question: public void addAttribute ( AttributedCharacterIterator . Attribute attribute , Object value , int start , int end ) { if ( attribute == null ) { throw new NullPointerException ( "attribute == null" ) ; } if ( start < 0 || end > text . length ( ) || start >= end ) { throw new IllegalArgumentException ( ) ; } if ( value == null ) { return ; } List < Range > ranges = attributeMap . get ( attribute ) ; if ( ranges == null ) { ranges = new ArrayList < Range > ( 1 ) ; ranges . add ( new Range ( start , end , value ) ) ; attributeMap . put ( attribute , ranges ) ; return ; } ListIterator < Range > it = ranges . listIterator ( ) ; while ( it . hasNext ( ) ) { Range range = it . next ( ) ; if ( end <= range . start ) { it . previous ( ) ; break ; } else if ( start < range . end || ( start == range . end && value . equals ( range . value ) ) ) { Range r1 = null , r3 ; it . remove ( ) ; r1 = new Range ( range . start , start , range . value ) ; r3 = new Range ( end , range . end , range . value ) ; while ( end > range . end && it . hasNext ( ) ) { range = it . next ( ) ; if ( end <= range . end ) { if ( end > range . start || ( end == range . start && value . equals ( range . value ) ) ) { it . remove ( ) ; r3 = new Range ( end , range . end , range . value ) ; break ; } } else { it . remove ( ) ; } } if ( value . equals ( r1 . value ) ) { if ( value . equals ( r3 . value ) ) { it . add ( new Range ( r1 . start < start ? r1 . start : start , r3 . end > end ? r3 . end : end , r1 . value ) ) ; } else { it . add ( new Range ( r1 . start < start ? r1 . start : start , end , r1 . value ) ) ; if ( r3 . start < r3 . end ) { it . add ( r3 ) ; } } } else { if ( value . equals ( r3 . value ) ) { if ( r1 . start < r1 . end ) { it . add ( r1 ) ; } it . add ( new Range ( start , r3 . end > end ? r3 . end : end , r3 . value ) ) ; } else { if ( r1 . start < r1 . end ) { it . add ( r1 ) ; } it . add ( new Range ( start , end , value ) ) ; if ( r3 . start < r3 . end ) { it . add ( r3 ) ; } } } return ; } } it . add ( new Range ( start , end , value ) ) ; }
target:  Applies a given attribute to the given range of this string.