Why am I getting Index out of bounds?

Question

My code is giving this error:

Index out of bounds

Why is causing this error?

public static void main(String[] args) {
    Map<Integer, String> hashMap = new HashMap<>();
    System.out.println("First input number of your years then name:");
    Scanner sken = new Scanner(System.in);

    while (sken.hasNext() && !sken.equals("exit")) {

        String[] line = sken.nextLine().split(",");
        String name = line[1];
        int howOld = Integer.parseInt(line[0]);
        hashMap.put(howOld, name);
    }
    System.out.println("Input Complete!");

    System.out.println("HeshMap input:");
    System.out.println(hashMap + "\n");  // <-- this line


    Map<Integer, String> treeMap = new TreeMap<>(hashMap);
    System.out.println("Sorted by years:");
    System.out.println(treeMap);

}

Also, I'm sure that the line I marked with comment won't print properly, how is the proper way to print a HashMap?

Answer 1

Reason of Exception

Following line cause of occurrences java.lang.ArrayIndexOutOfBoundsException: 1 because you are trying to sken.nextLine().split(","); I the string entered does not contain , in it you cannot get line[1];

String[] line = sken.nextLine().split(",");

How about refactoring code

Your input should contain , character as per your logic, and exit will be work like this.

while(sken.hasNext())
    {

        String thisLine = sken.nextLine();
        if(thisLine.equals("exit")){
            break;
        }
        String[] line =thisLine.split(",");
        String name= line[1];
        int howOld= Integer.parseInt(line[0]);
        hashMap.put(howOld, name); 
    }

More

May be helpful for you ;)

while(true)
        {
            System.out.println("Please Enter Age:");
            int howOld = sken.nextInt();
            System.out.println("Please Enter Name:");
            String name = sken.next();
            String thisLine = sken.nextLine();
            hashMap.put(howOld, name); 

            System.out.println("Do you want the results (Y/N)?");
            String more= sken.next();
            if(more.equals("N") || more.equals("n")){
                break;
            }
        }

Answer 2

String name= line[1];

This above line is the Culprit , you are accessing index 1 without checking that even if it exist or not .

If your input string does not contain any comma as delimiter , then you'll surely get this Exception , So it's better to check before accessing

if(line.length==1){ // then Access index 

}

Answer 3

Always have a try catch handler check for handling exceptions such as this.

try{
 String[] line = sken.nextLine().split(",");
 String name= line[1];
 int howOld= Integer.parseInt(line[0]);
 hashMap.put(howOld, name); 
} catch (ArrayIndexOutOfBoundsException iobe) {
   // do something here
}