Split method throwing an IndexOutOfBounds Exception

Question

I am trying to do a telephone directory using arrays (I have to use arrays). I am trying to write the method for adding new entries. I decided to add a new entry with a line that will be split using the split method into three parts (surname, initials, number) with tabs. When I tried to do the testing for the method I got thrown an IndexOutOfBoundsException.

This is the addEntry method

@Override
public void addEntry(String line) {

    String[] entryLine = line.split("\\t");
    String surname = entryLine[0];
    String initial = entryLine[1];
    String number = entryLine[2];

    Entry entry = new Entry(surname, initial, number);
    count++;

    if (surname == null || initial == null || number == null) {
        throw new IllegalArgumentException("Please fill all the required fields, [surname,initials,number]");
    }
    if (count == entries.length) {
        Entry[] tempEntries = new Entry[2 * count];
        System.arraycopy(entries, 0, tempEntries, 0, count);
        entries = tempEntries;
    } else {
        int size = entries.length;
        for (int i = 0; i < size - 1; i++) {
            for (int j = i + 1; j < entries.length; j++) {
                String one = entry.getSurname();

                if (one.toLowerCase().compareTo(surname.toLowerCase()) > 0) {
                    Entry tempE = entries[i];
                    entries[i] = entries[j];
                    entries[j] = tempE;
                }
            }

        }
    }
}

This is the entry I tried to add:

arrayDirectory.addEntry("Smith  SK  005598");

any particular reason why not use whitespace instead of tabs? — vs97, Mar 24 '19 at 23:25
Could you tell us where the IndexOutOfBoundsException was thrown? — Bill Naylor, Mar 24 '19 at 23:27
@BillNaylor yeah it was thrown here: String initial = entryLine[1]; — Saint Fayson, Mar 24 '19 at 23:29
Possible duplicate of [What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?](https://stackoverflow.com/questions/5554734/what-causes-a-java-lang-arrayindexoutofboundsexception-and-how-do-i-prevent-it) — GBlodgett, Mar 25 '19 at 00:03

score 2 · Accepted Answer · answered Mar 24 '19 at 23:28

2

If the String you're entering is really

Smith  SK  005598

Then your splitting regex

\\t

(tab) cannot work, as the pieces are not separated by tabs.
Instead, you need to use

line.split("\\s+");

As \s+ will match any number of spaces.
The output will correctly result in

[Smith, SK, 005598]

To have each piece separated by a tab, you'd use

Smith\tSK\t005598

Only then your original regex will work.

answered Mar 24 '19 at 23:28

LppEdd

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or if you just want to split on tabs, go: line.split("\t") doubling the '\\' will escape '\' – Bill Naylor Mar 24 '19 at 23:36
@BillNaylor Yes. Also the version he's using now, "\\t", works fine too, but only if pieces are separated using "\t", as I wrote. – LppEdd Mar 24 '19 at 23:38

score 1 · Answer 2 · answered Mar 24 '19 at 23:42

Instead of having the logic:

if (surname == null || initial == null || number == null) 
{
    throw new IllegalArgumentException("Please fill all the required fields, [surname,initials,number]");
}

You should check the split line has length 3:

String[] entryLine = line.split("\\s+");
if (entryLine.length() != 3) 
{
    throw new IllegalArgumentException("...");
}

Because those variables wont be null, the array access will cause IOOB error.

Also you should be putting

 Entry entry = new Entry(surname, initial, number);
    count++;

after the size check (better to put all precondition checks at the start of the method).

Split method throwing an IndexOutOfBounds Exception

2 Answers2