Module# 04: Arrays Lecture#15: Vector for Arrays

// Example 15.1: Creating vector

// This program illustrates how a vector can be created.

import java.util.*;

class VectorCreateDemo1 {

public static void main(String[] arg) {

Vector v = new Vector(); // Create a vector of default size 10

v.add(1);

v.add(2);

v.add("Debasis");

v.add(3.4);

v.add("Samanta");

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

}

}

// Example 15.2: Creating a vector to store various types of elements

import java.util.*;

public class VectorCreateDemo2 {

public static void main(String args[]) {

// initial size is 3, increment is 2

Vector v = new Vector(3, 2);

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

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

v.addElement(new Integer(1));

v.addElement(new Integer(2));

v.addElement(new Integer(3));

v.addElement(new Integer(4));

System.out.println("Capacity after four additions: " + v.capacity());

v.addElement(new Double(5.45));

System.out.println("Current capacity: " + v.capacity());

v.addElement(new Double(6.08));

v.addElement(new Integer(7));

System.out.println("Current capacity: " + v.capacity());

v.addElement(new Float(9.4));

v.addElement(new Integer(10));

System.out.println("Current capacity: " + v.capacity());

v.addElement(new Integer(11));

v.addElement(new Integer(12));

System.out.println("First element: " + (Integer)v.firstElement());

System.out.println("Last element: " + (Integer)v.lastElement());

if(v.contains(new Integer(3)))

System.out.println("Vector contains 3.");

// Enumerate the elements in the vector.

Enumeration vEnum = v.elements();

System.out.println("\nElements in vector:");

while(vEnum.hasMoreElements())

System.out.print(vEnum.nextElement() + " ");

System.out.println();

}

}

// Example 15.3: Insertion of elements into a vector

/* The following program shows how to insert the specified object as a component in this vector at the specified index. */

import java.util.*;

class VectorInsertionDemo1 {

public static void main(String[] arg) {

Vector vec = new Vector(7);

// use add() method to add elements in the vector

vec.add(1);

vec.add(2);

vec.add(3);

vec.add(4);

vec.add(5);

vec.add(6);

vec.add(7);

// insert 10 at the index 7

vec.insertElementAt(10, 7);

// checking vector

System.out.println(" Vector: " + vec);

}

}

// Example 15.4: Inserting an element into a vector at specific position

// This program illustrates how an element can be inserted at a specified position in vector.

import java.util.*;

class VectorInsertionDemo2 {

public static void main(String[] arg) {

Vector v = new Vector(5); // Create a default vector of size 5

v.add(1, 1);

v.add(2, 2);

v.add(0, "Debasis");

v.add(3, "Samanta");

v.add(4, 3);

v.add(5, 6.9); // Vector will grow automatically

// insert 10 at the index 7

v.insertElementAt(7, 10);

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

}

}

// Example 15.5: Appending a set element into a vector

/* To append all of the elements in the specified Collection at the end of this Vector. */

import java.util.*;

class VectorInsertionDemo3 {

public static void main(String[] arg) {

ArrayList arr = new ArrayList();

arr.add(3);

arr.add(“Oracle");

arr.add(“Java");

arr.add(4);

Vector v = new Vector(); // Creating a default vector

v.addAll(arr); // copying all element of array list into vector

System.out.println("vector v:"+ v); // checking vector v

}

}

// Example 15.6: Deletion of elements

// To remove all of the elements from a vector.

import java.util.*;

class VectorDeletionDemo1 {

public static void main(String[] arg) {

Vector v = new Vector(); // The initial size of the vector is 10

v.add(0, 1);

v.add(1, 2);

v.add(2, “IIT");

v.add(3, “Kharagpur");

v.add(4, 3);

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

v.clear(); // Clearing the vector

System.out.println(“After clearing: "+ v); // checking vector

}

}

// Example 15.7: Deletion the first and last element from a vector

/* To remove an element at a specified location. It also illustrates the removal of of a specific element. */

import java.util.*;

class VectorDeletionDemo2 {

public static void main(String[] arg) {

Vector v = new Vector(); // Create a vector of (default) capacity 10

v.add(1);

v.add(2);

v.add(“India");

v.add(“Japan");

v.add(4);

v.removeElementAt(0); // Removing the element at 0, if it occurs

System.out.println(“After removal: "+ v); // Checking vector

v.removeElement(“Japan”);

System.out.println(“After removal: "+ v); // Checking vector

}

}

// Example 15.8: Deletion of common element from a vector

/* The following program shows how to retain only the elements in this Vector that are contained in the specified Collection. */

import java.util.*;

class VectorDeletionDemo3 {

public static void main(String[] arg)

{

Vector vec = new Vector(7);

Vector vecRetain = new Vector(4);

