致命傷を避けるための例外実例集

Slide 1

Slide 1 text

க໋ইΛආ͚ΔͨΊͷ ྫ֎࣮ྫू Keishin Yokomaku / Startup Android #1

Slide 2

Slide 2 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू About Me ▸ Keishin Yokomaku ▸ Drivemode, Inc. / Principal Engineer ▸ KeithYokoma: GitHub / Twitter / Qiita / Tumblr / Stack Overﬂow ▸ Books: Mobile App Dev Guide / Android Academia / Grimoire of Android ▸ Fun: Gymnastics / Cycling / Photography / Motorsport ▸ Today’s Quote: “࣌୅͸ے೑” 2

Slide 3

Slide 3 text

ྫ֎ 3

Slide 4

Slide 4 text

Slide 5

Slide 5 text

5 ˒ˑˑˑˑ This app keeps crashing. Uninstalled.

Slide 6

Slide 6 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू ই͸ઙ͍͏ͪʹ࠹͙ ▸ ϦϦʔεઓུͱΫϥογϡݕ஌ͷ࢓૊Έ͸ඞਢςΫχοΫ ▸ Fabric(Crashlytics) ͰΫϥογϡϩάͷऩू ▸ Google Play Developer Console Ͱஈ֊తϦϦʔε ▸ ϢʔβϑΟʔυόοΫͷมԽʹؾ෇͘ ▸ ʮ࠷ۙ͜ΜͳϑΟʔυόοΫ͕Α͘དྷͯΔʯ ▸ ʮ͋ͷϑΟʔυόοΫݮͬͨʯ 6

Slide 7

Slide 7 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू ෆ৚ཧͱઓ͏ ▸ ໌Β͔ʹΫϥογϡ͢Δͱ෼͔Δ΋ͷ͚͕ͩݪҼͰ͸ͳ͍ ▸ Ϣʔβͷ࢖༻ঢ়گʹΑͬͯΫϥογϡͨ͠Γ͠ͳ͔ͬͨΓ͢Δ΋ͷ΋͋Δ ▸ ୺຤ͷҧ͍ɺ࢖͍ํͷҧ͍ɺଞʹΠϯετʔϧ͍ͯ͠ΔΞϓϦͷҧ͍ ▸ ༷ʑͳཁҼ͕༧૝֎ͷΫϥογϡΛ༠ൃ͢Δ ▸ ͱ͖ʹ͸ݟ஌Β͵ྫ֎͕ݪҼͰ͋Δ͜ͱ΋͋Δ ▸ ྫ֎ͷ໊લ΍ϝοηʔδ͔Βঢ়گ΍ཧ༝ΛಡΈऔΔεΩϧΛ਎ʹண͚Α͏ 7

Slide 8

Slide 8 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू Let’s get started! ▸ ຊ೔ͷྫ֎Ϩγϐ ▸ ༗໊Ͳ͜Ζ͔ΒͲϚΠφʔͳ΋ͷ·ͰϞϦϞϦίʔε 8 NullPointerException OutOfMemoryError StackOverﬂowError Illegal**Exception CursorWindowAllocationException TransactionTooLargeException DeadObjectException

Slide 9

Slide 9 text

NullPointerException 9

Slide 10

Slide 10 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू NullPointerException ▸ Ұ൪Α͋͘ΔΫϥογϡͷݪҼ ▸ ى͖Δཧ༝͸༷ʑ ▸ ίʔυ্Ͱͷݕࠪ࿙Ε ▸ Nullable Ͱͳ͍৔ॴʹ null Λ୅ೖ ▸ ΦϒδΣΫτͷϥΠϑαΠΫϧʹର͢Δߟྀ࿙Ε 10

Slide 11

Slide 11 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू NullPointerException ▸ Ή΍ΈʹରࡦΛऔͬͯ͸͍͚ͳ͍ ▸ e.g. ͋ΒΏΔϝιουͰ null νΣοΫΛೖΕΔ ▸ ๷ޚతʹͳΓ͗͢ΔͱޙʑͷϝϯςφϯεͰ଍ΛҾͬுͬͯ͠·͏ 11

Slide 12

Slide 12 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू NullPointerException ▸ ରࡦͷํ๏ ▸ ઃܭʹΑΔରࡦ ▸ ϝιου͕ null Λڐ༰͢Δ͔Ͳ͏͔ද໌͢Δ͜ͱͰɺ  ୭͕null νΣοΫͷ੹຿Λෛ͏͔ܾΊΔ ▸ NullObject ύλʔϯΛ࢖ͬͯɺԿ΋ى͖ͳ͍Α͏ʹ޻෉͢Δ 12

