int vs Integer

we all are quite familiar with int data type , it is a primitive data type that we have used in different languages like , C C++ Java etc. we have used int for different operations , especially when we start with a program to add two numbers , right ? but we haven’t used “Integer” Data type many times or some of us like me get to know for the very first time. let’s look at a simple program

public class hello{
  
  public static void main(String[] args) {
      int a = 8;
      Integer b = 8;
      
      System.out.println(a);
      System.out.println(b);
  }
}

this program will print 8 both the times , so what’s the difference between these two and which one should I use ? well , it depends on the problem scenario , you can use “int” wherever you want to use , but “int” is a primitive data type and we can’t perform much operation on it where as “Integer” is a wrapper class which provides us some extra functions to help us more while coding , let’s see how

	static void ex1() {
		
		int a[] = {1,3,4,2};
		int b[] = {1,2,5};
		
		int el = 2;
		int flag = 0 ;
		
		for(int i=0;i<3;i++)
		{
			for(int j=0;j<4;j++)
			{
				if(b[i]==a[j])
					flag = flag + 1;
			}
		}
		
		if(flag==3)
			System.out.println("all elements are present");
		else
			System.out.println("1 or more than element is missing");
		
	}

This code will take around O(n^2) time complexity , now let’s try this in some other way

static void ex2() {
		
		Integer a[] = {1,3,4,2};
		Integer b[] = {1,2,5};
		
		int el = 2;
		int flag = 0 ;
		
		for(int i=0;i<3;i++)
		{
			if(Arrays.asList(a).contains(b[i]))
				flag = flag + 1 ;
		}
		if(flag==3)
			System.out.println("all elements are present");
		else
			System.out.println("1 or more than element is missing");
		
	}

now this code is using “Integer” wrapper class , which provides us more options to perform on the data . we have used only one for loop , but I can’t say how this Array.asList().contains() works , so we can’t conclude that time complexity here is O(n) but time must be less than the first code where we have used two for loops So data manipulation becomes more easy with wrapper classes

I tried running both the codes and found that code execution time was almost similar , there was a very minor difference , probably we can ignore it , and we also have to check it for bigger size array like 10K elements and I found that for loop takes less time than Arrays.asList().contains() function

but yes wrapper classes more functionality than primitive data types from converting string to int using Integer.parseInt() and converting back int to string Integer.toString() Wrapper classes gives more power to you :)