question: static public String escapeTags ( final String input ) { if ( input == null || input . length ( ) == 0 || ( input . indexOf ( '"' ) == - 1 && input . indexOf ( '&' ) == - 1 && input . indexOf ( '<' ) == - 1 && input . indexOf ( '>' ) == - 1 ) ) { return input ; } StringBuilder buf = new StringBuilder ( input . length ( ) + 6 ) ; char ch ; int len = input . length ( ) ; for ( int i = 0 ; i < len ; i ++ ) { ch = input . charAt ( i ) ; if ( ch > '>' ) { buf . append ( ch ) ; } else if ( ch == '<' ) { buf . append ( "&lt;" ) ; } else if ( ch == '>' ) { buf . append ( "&gt;" ) ; } else if ( ch == '&' ) { buf . append ( "&amp;" ) ; } else if ( ch == '"' ) { buf . append ( "&quot;" ) ; } else { buf . append ( ch ) ; } } return buf . toString ( ) ; }
target:  This method takes a string which may contain HTML tags (ie, &lt;b&gt;, &lt;table&gt;, etc) and replaces any '<',  '>' , '&' or '"' characters with respective predefined entity references.