src/main/java/seedu/planner/model/ModelManager.java
private void addDayMapping(Activity act, Day day) {
        if (activityDayMap.containsKey(act)) {
            activityDayMap.get(act).add(day);
        } else {
            activityDayMap.put(act, new ArrayList<>(Arrays.asList(day)));
        }
    }
/**
     * Creates a mapping between an {@code Activity} and the {@code Day} containing it.
     */
Creates a mapping between an  Activity and the  Day containing it.
Creates a mapping between an Activity and the Day containing it .
private void addDayMapping(Activity act, Day day) {
        if (activityDayMap.containsKey(act)) {
            activityDayMap.get(act).add(day);
        } else {
            activityDayMap.put(act, new ArrayList<>(Arrays.asList(day)));
        }
    }
private void addDayMapping ( Activity act , Day day ) { if ( activityDayMap . containsKey ( act ) ) { activityDayMap . get ( act ) . add ( day ) ; } else { activityDayMap . put ( act , new ArrayList < > ( Arrays . asList ( day ) ) ) ; } }
Creates a mapping between an {@code Activity} and the {@code Day} containing it.
Creates a mapping between an { @code Activity } and the { @code Day } containing it .