utility classes programs

8/6/2019 Utility Classes Programs

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1 | U t i l i t y C l a s s e s E x a m p l e s

Collections class:-

import java.util.*;

class CollectionsDemo {

public static void main(String[] args) {

ArrayList al = new ArrayList();

al.add(30);

al.add(40);

al.add(10);

al.add(30);

al.add(20);

System.out.println("Initial Contents of List : \n"+al);

Collections.rotate(al,2); // used rotate contents of list by 2indices.

System.out.println("List contents after rotating elements by 2 :\n"+al);

Collections.sort(al); // sorts al in ascending order.System.out.println("Sorting list elements in Ascending order :

\n"+al);

Collections.shuffle(al); // shuffles the elements of al.

System.out.println("After Shuffling the list contents : \n"+al);

Comparator comp = Collections.reverseOrder(); // Obtain areverse order

// comparator.

Collections.sort(al,comp); // sorts al using specifiedcomparator.

System.out.println("Sorting list elements in Descending order :\n"+al);




int i = Collections.binarySearch(al,20,comp); // search’selement 20 in list al

// which uses comparatorcomp.

if(i<0)

System.out.println("Element Not Found");

else

System.out.println("Element 20 Found at location : "+i);

Collections.swap(al,1,3); // exchanges elements of index 1 &3 in al.

System.out.println("List contents After swapping values at 1 and3 : \n"+al);

System.out.println("Max Element in list is :"+Collections.max(al));

System.out.println("Min Element in list is : "+Collections.min(al));

System.out.println("Frequency of element 30 is :"+Collections.frequency(al,30));

}

}

Output :-




Arrays class:-

import java.util.*;

class ArraysDemo {


String[] a = {"CSE","MECH","CIVIL","ECE"};

List l = Arrays.asList(a); // Converting array to list.

System.out.println("Contents of List are :\n "+l);

Arrays.sort(a); // Sorting array.

System.out.println("The array contents after sorting :");

for(String s:a)

System.out.print(s+" ");

System.out.println();

// Performing binary search on array "a" which is sorted in Ascendingorder.

int x = Arrays.binarySearch(a,"CSE");

if(x<0)




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

else

System.out.println("Element found at location"+x);

String[] b = Arrays.copyOf(a,a.length); // Copying array.

System.out.println("The array b contents are :");

for(String s:b)

System.out.print(s+" ");


System.out.println("Array a and b are equal :

"+Arrays.equals(a,b));

}

}

Output :-

Vector class:-

import java.util.*;

class VectorDemo {


Vector v = new Vector();

System.out.println("Initial Size is : "+v.size());

System.out.println("Initial Capacity is : "+v.capacity());




v.addElement("B");

v.addElement("D");

v.addElement("A");

v.addElement("C");

v.addElement("E");

v.addElement("G");

System.out.println("After adding elements \n Vector Size is :"+v.size());

System.out.println("Vector Capacity is : "+v.capacity());

v.addElement("H");

v.addElement("F");

v.addElement("J");

v.addElement("I");

v.addElement("K");

v.addElement("L");

System.out.println("After Adding More Elements");

System.out.println("Vector Size is : "+v.size());

System.out.println("Vector Capacity is : "+v.capacity());

Enumeration e = v.elements();

while(e.hasMoreElements())

System.out.println((String)e.nextElement());

System.out.println("Vector contains \"E\" : "+v.contains("E"));

}

}

Output :-




Stack class:-

import java.util.*;

class StackDemo {


Stack s = new Stack();

System.out.println("Stack contents are : "+s);

System.out.println("Initial Size is : "+s.size());

System.out.println("Initial Capacity is : "+s.capacity());

s.push("A");

s.push("D");

s.push("C");

s.push("B");

System.out.println("After Adding Elements");

System.out.println("Stack contents are : "+s);




System.out.println("Popped value from stack is :"+s.pop());

}

}

Output :-

Hashtable class:-

import java.util.*;

class HashtableDemo {


Hashtable ht = new Hashtable();

ht.put("abc",3434.34);

ht.put("lmn",5656.56);

ht.put("pqr",7878.78);

ht.put("xyz",9191.91);

Set s = ht.keySet();

