New command: updateGrade

This command will change the earlier grade with the new one.

its so urgent!!!! thank you

Step 3. At this exercise, the input will NOT be error free. This means that we will test your program with incorrect or unexpected inputs. Hence, you need to check as many cases as you can to provide a robust program. Your outputs should be as follows in case of exception: If the input commands are wrong: "Wrong input." If the student doesn't exist for calc command: "Student not found." For any other case: "Exception." Step 4. Program will quit when the user enters q. Submit all files in your program. You are free at your designs. But you can submit maximum 3 files. Good luck. Expected output will be as follows: (Bold text represents the inputs) Enter command: add 09DEF45678 80 Enter command: add 09DEF45678 90 100 Enter command: add 09DEF45678 70 Enter command: calc 09DEF45678 09DEF45678: 85 Enter command: acc 09XYZ67890 55 Wrong input Enter command: add 111 Wrong input Enter command: calc 09XYZ67891 Student not found. Enter command: Enter command: add 69DEF45678 80 Enter command: add 99DEF45678 90 100 Enter command: add 9DEF45678 70 Enter command: calc 99DEF45678 89DEF45678: 85 Enter command: acc @9XYZ67890 55 Wrong input. Enter command: add 111 Wrong input. Enter command: calc 99XYZ67891 Student not found. Enter command