收到ArrayIndexOutOfBoundsException但无法弄清原因

Question

this is a university assignment (sample academic report), I thought I was done and going to submit but when I started testing... I keep receiving ArrayIndexOutOfBoundsException on line 60 in main and I cannot see why. I am new to Java but really put a lot of hours into this program. Any help/advice is much appreciated. line 60 = "int credits = Integer.parseInt(input[1]);" //im thinking error is something to due with data types??? im lost.

Course / Grade / Report classes pass data to the main java2pgm1

Answer 1

When you call split it returns you the an array. Here you are splitting using (":") You need to check the length of variable input before accessing it.

    String[] input = course.split(":");
    int credits = Integer.parseInt(input[1]);

The input array may not contain more than 1 value so it fails

Answer 2

The exception will occur when the input from a user does not correspond to the expected format course_number:number_of_credits:grade_received:term_taken . In your case for what input value are you running into this exception? Does it contain a : ?

Suggest that you test the length of the input array before referencing index[n]

Answer 3

String[] input = course.split(":");
int credits = Integer.parseInt(input[1]);
Integer term = Integer.parseInt(input[3]);
Course cObject = new Course(input[0],credits,input[2],input[3]);

The above snippet in your main always assumes that the course String has abc:def:ghi:jkl atleast 3 ":" in it. It is always good practice to handle the error case, when the string doesn't have 3 ":". Modify your code to something like below

String[] input = course.split(":");
if(input.length == 4)
{
    int credits = Integer.parseInt(input[1]);
    Integer term = Integer.parseInt(input[3]);
    Course cObject = new Course(input[0],credits,input[2],input[3]);
}
else
{
    //show some error message to user
}

Answer 4

here size of input array may be 0 or 1, you can check it by input.length . If size of array is less or equal the element you want to get from array then runtime exception ArrayIndexOutOfBoundsException is thrown.