java - What's wrong with my insertion sort? -

i'm trying sort large datafile using insertion-based sorting algorithm, code runs fine output incorrect. i've studied on , on absolutely no avail, can see i've gone wrong?

public void sort(comparable[] items) {     (int = 1; < items.length; i++) {         comparable temp = items[i];         int j = - 1;         while (j >= 0 && items[j].compareto(items[j]) > 0) {             items[j + 1] = items[j];             j = j - 1;         }         items[j] = temp;     } } 

an example datafile have produced is...

2 1 3 5 9 6 7 4 8 

and output should 1,2,3,4... - instead 1 3 5 9 6 7 4 8 8

items[j].compareto(items[j]) should items[j].compareto(temp), otherwise you're comparing item against - need comparing against object want insert.

then items[j] = temp; cause arrayindexoutofboundsexception because, @ end of loop, items[j] smaller temp, or j == -1, need insert @ position after - simplest fix changing items[j+1] = temp;.