ArrayIndexOutOfBoundsException

[fady zohdy]

i found this assignment where i am supposed to get scores input then grade the students according to their scores but i am getting this exception:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at testing.Arrays.main(Arrays.java:23)

public class Arrays {
	 	
	  public static void main(String[] args){
		  
		 Scanner input = new Scanner(System.in); 

                 System.out.println("enter no of students: ");
		 int noOfStudents= input.nextInt();
		 		 	 
		 System.out.println("enter their scores separated by spaces: ");
		 String scoreInput = input.next();
		 
		 String[] individualScores = scoreInput.split(" ");
		 
		 int[] scores = new int[noOfStudents];
		 
		 scores[0] = Integer.parseInt(individualScores[0]);
         scores[1] = Integer.parseInt(individualScores[1]);
		 scores[2] = Integer.parseInt(individualScores[2]);
		 scores[3] = Integer.parseInt(individualScores[3]);
		 
		 for (int x= 0;x<scores.length;x++){
			 if(scores[x]>80){
				 System.out.println("student "+x+" score is "+scores[x]+" and grade is A");
			 }
			 else if(scores[x]>60){
				 System.out.println("student "+x+" score is "+scores[x]+" and grade is B");
			 }
			 else if(scores[x]>40){
				 System.out.println("student "+x+" score is "+scores[x]+" and grade is C");
			 }
			 else{
				 System.out.println("student "+x+" score is "+scores[x]+" and grade is D");
			 }
		 }

		 
	  }
 }

[Henry Wong]

fady zohdy wrote:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at testing.Arrays.main(Arrays.java:23)

Can you show us which is line 23 of your program? We don't know if you show us everything -- actually, you didn't since we know your class is in a package, so, we don't know which is line 23.

Henry

[fady zohdy]

Henry Wong wrote:

Can you show us which is line 23 of your program? We don't know if you show us everything -- actually, you didn't since we know your class is in a package, so, we don't know which is line 23.

Henry

i am really sorry . i modified in the code before submitting it here. here is the right exception

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at testing.Arrays.main(Arrays.java:19)

[Henry Wong]

fady zohdy wrote:
i am really sorry . i modified in the code before submitting it here. here is the right exception

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at testing.Arrays.main(Arrays.java:19)

Well, assuming that this line is close, it would be caused by this line...

scores[1] = Integer.parseInt(individualScores[1]);

which can be caused by two possibilities. However, from the code, we can eliminate one.

It is most likely that your input doesn't split to four components -- in fact, from the error message, it only splits to one element.

Henry

[fady zohdy]

Henry Wong wrote:
Well, assuming that this line is close, it would be caused by this line...

scores[1] = Integer.parseInt(individualScores[1]);

which can be caused by two possibilities. However, from the code, we can eliminate one.

It is most likely that your input doesn't split to four components -- in fact, from the error message, it only splits to one element.

Henry

you are right. this line is the cause and the input does split to one element(the first one).
this is my input separated by blank spaces: 40 80 90 50
how do i split it to four components?
and thanks for the help

[Henry Wong]

fady zohdy wrote:
you are right. this line is the cause and the input does split to one element(the first one).
this is my input separated by blank spaces: 40 80 90 50
how do i split it to four components?
and thanks for the help

Hint: Check the scanner input. It may not be the split() that is the issue.

Henry

[Campbell Ritchie]

It is a misunderstanding of how Scanners work. What you are doing is reading something from the keyboard with next(). That reads a single “token” separated from its successor by “whitespace”. So if you write
40 80 90 50
it reads "40", i.e. a String with a 4 character and a 0 character. Not a number. If you try to split that String with spaces in the split method it splits into a one‑element array. So you can use element 0 but not element 1.

More information to follow in a few minutes.

[Campbell Ritchie]

There is a method called nextLine which you can pass "40 80 90 50" to, but for reasons explained in this post, you will only get that input the second time you call nextLine after nextInt.

But why are you reading a line, splitting it, and then trying to parse each token. There is a simpler way to do it. To follow in a few minutes.

[Campbell Ritchie]

You definitely want 4 marks per student? Why not simply set up a 4‑element array and iterate it with a for loop (not for‑each). Then you can initialise each of the 4 elements with Scanner#nextInt.

[Campbell Ritchie]

If you are entering 4 values from the keyboard you need a 4‑element array to hold those 4 values. You are setting the length of the array to a different amount, to be requested from the keyboard. I shall leave you to decide the best way to sort that problem out.

[fady zohdy]

Campbell Ritchie wrote:If you are entering 4 values from the keyboard you need a 4‑element array to hold those 4 values. You are setting the length of the array to a different amount, to be requested from the keyboard. I shall leave you to decide the best way to sort that problem out.

thanks man. you are awesome.

[Campbell Ritchie]

No, I have just been at this game a lot longer than you. And …


“You're welcome”