question: private static String sanitizeString ( String s ) { StringBuilder sb = new StringBuilder ( ) ; for ( int i = 0 ; i < s . length ( ) ; i ++ ) { char ch = s . charAt ( i ) ; if ( ( ( ch >= 'A' ) && ( ch <= 'Z' ) ) || ( ( ch >= 'a' ) && ( ch <= 'z' ) ) || ( ( ch >= '0' ) && ( ch <= '9' ) ) ) sb . append ( ch ) ; else sb . append ( '_' ) ; } return sb . toString ( ) ; }
target:  Remove characters from s that are not safe to use in a filename. 