question: public void clusterActivities ( float radius , int minimumPoints , String activityType ) { List < Point > studyAreaPoints = new ArrayList < Point > ( ) ; try { if ( activityType == null ) { MyActivityReader minor = new MyActivityReader ( ) ; List < Point > minorPoints = minor . readActivityPointsToList ( sb . getMinorActivityFilename ( ) , studyArea ) ; studyAreaPoints . addAll ( minorPoints ) ; MyActivityReader major = new MyActivityReader ( ) ; List < Point > majorPoints = major . readActivityPointsToList ( sb . getMajorActivityFilename ( ) , studyArea ) ; studyAreaPoints . addAll ( majorPoints ) ; } else if ( activityType . equalsIgnoreCase ( "minor" ) ) { MyActivityReader minor = new MyActivityReader ( ) ; List < Point > minorPoints = minor . readActivityPointsToList ( sb . getMinorActivityFilename ( ) , studyArea ) ; studyAreaPoints . addAll ( minorPoints ) ; } else if ( activityType . equalsIgnoreCase ( "major" ) ) { MyActivityReader major = new MyActivityReader ( ) ; List < Point > majorPoints = major . readActivityPointsToList ( sb . getMajorActivityFilename ( ) , studyArea ) ; studyAreaPoints . addAll ( majorPoints ) ; } else { log . warn ( "Incorrect activity type provided." ) ; throw new RuntimeException ( "Only `minor', `major' or `null' are acceptable activity types." ) ; } } finally { log . info ( "Read activity file(s) sucessfully." ) ; } this . djc = new DJCluster ( radius , minimumPoints , studyAreaPoints ) ; djc . clusterInput ( ) ; }
target:  This method clusters activities.