Java Program to Read a Grade & Display the Equivalent Description

Problem Statement: Numbers on a scale of 1 to 100 are randomly given the grade as the input from the user and then match the input grade of the user against the given cases to generate the desired output.

Real life Example

Consider a number on a scale of 1 to 100 are written on a piece of paper slips. Now person starts picking slips one by one and starts organizing them in such a manner that he starts putting slips in 10 different boxes prior deciding making 10 different pots in such a manner slips numbering 1-10 in ‘pot A’, 11-20 in ‘pot B’ and so on till labeling and inserting slips till all the slips are organized in labeled pots. He did this in order to easily figure out numbers written on slips. 

So in technical terms In these ways machine get

• Take input from the user
• Match the grade using equal to the operator (==)
• Generate the equivalent description as the output

There are several methods starting from brute force(naive) to most optimal. Few are discussed below :

1.  Using the If-Else Method
2. Switch case Method

The grades are assigned using the following 

Approach 1: If-Else Statement

Below is the implementation of the above approach

Java

// Java Program to Read Grade & Displaying Equivalent Desc

// Importing Classes/Files
import java.util.*;

public class GFG {

    // Main Driver Method
    public static void main(String[] args)
    {

        // User is supposed to enter grade among them
        System.out.println(
            "Enter Grade varying from S,A,B,C,D");
        String grade = "A";

        // Checking whether grade == "S" or not
        if (grade == "S") {
            System.out.println(
                "Student has scored between 90 to 100");
        }
        // Checking whether grade == "A" or not
        else if (grade == "A") {
            System.out.println(
                "Student has scored between 80 to 90");
        }
        // Checking whether grade == "B" or not
        else if (grade == "B") {
            System.out.println(
                "Student has scored between 70 to 80");
        }
        // Checking whether grade == "C" or not
        else if (grade == "C") {
            System.out.println(
                "Student has scored between 60 to 70");
        }
        // Checking whether grade == "D" or not
        else if (grade == "D") {
            System.out.println(
                "Student has scored between 50 to 60");
        }
        else {

            // Printing message-user pressed some other key
            System.out.println(
                "The grade you entered is not valid!");
        }
    }
}

Output

Enter Grade varying from S,A,B,C,D
Student has scored between 80 to 90

Approach 2: Switch Case

Below is the implementation of the above approach 

Java

// Java Program to Read a Grade & Display the Equivalent

// Importing Classes/Files
import java.util.*;

public class GFG {

    //  Main driver method
    public static void main(String args[])
    {

        // Random grade taken for consideration
        String grade = "W";

        // Using Switch-Case.
        switch (grade) {
            // Checking whether grade == "S" or not.

        case "S":
            System.out.println(
                "Student has scored between 90 to 100");
            break;

            // Checking whether grade == "A" or not.
        case "A":
            System.out.println(
                "Student has scored between 80 to 90");
            break;

            // Checking whether grade == "B" or not.
        case "B":
            System.out.println(
                "Student has scored between 70 to 80");
            break;

            // Checking whether grade == "C" or not.
        case "C":
            System.out.println(
                "Student has scored between 60 to 70");
            break;

            // Checking whether grade == "D" or not.
        case "D":
            System.out.println(
                "Student has scored between 50 to 60");
            break;

        default:
            System.out.println(
                "The grade you entered is not valid!");
        }
    }
}

Output

The grade you entered is not valid!

Time complexity: O(1) because constant operations are done

Auxiliary space: O(1)