Iterator itr = s.iterator();

while(itr.hasNext())

{

String key = (String)itr.next();

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




}

}

}

Output :-

Properties class:-

import java.util.*;

import java.io.*;

class PropertiesDemo {

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

Properties pt = new Properties();

FileInputStream fis = new FileInputStream("phonebook.dat");

pt.load(fis);

Set s = pt.stringPropertyNames();

TreeSet ts = new TreeSet(s);

for ( Object name: ts)

{

String number = pt.getProperty((String)name);System.out.println(name+" : "+number);

}

pt.setProperty("Nader","9885098850"); // setting 2 newproperties.




pt.setProperty("Ali","9849098490");

FileOutputStream fos = new FileOutputStream("phonebook.dat");

pt.store(fos,"Telephone Book"); // storing contents of properties

object into file.System.out.println();

fis.close();

fos.flush();

fos.close();

}

}

Output:

Phonebook.dat :-

StringTokenizer class:-

Newly addedentries into




import java.util.*;

class StringTokenizerDemo {


String str1 = "Branch:CSE, Course:BE, College:MJCET.";

StringTokenizer st1 = new StringTokenizer(str1);

System.out.println("String tokens using st1");

while (st1.hasMoreTokens())

System.out.println(st1.nextToken());

StringTokenizer st2 = new StringTokenizer(str1,":,");




StringTokenizer st3 = new StringTokenizer(str1,":,",true);




}

}

Output:-




BitSet class:-

import java.util.*;

class BitSetDemo {

public static void main(String[] args) {BitSet bs1 = new BitSet(16);

BitSet bs2 = new BitSet(16);

for(int i=0;i<16;i++)

{

if(i%2==0)

bs1.set(i);if(i%5==0)

bs2.set(i);

}




System.out.println("Bit Patterns in bs1 are : "+bs1);


System.out.println("Bit Patterns in bs2 are : "+bs2);


bs2.and(bs1);

System.out.println("After AND oper's, Bit Patterns in bs2 are :"+bs2);

bs2.xor(bs1);

System.out.println("After XOR oper's, Bit Patterns in bs2 are :"+bs2);

bs2.or(bs1);

System.out.println("After OR oper's, Bit Patterns in bs2 are :"+bs2);

bs2.clear(2);

System.out.println("After clearing index-2 bit, Bit Patterns in bs2are : "+bs2);

bs2.clear();

System.out.println("After clearing all bits, Bit Patterns in bs2 are :"+bs2);

}

}

Output :-




Date class:-

import java.util.*;

class DateDemo {


Date d1 = new Date();

System.out.println("D1 Details ");

System.out.println(d1);

System.out.println("Time is : "+d1.getTime());

System.out.println("Hours is : "+d1.getHours());System.out.println("Minutes is : "+d1.getMinutes());

System.out.println("Seconds is : "+d1.getSeconds());

System.out.println("Date is : "+d1.getDate());

Date d2 = new Date();

System.out.println("D2 Details ");

System.out.println(d2);

System.out.println("Time is : "+d2.getTime());

System.out.println("Hours is : "+d2.getHours());

System.out.println("Minutes is : "+d2.getMinutes());




System.out.println("Seconds is : "+d2.getSeconds());

System.out.println("Date is : "+d2.getDate());

System.out.println("d1 is an Earlier date :"+d1.before(d2));

System.out.println("d1 is a Later date :"+d1.after(d2));

d1.setHours(14);

d1.setMinutes(34);

d1.setSeconds(20);

d1.setDate(11);

System.out.println("d1 is an Earlier date :"+d1.before(d2));

System.out.println("d1 is a Later date :"+d1.after(d2));

}

}

Output :-




Output :-

Timer and TimerTask class:-

import java.util.*;

class MyTimerTask extends TimerTask {

public void run() {

System.out.println("This code should be executed at some futuretime");

}

}

class TimerDemo {


MyTimerTask mtt = new MyTimerTask();

Timer t = new Timer();

t.schedule(mtt,1000,2000);

try

{

Thread.sleep(5000);




}

catch (InterruptedException e) { e.printStackTrace(); }

t.cancel();

}

}

Output :-

utility classes programs

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