Update Directory method to not use type cast

[lyeyixian]

TravelPlanObject method still haven't figure out yet

[codecov-io]

Codecov Report

Merging #159 into master will decrease coverage by 0.25%.
The diff coverage is 21.73%.

@@             Coverage Diff              @@
##             master     #159      +/-   ##
============================================
- Coverage     66.17%   65.92%   -0.26%     
- Complexity      766      768       +2     
============================================
  Files           116      116              
  Lines          2510     2512       +2     
  Branches        309      307       -2     
============================================
- Hits           1661     1656       -5     
- Misses          724      733       +9     
+ Partials        125      123       -2     

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/seedu/address/model/Directory.java	100.00% <ø> (ø)	1.00 <0.00> (ø)
...u/address/model/util/SampleWanderlustDataUtil.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...in/java/seedu/address/model/wishlist/Wishlist.java	30.95% <7.14%> (-13.50%)	9.00 <1.00> (+2.00)	⬇️
...rc/main/java/seedu/address/model/ModelManager.java	76.36% <60.00%> (+2.97%)	34.00 <1.00> (-1.00)	⬆️
...ava/seedu/address/model/travelplan/TravelPlan.java	81.31% <100.00%> (+0.20%)	34.00 <1.00> (+1.00)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7e3b308...abb82fc. Read the comment docs.

[underthehai]

LGTM

[jiaweiteo]

LGTM