Prerequisite: Vectors in Java
Why We Use Vector?
Till now, we have learned two ways for declaring either with a fixed size of array or size enter as per the demand of the user according to which array is allocated in memory.
int Array_name[Fixed_size] ; int array_name[variable_size] ;
Both ways we land up wasting memory so in order to properly utilize memory optimization vectors are introduced.
Advantages Of Using Vectors
- Dynamic Size
- Rich Library Functions
- Easy To Know Size
- No Need To Pass Size
- Can be returned from a function
- By default initializes with default values
Rich Library Functions Includes
- Find An Element
- Erase An Element
- Insert An Element
Here, we use rich library functions to get a maximum element.
Note: Arrays are always passed as a pointer in arrays so another parameter you must pass the size of the array but that is not required in the case of vectors.
Syntax :
In the case of Arrays
type function_Name(type arrayName[], type sizeOfArray) ;
In the case of Vectors
type function_Name(vector<type> vectorName) ;
Considering An Example given a vector, the task is to find the maximum element.
Examples:
Input: v1={1,2,3,4,5}
Output: 5
Input: v2={7,50,0,67,98}
Output: 98
Method 1: Using a Predefined Function
- First, we will initialize a vector lets say v, then we will store values in that vector.
- After that, we will call the predefined method called max() defined in class java.util.Collectons.
- Print the max element.
Below is the implementation of the above approach.
Java
// Java Program to find maximum element // in a vector using predefined method import java.io.*; // Importing Vector Class import java.util.Collections; // Importing Vector Class import java.util.Vector; class GFG { // Main Method public static void main(String[] args) { // initializing a Vector Vector<Integer> v = new Vector<Integer>(); // adding values to the Vector v.add(7); v.add(50); v.add(0); v.add(67); v.add(98); // finding the largest element int n = Collections.max(v); // printing the largest element System.out.println( "The maximum value present in Vector is : " + n); } } |
Output :
The maximum value present in Vector is : 98
Worst Case Time Complexity: O(n) where n is the number of elements present in the vector.
Method 2: Comparing each element present in Vector
- First, we will initialize a vector lets say v, then we will store values in that vector.
- Next, we will take a variable, let us say maxNumber and assign the minimum value possible.
- Traverse till the end of vector and compare each element of a vector with maxNumber.
- If the element present in the vector is greater than maxNumber, then update maxNumber to that value.
- Print maxNumber.
Below is the implementation of the above approach.
Java
// Java program to find largest element // present in Vector via comparison import java.io.*; // Importing Vector Class import java.util.Vector; // Importing Iterator Class import java.util.Iterator; class GFG { // Main Method public static void main(String[] args) { // initializing vector of Integer type Vector<Integer> v = new Vector<Integer>(); // Adding eleemnts in vector v.add(1); v.add(2); v.add(3); v.add(4); v.add(5); // Assigning min value possible int maxValue = Integer.MIN_VALUE; // Creating an iterator to traverse through vector // in the begining itr will point to index just // before first element Iterator itr = v.iterator(); // See if there is any next element while (itr.hasNext()) { // Moving iterator to next element int element = (Integer)itr.next(); // Comparing if element is larger than maxValue if (element > maxValue) { // Update maxValue maxValue = element; } } // Print maxVaue System.out.println( "The largest element present in Vector is : " + maxValue); } } |
Output :
The largest element present in Vector is : 5
Time Complexity: O(n) where n is the number of elements present in the vector.
Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready.