// use add() method to add elements in the vector

vec.add(1);

vec.add(2);

vec.add(3);

vec.add(4);

vec.add(5);

vec.add(6);

vec.add(7);

// This elements will be retained

vecRetain.add(5);

vecRetain.add(3);

vecRetain.add(2);

System.out.println("Calling retainAll()");

vec.retainAll(vecRetain);

// Let us print all the elements available in vector

System.out.println("Numbers after removal :- ");

Iterator itr = vec.iterator();

while (itr.hasNext()) {

System.out.println(itr.next());

}

}

}

// Example 15.9: Searching an element

/* The following program shows to check if a specific element is present in a vector or not. */

import java.util.*;

class VectorSearchDemo1 {

public static void main(String[] arg) {

// create default vector

Vector v = new Vector();

v.add(1);

v.add(2);

v.add(“C++");

v.add(“Python");

v.add(3);

// check whether vector contains "Java"

if (v.contains("Java"))

System.out.println("The element exists");

else

System.out.println("The element does notexist");

}

}

// Example 15.10: Searching a specific item at a specific position

/* The following program shows how to return the index of the last occurrence of the specified element in this vector, or -1 if this vector does not contain the element. */

import java.util.*;

class VectorSearchDemo2 {

public static void main(String[] arg) {

// create default vector of capacity 10

Vector v = new Vector();

v.add(1);

v.add(2);

v.add("Oracle");

v.add(2);

v.add("Java");

v.add(4);

// Checking last occurrence of 2

System.out.println("last occurrence of 2 is: " + v.lastIndexOf(2));

}

}

// Example 15.11: Replacement after Searching

/* The following program shows how to set the component at the specified index of this vector to be the specified object. */

import java.util.*;

class VectorUpdateDemo {

public static void main(String[] arg)

{

// Create default vector of capacity 10

Vector v = new Vector();

v.add(1);

v.add(2);

v.add("Mother");

v.add("Merry");

v.add(4);

// Set 4 at the place of 2

v.setElementAt(4, 1);

System.out.println("vector: " + v);

}

}

// Example 15.12: Cloning a vector

// This program duplicates a vector.

import java.util.*;

class VectorCloningDemo {

public static void main(String[] arg) {

Vector v = new Vector();

Vector v_clone = new Vector();

v.add(0, 1);

v.add(1, 2);

v.add(2, "Oracle");

v.add(3, "Java");

v.add(4, 3);

v_clone = (Vector)v.clone();

System.out.println("Clone of v: "+ v_clone);

}

}

// Example 15.13: Copying a vector into a collection

/* The following program shows how to copy the components of this vector into the specified array. */

import java.util.*;

class VectorCopyDemo {

public static void main(String[] arg) {

Vector vec = new Vector(7);

// Use add() method to add elements in the vector

vec.add(1);

vec.add(2);

vec.add(3);

vec.add(4);

vec.add(5);

vec.add(6);

vec.add(7);

Integer[] arr = new Integer[7];

// Copy a vector into array arr

vec.copyInto(arr);

System.out.println("elements in array arr: ");

for (Integer num : arr) {

System.out.println(num);

}

}

}

// Example 15.14: Equality checking of two collections

/* The following program shows how to compare the specified Object with this Vector for equality.. */

import java.util.*;

class VectorCheckDemo {

public static void main(String[] arg) {

// Create default vector of capacity 10

Vector v = new Vector();

v.add(1);

v.add(2);

v.add("Oracle");

v.add("Java");

v.add(4);

// Second vector

Vector v_2nd = new Vector();

v_2nd.add(1);

v_2nd.add(2);

v_2nd.add("Java");

v_2nd.add("Oracle");

v_2nd.add(4);

if (v.equals(v_2nd))

System.out.println("both vectors are equal");

}

}

// Example 15.15: String representation of a vector

/* The following program shows how the toString() method is used to return a string representation of this Vector, containing the String representation of each element. */

import java.util.*;

class VectorStringDemo {

public static void main(String[] arg) {

// create default vector of capacity 10

Vector v = new Vector();

v.add(1);

v.add(2);

v.add(”Debasis");

v.add(”Samanta");

v.add(4);

// string equivalent of vector

System.out.println(" String equivalent of vector: " + v.toString());

}

}

// Example 15.16: Hashcode representation of a vector

/* The following program shows how to return the hash code value for this Vector. */

import java.util.*;

class VectorHashcodeDemo {

public static void main(String[] arg)

{

Vector vec = new Vector(7);

// use add() method to add elements in the vector

vec.add(1);

vec.add(2);

vec.add(3);

vec.add(4);

vec.add(5);

vec.add(6);

vec.add(7);

// checking hash code

System.out.println("Hash code: " + vec.hashCode());

}

}