Utility Classes Programs
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Transcript of 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);
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2 | U t i l i t y C l a s s e s E x a m p l e s
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 :-
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3 | U t i l i t y C l a s s e s E x a m p l e s
Arrays class:-
import java.util.*;
class ArraysDemo {
public static void main(String[] args) {
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)
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4 | U t i l i t y C l a s s e s E x a m p l e s
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();
System.out.println("Array a and b are equal :
"+Arrays.equals(a,b));
}
}
Output :-
Vector class:-
import java.util.*;
class VectorDemo {
public static void main(String[] args) {
Vector v = new Vector();
System.out.println("Initial Size is : "+v.size());
System.out.println("Initial Capacity is : "+v.capacity());
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5 | U t i l i t y C l a s s e s E x a m p l e s
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 :-
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6 | U t i l i t y C l a s s e s E x a m p l e s
Stack class:-
import java.util.*;
class StackDemo {
public static void main(String[] args) {
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);
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7 | U t i l i t y C l a s s e s E x a m p l e s
System.out.println("Popped value from stack is :"+s.pop());
}
}
Output :-
Hashtable class:-
import java.util.*;
class HashtableDemo {
public static void main(String[] args) {
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));
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8 | U t i l i t y C l a s s e s E x a m p l e s
}
}
}
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.
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9 | U t i l i t y C l a s s e s E x a m p l e s
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
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10 | U t i l i t y C l a s s e s E x a m p l e s
import java.util.*;
class StringTokenizerDemo {
public static void main(String[] args) {
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,":,");
System.out.println("String tokens using st2");
while (st2.hasMoreTokens())
System.out.println(st2.nextToken());
StringTokenizer st3 = new StringTokenizer(str1,":,",true);
System.out.println("String tokens using st3");
while (st3.hasMoreTokens())
System.out.println(st3.nextToken());
}
}
Output:-
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11 | U t i l i t y C l a s s e s E x a m p l e s
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);
}
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12 | U t i l i t y C l a s s e s E x a m p l e s
System.out.println("Bit Patterns in bs1 are : "+bs1);
System.out.println();
System.out.println("Bit Patterns in bs2 are : "+bs2);
System.out.println();
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 :-
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13 | U t i l i t y C l a s s e s E x a m p l e s
Date class:-
import java.util.*;
class DateDemo {
public static void main(String[] args) {
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());
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14 | U t i l i t y C l a s s e s E x a m p l e s
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 :-
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16 | U t i l i t y C l a s s e s E x a m p l e s
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 {
public static void main(String[] args) {
MyTimerTask mtt = new MyTimerTask();
Timer t = new Timer();
t.schedule(mtt,1000,2000);
try
{
Thread.sleep(5000);