Slide 13

Slide 13 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू NullPointerException ▸ ରࡦͷํ๏ ▸ ϑϨʔϜϫʔΫͷίʔυͷ೺Ѳ ▸ Ͳ͏͍͏ঢ়گͰϝιου͕ null Λฦ͔͢஌͓ͬͯ͘ ▸ Support Library ͷ࣮ଶΛ஌͓ͬͯ͘ ▸ ۭ࣮૷ͷ··ϦϦʔε͞Ε͍ͯΔ͕࣌͋Δ ▸ ϑϨʔϜϫʔΫͷ࡞๏ʹ४ͨ͡࡞ΓํΛ֮͑Δ 13

Slide 14

Slide 14 text

OutOfMemoryError 14

Slide 15

Slide 15 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू OutOfMemoryError ▸ ը૾΍ಈըͳͲେ͖ͳσʔλΛѻ͏ͱඞͣ໨ʹ͢Δྫ֎ ▸ จࣈ௨Γɺۭ͖ͷͳ͍ώʔϓʹΦϒδΣΫτΛ࡞Ζ͏ͱ͍ͯ͠Δͱ͖ʹى͖Δ ▸ ରࡦํ๏͸ΘΓͱ໌շ ▸ େ͖ͳΦϒδΣΫτΛখ͘͢͞Δ ▸ ಉ࣌ʹͨ͘͞ΜͷΦϒδΣΫτΛώʔϓʹೖΕͳ͍ ▸ ϝϞϦϦʔΫΛͳ͘͢ 15

Slide 16

Slide 16 text

StackOverﬂowError 16

Slide 17

Slide 17 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू StackOverﬂowError ▸ ελοΫΛ࢖͍௵ͨ͠ͱ͖ʹى͖Δྫ֎ ▸ e.g. ແݶ࠶ؼݺͼग़͠ ▸ ݟམͱ͕ͪ͠ͳՕॴ ▸ ਂ͗͢ΔϨΠΞ΢τͷωετ: ϨΠΞ΢τ΋݁ہ͸ Java ͷΦϒδΣΫτʹͳΔ ▸ ਂ͗͢Δґଘؔ܎: ա৒ͳϨΠϠԽͰϝιουͷίʔϧελοΫʹݶք͕͘Δ 17

Slide 18

Slide 18 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू StackOverﬂowError ▸ ରࡦํ๏ ▸ ϨΠΞ΢τͷ֊૚ߏ଄ΛݮΒ͢ ▸ RelativeLayout ΍ ConstraintLayout ͳͲͰϑϥοτͳߏ଄ʹ͢Δ ▸ ద੾ͳཻ౓ͰઃܭΛ͢Δ ▸ Clean Architecture ΍ DDD ͳͲΛࢀߟʹ 18

Slide 19

Slide 19 text

Illegal**Exception 19

Slide 20

Slide 20 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू Illegal**Exception ▸ छྨ͸৭ʑ ▸ IllegalStateException, IllegalArgumentException, etc… ▸ ݺͼग़͞ΕΔଆ͕૝ఆ͍ͯ͠ͳ͍ঢ়ଶɾҾ਺ʹ௚໘ͨ͠ͱ͖ʹى͖Δ ▸ ݺͼग़͢ଆ͕Ҿ਺νΣοΫ΍ঢ়ଶνΣοΫΛ͢Δ͜ͱΛཁٻ͍ͯ͠Δ ▸ ୺຤ґଘͰެࣜͷ Javadoc ʹॻ͍ͯͳ͍ͱ͖ʹඈΜͰ͘Δ͜ͱ͕͋Δ ▸ ո͍͠ͳʁͱࢥͬͨΒ͙͢ʹঢ়ଶ΍Ҿ਺ΛϩάʹͭΊͯूΊΒΕΔ࢓૊ΈΛ 20

Slide 21

Slide 21 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू Illegal**Exception ▸ ରࡦํ๏ ▸ ͙͢ʹ௚ͤΔ΋ͷ͹͔ΓͰ͸ͳ͍͜ͱʹཹҙ͢Δ ▸ ඞཁͳ৘ใΛूΊɺରࡦΛ࿅͔ͬͯΒ௚͢͜ͱ ▸ Crashlytics ͷϩάऩूػೳͰࣄલ৚݅ΛνΣοΫ͢ΔͱΑ͍ 21

