Collections

 

SET A
1. Accept ‘n’ integers from the user and store them in a collection. Display them in the sorted order. The collection should not accept duplicate elements. (Use a suitable collection). Search for an particular element using predefined search method in the Collection framework. 

import java.io.*;

import java.util.*;

class Tree

{

    public static void main(String args[])throws IOException

    {

        Scanner sc =new Scanner (System.in);

        int n,i;

        System.out.println("Enter how many numbers :");

        n=sc.nextInt();

        TreeSet ts=new TreeSet();

        for(i=0;i<n;i++)

        {

            int x=sc.nextInt();

            ts.add (new Integer(x));

        }

        System.out.println("Tree set is :"+ts);

        System.out.println("enter element to be search :");

        int y =sc.nextInt();

        int flag=0;

        for(i=0;i<n;i++)

        {

            if(ts.contains(new Integer(y)))

            {

                System.out.println("Element found");

                flag =1 ;

                break;

            }

            else

            flag=0;

        }

        if(flag==0)

        System.out.println("Element not found .");

    }

}

 

2. Construct a linked List containing names of colors: red, blue, yellow and orange. Thenextend your program to do the following:
i. Display the contents of the List using an Iterator;
ii. Display the contents of the List in reverse order using a ListIterator;
iii. Create another list containing pink and green. Insert the elements of this list
between blue and yellow 

import java.util.*;

import java.io.*;

 class Link

{

    public static void main(String args[])

    {

        LinkedList l1=new LinkedList();

        l1.add("Red");

        l1.add("Blue");

        l1.add("Yellow");

        l1.add("Orange");

        System.out.println("Contents of original linked list :"+l1);

       

        System.out.println("Contents of list using iterator : ");      

        Iterator itr=l1.iterator();

        while(itr.hasNext())

        {

            Object ele=itr.next();

            System.out.println(ele+" ");

        }

   

        System.out.println("Contents of list in reverse order : ");

        ListIterator ltr=l1.listIterator();

        while(ltr.hasNext())

        {

            ltr.next();

        }

        while(ltr.hasPrevious())

        {

            Object ele=ltr.previous();

            System.out.println(ele+" ");

        }  

       

        LinkedList l2=new LinkedList();

        l2.add("Pink");

        l2.add("Green");

        l1.add(2,l2);

        System.out.println(" Contents of Linked list after insertion: "+l1);    

    }

}

3. Create a Hash table containing student name and percentage. Display the details of the
hash table. Also search for a specific student and display percentage of that student.

import java.io.*;

import java.util.*;

class Hash

{

    public static void main(String args[])throws IOException

    {

        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

        Hashtable ht= new Hashtable();

        String name=null;

        float per;

        System.out.println("Enter how many records :");

        int n=Integer.parseInt(br.readLine());

        for(int i=0;i<n;i++)

        {

            System.out.println("Enter student name:");

            name=br.readLine();

            System.out.println("Enter student percentage:");

            per=Float.parseFloat(br.readLine());

            ht.put(name,per);

        }

        System.out.println("Hash table contents are :"+ht);

        Enumeration keys=ht.keys();

        Enumeration values=ht.elements();

        while(keys.hasMoreElements())

        {

            System.out.println(keys.nextElement()+"\t"+values.nextElement());

        }

       

        //Search student

        System.out.println("Enter student name for search:");

        String sm=br.readLine();

        boolean ans=ht.containsKey(sm);

        if(ans==true)

        System.out.println("Percentage :"+ht.get(sm));

        else

        System.out.println("Student not found:");

         

    }

}

SET B
1. Create a java application to store city names and their STD codes using an appropriate
collection. The GUI ahould allow the following operations:
i. Add a new city and its code (No duplicates)
ii. Remove a city from the collection
iii. Search for a cityname and display the code

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.util.*;

class city extends JFrame implements ActionListener

{

    JTextField t1,t2,t3;

    JButton b1,b2,b3;

    JTextArea t;

    JPanel p1,p2;

    Hashtable ts;

    city()

    {

    ts=new Hashtable();

    t1=new JTextField(10);

    t2=new JTextField(10);

    t3=new JTextField(10);

    b1=new JButton("Add");

    b2=new JButton("Search");

    b3=new JButton("Remove");

    t=new JTextArea(20,20);

    p1=new JPanel();

    p1.add(t);

    p2= new JPanel();

    p2.setLayout(new GridLayout(2,3));

    p2.add(t1);p2.add(t2);p2.add(b1);

    p2.add(t3);

    p2.add(b2);

    p2.add(b3);

    add(p1);

    add(p2);

    b1.addActionListener(this);

    b2.addActionListener(this);

    b3.addActionListener(this);

    setLayout(new FlowLayout());

    setSize(500,500);

    setVisible(true);

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

    public void actionPerformed(ActionEvent e)

    {

        if(b1==e.getSource())

        {

            String name = t1.getText();

            int code = Integer.parseInt(t2.getText());

            ts.put(name,code);

            Enumeration k=ts.keys();

            Enumeration v=ts.elements();

            String msg="";

            while(k.hasMoreElements())

            {

                msg=msg+k.nextElement()+" = "+v.nextElement()+"\n";

            }

            t.setText(msg);

            t1.setText("");  t2.setText("");

        }

        else if(b2==e.getSource())

        {

            String name = t3.getText();

            if(ts.containsKey(name))

            {

                t.setText(ts.get(name).toStrings());

            }

            else

            JOptionPane.showMessageDialog(null,"City not found ...");

        }

        else if(b3==e.getSource())

        {

            String name = t3.getText();

            if(ts.containsKey(name))

            {

                ts.remove(name);

                JOptionPane.showMessageDialog(null,"City Deleted ...");

            }

            else

            JOptionPane.showMessageDialog(null,"City not found ...");

        }

    }

public static void main(String a[])

{

    new city();

}}