Java Program to Get the Maximum Element From a Vector

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

1. Find An Element
2. Erase An Element
3. 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.Collections.
• Print the max element.

Below is the implementation of the above approach.

// 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 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 elements 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 beginning 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.