Slide 22

Slide 22 text

CursorWindowAllocation Exception 22

Slide 23

Slide 23 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू CursorWindowAllocationException ▸ σʔλϕʔεΛѻ͏ͱ໨ʹ͢Δྫ֎ ▸ Cursor ͕΋ͭσʔλ͕ڐ༰ൣғΛ௒͑ͨͱ͖ʹى͖Δ ▸ ϦϑΝϨϯεʹ Javadoc ͕ແ͍ྫ֎͕ͩɺࡶʹ࡞Δͱ໨ܸ͢Δϋϝʹ ▸ CursorWindow ΫϥεͷதͰϋϯυϦϯά͍ͯ͠Δ ▸ CursorWindow.java: http://bit.ly/2eKlL5y 23

Slide 24

Slide 24 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू CursorWindowAllocationException ▸ ରࡦํ๏ ▸ ҰؾʹେྔͷσʔλΛऔಘ͍ͯ͠Δ෦෼Λࡉ੾Εʹ͢Δ ▸ σʔλϕʔεʹڊେͳσʔλΛอ؅͠ͳ͍ ▸ ࢖͍ऴΘͬͨ Cursor ͸ close ͢Δ 24

Slide 25

Slide 25 text

TransactionTooLarge  Exception 25

Slide 26

Slide 26 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू TransactionTooLargeException ▸ ϓϩηεؒ௨৴ͰϝϞϦΛ࢖͍͗ͨ͢ͱ͖ʹى͖Δྫ֎ ▸ 1ͭͷϓϩηεʹରׂͯ͠Γ౰ͯΒΕΔϓϩηεؒ௨৴༻ͷྖҬ͸1mB ▸ ҙ֎ͳͱ͜ΖͰϓϩηεؒ௨৴͸࢖ΘΕ͍ͯΔ ▸ Context#startActivity ▸ PackageManager#queryIntentActivities ▸ ଞଟ਺ 26

Slide 27

Slide 27 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू TransactionTooLargeException ▸ Intent ͷ extra ʹ 1mB Λ௒͑Δ String Λ౉͢͜ͱͰ΋ى͖Δఔ౓ʹ͸਎ۙͳͱ ͜ΖʹՄೳੑ͕͋Δ ▸ ରࡦํ๏ ▸ ڊେͳσʔλΛ௚઀ѻΘͳ͍ ▸ ϓϩηεؒ௨৴ͷ࣌ؒΛ୹͘͢Δ ▸ ϓϩηεؒ௨৴ͷճ਺ͦͷ΋ͷΛݮΒ͢ 27

Slide 28

Slide 28 text

DeadObjectException 28

Slide 29

Slide 29 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू DeadObjectException ▸ ࢮΜͩϓϩηεʹ࿩͔͚ͨ͠ͱ͖ʹى͖Δྫ֎ ▸ ௨৴૬खͷϓϩηε͕͍ͭ΋ੜ͖͍ͯΔͱ͸ݶΒͳ͍ ▸ ରࡦํ๏ ▸ ServiceConnection ΍ IBinder.DeathRecipient Ͱࢮ׆؂ࢹ ▸ ڊେͳσʔλΛ௨৴ʹͷͤͳ͍ ▸ System Service ͸ࢮ׆؂ࢹͰ͖ͳͦ͞͏…… 29

Slide 30

Slide 30 text

·ͱΊ 30

Slide 31

Slide 31 text

Slide 32

Slide 32 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू ·ͱΊ ▸ ରࡦํ๏ͦͷ΋ͷʹֵ৽తͳ͜ͱ͸΄ͱΜͲແ͍ ▸ Α͋͘Δ࣮ྫΛͦͷ··ద༻Ͱ͖Δ͜ͱ΋ଟ͍ ▸ ߟ͑ํͷجຊ ▸ ॲཧͷ୯Ґ΍σʔλΛখ͘͞ࡉ͔͘͢Δ ▸ ઃܭͱද໌Ͱ੹຿Λ໌Β͔ʹ͢Δ 32

Slide 33

Slide 33 text

க໋ইΛආ͚ΔͨΊͷྫ֎࣮ྫू ·ͱΊ ▸ ͍͔ʹૣ͘৘ใΛूΊͯରࡦ͕औΕΔ͔͕ॏཁ ▸ ஈ֊తϦϦʔε ▸ Ϋϥογϡϩάͷऩू ▸ ϢʔβϑΟʔυόοΫͷղੳ 33