Java - “String index out of range” exception

Question

I wrote this little function just for practice, but an exception (\"String index out of range: 29\") is thrown and I don\'t know why...

(I know this isn\'t the best

Answer 1

a much better implementation (with regex) is simply return y.replaceAll("\\s+"," "); (this even replaces other whitespace)

and StringBuffer.length() is constant time (no slow null termination semantics in java)

and similarly x.charAt(x.length()); will also throw a StringIndexOutOfBoundsException (and not return \0 like you'd expect in C)

for the fixed code:

while ( y.length()>i)//use length from the buffer
{
    if (y.charAt(i) != ' ')
    {
        y.setCharAt(j, y.charAt(i));
        i++;
        j++;
    }
    else
    {
        y.setCharAt(j, y.charAt(i));
        i++;
        j++;
        while (y.charAt(i) == ' ')
            i++;
    }           
}
y.setLength(j);//using setLength to actually set the length

btw a StringBuilder is a faster implementation (no unnecessary synchronization)