Advance Java Practical Journal

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Chapter 3: Practical on Set Interface

Practical 3.1

Problem Statement

1. Write a Java program to create a Set containing list of items of type String and print the items in the list using Iterator interface. Also print the list in reverse/ backward direction.

Student.java

package com.hiraymca; public class Student {

int rollno; String name;

Double percentage;

public Student(int rollno, String name, Double percentage) {this.rollno = rollno;

this.name = name; this.percentage = percentage;

}

public Student()

{

}

public int getRollno() {return rollno;

}

public void setRollno(int rollno) {this.rollno = rollno;

}

public String getName() {return name;

}

public void setName(String name) {this.name = name;

}

public Double getPercentage() {return percentage;

}

public void setPercentage(Double percentage) {this.percentage = percentage;

}

setExample.java package com.hiraymca;

import java.util.ArrayList; import java.util.Collection;

import java.util.Collections;

import static java.util.Collections.list;

import java.util.Comparator;

import java.util.HashSet;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import java.util.NavigableSet;

import java.util.Scanner;

import java.util.TreeSet;

/**

* @author VIKRAM

public class setExample {

public static void main(String []args)

{

String ans=null;

int rn;

String sn;

double per;

Scanner sc=new Scanner(System.in);

Student s=new Student();

int choice;

//Creating set of students HashSet<Student>studentSet=new HashSet<Student>(); Iterator i;

//Creating Students

{

System.out.println(“Menu”); System.out.println(“1.Adding student”); System.out.println(“2.List all students”); System.out.println(“3.List in reverse direction”); System.out.println(“4.Exit”); System.out.print(“Enter your choice(1..4)”); choice=sc.nextInt();

int flag=0; switch(choice)

{

case 1:

System.out.print(“Enter rollno”); rn=sc.nextInt(); System.out.print(“Enter name”); sn=sc.next();

System.out.print(“Enter percentage”); per=sc.nextDouble();

s=new Student(rn,sn,per); studentSet.add(s);

break;

case 2:

System.out.println(“Rollno”+”\t”+”Name”+”\t”+”Percentage”); studentSet.forEach((s1) -> {System.out.println(s1.getRollno()+”\t”+s1.getName()+”\t”+s1.getPercentage());

});

break; case 3:

Comparator<Student> c=

Comparator.comparing(Student::getRollno,Comparator.reverseOrder()).thenComparing(Student::getNa me,Comparator.reverseOrder());

List<Student>list=new ArrayList<>(studentSet);

list.sort(c);

System.out.println(“Rollno”+”\t”+”Name”+”\t”+”Percentage”); for(Student s2:list)

{

System.out.println(s2.getRollno()+”\t”+s2.getName()+”\t”+s2.getPercentage());

}

break;

case 4:

System.exit(0); break;

}

//adding student in HashSet

System.out.print(“Do you wish to continue(y/n)”); ans=sc.next();

}while(ans.equals(“Y”)||ans.equals(“y”));

//reteriving the student from set

}

Practical 3.2

Problem Statement

1. Write a Java program using Set interface containing list of items and perform the following operations:

1. Add items in the set.

2. Insert items of one set in to other set.

3. Remove items from the set

4. Search the specified item in the set

Student.java

package com.hiraymca;

public class Student {

int rollno; String name;

Double percentage;

public Student(int rollno, String name, Double percentage) {this.rollno = rollno;

this.name = name; this.percentage = percentage;

}

public Student()

{

}

public int getRollno() {return rollno;

}

public void setRollno(int rollno) {this.rollno = rollno;

}

public String getName() {return name;

}

public void setName(String name) {this.name = name;

}

public Double getPercentage() {return percentage;

}

public void setPercentage(Double percentage) {this.percentage = percentage;

}

setExample.java

package com.hiraymca;

import java.util.HashSet; import java.util.Iterator; import java.util.Scanner;

import java.util.function.Predicate;

/**

* @author VIKRAM

public class setExample {

public static void main(String []args)

{

String ans=null; int rn;

String sn; double per;

Scanner sc=new Scanner(System.in); Student s=new Student();

int choice;

//Creating set of students HashSet<Student>studentSet=new HashSet<Student>(); Iterator i;

//Creating Students

{

System.out.println(“Menu”); System.out.println(“1.Adding student”); System.out.println(“2.Removing student”); System.out.println(“3.Search student”); System.out.println(“4.List all students”); System.out.println(“5.Exit”); System.out.print(“Enter your choice(1..4)”); choice=sc.nextInt();

int flag=0; switch(choice)

{

case 1:

System.out.print(“Enter rollno”); rn=sc.nextInt(); System.out.print(“Enter name”); sn=sc.next();

System.out.print(“Enter percentage”); per=sc.nextDouble();

s=new Student(rn,sn,per); studentSet.add(s);

break; case 2:

System.out.print(“Enter roll no to remove element”); rn=sc.nextInt();

i=studentSet.iterator(); while(i.hasNext())

{

s=(Student)i.next(); if(s.getRollno()==rn)

{

i. remove();

System.out.println(“Element is successfully removed”); break;

}

else

{

System.out.println(“Rollno=“+rn);

}

break; case 3:

System.out.println(“Enter the name of student”); sn=sc.next();

i=studentSet.iterator(); if(!i.hasNext())

{

System.out.println(“List is empty”);

}

while(i.hasNext())

{

s=(Student)i.next(); if(s.getName().equals(sn))

{

System.out.println(“Record found”);

System.out.println(s.getRollno()+” “+s.getName()+” “+s.getPercentage()); flag=1;

break;

}

if(flag!=1)

{

System.out.println(“Record not found search again”);

}

break;

case 4:

System.out.println(“Rollno”+”\t”+”Name”+”\t”+”Percentage”); studentSet.forEach((s1) -> {

System.out.println(s1.getRollno()+” “+s1.getName()+” “+s1.getPercentage());

});

break; case 5:

System.exit(0); break;

}

//adding student in HashSet

System.out.print(“Do you wish to continue(y/n)”); ans=sc.next();

}while(ans.equals(“Y”)||ans.equals(“y”));

//reteriving the student from set

}