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General

Vector Class in Java

Vector Class in Java

Vector Class in Java

  • Vector class implements List
  • It uses Array data structure to represent the elements.
  • Vector class is synchronized ( thread safe) unlike ArrayList class.

Various Syntax of Vectors :

Type Syntax
Non Generic Signature Vector obj = new Vector();
Generic Signature Vector <DataType> obj = new Vector<DataType>();
With Initial Capacity Vector obj = new Vector(int initialCapacity);
With Initial Capacity and Increment : Vector obj = new Vector(int initialcapacity, int capacityIncrement );

Note : By default, the capacity of the vector is 10.

Example:

package mypackage;
import java.util.Vector;
public class VectorExample{
public static void main(String[] args) {
Vector<String> vec= new Vector<String>();
vec.add("Happy");
vec.add("For");
vec.add(2, "ever"); //adding “i” in the index 1
System.out.println("*********************************************");
System.out.println("Vector elements are:");
for(String s:vec){ //iterating using for loop
System.out.println(s);
}
System.out.println("The capacity of Vector-->" + vec.capacity());
System.out.println("The Size of Vector before Removal-->" +  vec.size());
System.out.println("vector before Remval:"+ vec);
vec.remove("For");
System.out.println("Vector after removal :" + vec);
System.out.println("The Size of Vector after Removal-->" +  vec.size());
System.out.println("*********************************************");
}
}

Output:

*********************************************

Vector elements are:

Happy

For

ever

The capacity of Vector–>10

The Size of Vector before Removal–>3

vector before Remval:[Happy, For, ever]

Vector after removal :[Happy, ever]

The Size of Vector after Removal–>2

*********************************************

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Methods of Vector Class :

Method Name Description
boolean add(E e) Appends the element e to the end of the list.
void add(int i, E element) Inserts the element e at the specified index ‘i’ in the list.
void addElement(E obj) Inserts the element to the vector and increases the vector size by 1. This method is synchronised.
int capacity() Returns the current capacity of the vector.- default is 10
boolean contains(Object o) Returns true if the list contains the element.
E elementAt(int index) Returns the element at given index.
boolean isEmpty() Returns true if the list has no elements
void ensureCapacity(int minCapacity) Ensures that the specified capacity is maintained. Increases the capacity if needed.
void insertElementAt(Object obj, int index) Inserts the object ‘obj’ in the vector at the specified index
E remove(int index) Removes the element at the specified index in the vector.
boolean remove(Object o) Removes the first occurrence of the object from the vector.
void removeElementAt(int index) Removes the element specified in the given index.
int size() Returns the number of elements in the list.
E set(int index, E element) Replaces the element at the specified index in the vector with the given element.
boolean addAll(Collection<? extends E> c) Appends all of the elements in the specified collection to the end of the vector.
boolean removeAll(Collection<?> c) Removes all the elements that are contained in the specified collection from the vector.

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