error message using .insert on a string

Question

here's the code DNA_seq1.insert(0,j.charAt(x)); DNA_seq2.insert(0,k.charAt(e)); DNA_align.insert(0,"|"); where DNA_seq1, DNA_seq2, and DNA_align are strings, as are j and k

and here's the error:

DNA.java:151: error: array required, but String found
                             DNA_seq1.insert(0,j[x]);
tion [x][e]take the element from the DNA sequence and ins
f the array we are building
                                                    ^
DNA.java:152: error: array required, but String found
                                 DNA_seq2.insert(0,k[e]);
                                                    ^
DNA.java:153: error: cannot find symbol
                                 DNA_align.insert(0,"|");
                                          ^
  symbol:   method insert(int,String)
  location: variable DNA_align of type String

i seriously don't understand why im getting this error. im thinking its something obvious but my mind is kind of burnt at this point, and its just not clicking.

Answer 1

It's hard to tell from your post what's going on. But ...

DNA_align.insert(0,"|");

If DNA_align really is a String, then there's no insert method, as AnubianNoob pointed out. If you're trying to insert | before the first character of the string, then you can just concatenate it, like this:

"|" + DNA_align;

Also, note that strings are immutable in Java; if s is a String, there is no method s.method(whatever) that modifies the contents of s. There are some methods that make changes to the string and return the changed string as a new string, but s's contents will not be modified. So if you were hoping for a method that changed DNA_align by inserting something into it, forget it. You have to reassign DNA_align, like:

DNA_align = "|" + DNA_align;

Answer 2

String doesn't have an insert() method.

Answer 3

Anubian Noob is correct, there is no insert() function. If you want to do this you can do something like:

String str = "Hello ";
str = str.substring(0, 5) + "World" + str.substring(5, str.length());