indexoutofboundsexception - Null Cipher -- Java -

i'm trying code null cipher school assignment, , have no idea i'm doing wrong.

the cipher supposed obtain char number given in pattern class. if it's "-1", end program , return output. if pattern returns "0", skip word , move on next pattern value. other integer , program should char word in place.

so in example below, pattern {1, 0, 0, 1, 5, -1} , text is: "hello, me you're looking for".

the output should : "hmr"

but i'm getting out of bounds error, , when tweak it, it's not printing correct chars.

the code below, please me.

edit: change runtimeerror disappear, i'm getting incorrect output: "e'[space]"

arraylist<character> text; arraylist<character> output; int outputlen; arraylist<integer> pattern;  public preform() {     text = new arraylist<character>();     output = new arraylist<character>();     pattern = new arraylist<integer>();     {         pattern.add(1);         pattern.add(0);         pattern.add(0);         pattern.add(1);         pattern.add(5);         pattern.add(-1);     } }  public void updatelength() {     outputlen = output.size(); }  public void stringtochar(string input) {     (int = 0;i < input.length();i++)     {         string value = input.substring(i,i+1);         text.add(value.charat(0));     } }  public void printstring () {     (int = 0; < output.size();i++)     {         system.out.println(output.get(i) + ", ");     } }  public arraylist<character> run() {     int nullvalue = 0;     int textval = 0;     (int = 0; < pattern.size(); i++)     {         nullvalue = pattern.get(i);         if (nullvalue == -1)         {             return output;         }         else if (nullvalue == 0)         {             textval = nextword(textval);         }         else         {             textval += nullvalue;             char temp = text.get(textval);             output.add(temp);             textval = nextword(textval);         }     }     return output; }  public int nextword (int starting) {     // go next word     int addval = 0;     do{             starting++;     } while(text.get(starting).equals(' '));     addval += starting;     return addval; }  public static void main (string[] args) {     preform event = new preform();     event.stringtochar("hello, me you're "             + "looking for");     event.run();     event.printstring(); } 

thank you!

for exception: in run have check pattern.size() not test.size. @ line exception.

a similar issue in run compare text size, mean pattern

apart code way complicated, i.e. instead of nextword can use "my string".split(" "); , array of string containing each word. there few other issues, that's figure out (its assignment after all)

edit: main logic issue way use nextword in run. first need adapt nextowrd want (skip until next space , start of next word):

public int nextword (int starting) {     // go next word     do{             starting++;     } while(!text.get(starting).equals(' '));     // skip space     starting++;     return starting; } 

and logic in run correct char needs adapted too:

        else         {             char temp = text.get(textval + nullvalue - 1);             output.add(temp);             textval = nextword(textval);         }