question: public static int indexOf ( @ NotNull CharSequence buffer , @ NotNull CharSequence pattern , int fromIndex , final int toIndex ) { final int patternLength = pattern . length ( ) ; int limit = toIndex - patternLength + 1 ; if ( fromIndex < 0 ) { fromIndex = 0 ; } SearchLoop : for ( int i = fromIndex ; i < limit ; i ++ ) { for ( int j = 0 ; j < patternLength ; j ++ ) { if ( pattern . charAt ( j ) != buffer . charAt ( i + j ) ) continue SearchLoop ; } return i ; } return - 1 ; }
target:  Tries to find index of given pattern at the given buffer.