj)

   {
        System.out.println("In equals");
        if (obj instanceof Employee) 

        {
            Employee e = (Employee) obj;
            return (e.name.equals(this.name)); // no need to compare id
        } 

        else

        {
            return false;
        }
    }