public int indexOf (int ch)

Returns the index within this string of the first occurrence of the specified character. If a character with value ch occurs in the character sequence represented by this String object, then the index (in Unicode code units) of the first such occurrence is returned. For values of ch in the range from 0 to 0xFFFF (inclusive), this is the smallest value k such that:

 this.charAt(k) == ch
 
is true. For other values of ch, it is the smallest value k such that:
 this.codePointAt(k) == ch
 
is true. In either case, if no such character occurs in this string, then -1 is returned.

Parameters:
ch    a character (Unicode code point).

Returns:  the index of the first occurrence of the character in the character sequence represented by this object, or -1 if the character does not occur.