Peb npaj koj qhov kev pom! Kev ua tau zoo nrog ONMA scout android app kev txhim kho yog lav.
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Android app programming yog qhov nyuaj tab sis muaj txiaj ntsig zoo uas yuav ua rau koj muaj kev sib tw dhau ntawm koj cov neeg sib tw. Cov txheej txheem yog nyob ntawm ntau xyoo ntawm kev paub hauv kev txhim kho software thiab tshwj xeeb rau koj cov khoom xav tau. Hauv tsab xov xwm no, peb yuav piav qhia yuav ua li cas los tsim ib qho Android Activity Lifecycle Callback thiab SettingsFragment. Peb tseem yuav hais txog yuav ua li cas siv Java ua hom lus programming rau Android. Thaum kawg, cov txheej txheem yuav coj koj los ntawm kos mus rau ib qho khoom tiav.
Java yog ib qho ntawm cov lus programming nrov tshaj plaws siv rau Android app kev txhim kho. Muaj ntau pua lub apps ntawm Play Store uas tau sau hauv Java. Cov lus yooj yim kawm thiab muaj qhov loj, txhawb zej zog. Qhov no ua rau nws yog qhov kev xaiv zoo rau cov neeg tsim khoom uas tab tom nrhiav cov lus nrawm thiab txhim khu kev qha rau kev tsim cov ntawv thov mobile. Qee cov apps nrov tshaj plaws tsim hauv Java suav nrog Twitter thiab Spotify.
Java muaj ntau txheej APIs, xws li XML parsing thiab database txuas. Nws tseem yog lub platform-kev ywj pheej programming lus, txhais tau hais tias cov neeg tsim khoom uas sau Java code tuaj yeem khiav ntawm Windows, Linux, o Mac OS. Cov txiaj ntsig ntawm kev siv Java rau kev txhim kho mobile app ua rau nws yog qhov kev xaiv zoo tshaj plaws rau cov neeg tsim khoom txawb.
Java yog ib hom lus nrov tshaj plaws rau kev tsim cov apps, tshwj xeeb tshaj yog rau beginners. Cov lus kuj tseem txhawb nqa los ntawm Android Studio. Vim nws muaj koob meej thiab siv dav, Java yog lub programming lus xaiv los tsim cov apps rau Android. Txawm li cas los, muaj qhov zoo rau kev siv lwm yam lus, zoo li Kotlin, rau Android app txhim kho.
Java yog hom lus hais txog khoom tsim los ntawm Sun Microsystems hauv 1995. Nws muaj zog tswj kev nco nta thiab yog concurrent. Nws kuj tseem txhawb nqa cov khoom khib nyiab los tswj lub cim xeeb hauv cov lej, uas zoo heev simplifies kev tswj nco. Qhov no txhais tau hais tias Java code tuaj yeem ntev dua thiab nyuaj dua li Kotlin code.
Vim nws versatility thiab robustness, Java yog qhov kev xaiv zoo tshaj plaws rau Android app kev txhim kho. Cov lus yooj yim kawm thiab siv cov tsev qiv ntawv qhib uas ua rau cov txheej txheem yooj yim dua. Cov ntawv thov Java muaj peev xwm txhawb nqa ntau yam txheej txheem, uas yog qhov tseem ceeb rau cov tuam txhab uas xav tau hnyav. Lawv kuj tuaj yeem tswj tau ntau tus neeg siv.
Lwm txoj hauv kev los tsim Android apps yog Corona. Corona kawm tau yooj yim dua li Java thiab siv cov lus LUA. Nws kuj muab SDK uas ua rau coding yooj yim dua. Nws muaj ntau yam txiaj ntsig, xws li kev sib raug zoo nrog txhua lub tsev qiv ntawv ib txwm muaj. Nws kuj tseem siv tau los tshaj tawm cov apps rau lwm lub platform. Corona feem ntau yog siv los ua kev ua si. Code yog nkag mus rau hauv cov ntawv nyeem thiab tuaj yeem khiav ntawm emulators yam tsis tau sau.
A developmentsumgebung yog ib puag ncig uas tso cai rau koj los tsim cov ntawv thov rau Android. Nws pab koj teeb tsa koj lub app kom ua haujlwm tau zoo ntawm txhua yam khoom siv hauv Android. Piv txwv li, koj yuav xav tsim ib qhov project uas cia koj ua haujlwm nrog cov peev txheej sib txawv ntawm cov khoom siv sib txawv. Qhov project kuj yuav tsum yooj yim rau kev taug kev thiab yuav tsum muaj qhov chaw huv thiab muaj kev sib koom ua ke. Nws kuj tseem yuav tso cai rau koj los tsim koj daim ntawv thov yam tsis muaj teeb meem.
Android ib puag ncig xav kom cov neeg tsim khoom siv cov ntaub ntawv XML los txhais cov hlua UI. Cov ntaub ntawv XML tuaj yeem txhais cov ntawv qhia zaub mov, hom, xim, thiab animations. Cov ntaub ntawv no kuj txhais cov txheej txheem ntawm kev ua haujlwm ntawm cov neeg siv interfaces. Los ntawm kev siv cov ntaub ntawv XML, koj tuaj yeem txhim kho koj lub app kom khiav ntawm cov khoom siv sib txawv thiab tso saib cov kev daws teeb meem. Koj tseem tuaj yeem txhais cov ntaub ntawv sib txawv hauv koj qhov project. Txoj kev no, koj yuav muaj kev hloov pauv ntau dua yav tom ntej.
Txoj kev ua neej nyob ntawm Android kev ua si yog siv kom tau txais cov ntaub ntawv hais txog lub xeev ntawm kev ua ub no, xws li nws lub xeev tam sim no. Hauv qee kis, txoj kev lifecycle yog invoked ua ntej ib qho kev ua ub ua no puas. Saib cov zis ntawm txoj kev no, koj tuaj yeem siv logcat. Nws qhia koj cov zis ntawm lub emulator, ntaus ntawv, los yog ob leeg. Koj tuaj yeem pom cov ntsiab lus hauv logcat rau onCresume, ntawm Pause, thiab onStop txoj kev.
Thaum ib qho kev ua si rov pib dua, lub system yuav hu rau onResume() hu rov qab. Koj yuav tsum coj kom zoo dua ntawm qhov xwm txheej no los khaws lub xeev hauv kev nco, txawm tias koj qhov haujlwm raug ncua. Txoj kev no, koj cov neeg siv yuav muaj kev nkag mus rau koj lub app ua haujlwm thaum lub sijhawm ua haujlwm raug ncua.
Txoj kev hu xov tooj rau lub neej kuj tseem siv tau los tswj kev hloov pauv ntawm ntau lub xeev ntawm ib qho kev ua ub no. Piv txwv li, streaming video player tuaj yeem nres thiab rov pib dua cov yees duab thaum tus neeg siv hloov cov apps. Nws tseem tuaj yeem txiav nws txoj kev sib txuas hauv network thaum tus neeg siv hloov cov apps. Thiab, thaum tus neeg siv rov qab los, nws tuaj yeem rov pib ua yeeb yaj kiab los ntawm tib txoj haujlwm uas nws tau tso tseg.
Thaum tsim ib qho kev ua si, nws yuav mus dhau ntawm onCreate() thiab ntawm Destroy() txoj kev. Cov txheej txheem no tsuas yog hu ua ib zaug thaum lub sijhawm ua haujlwm ntawm lub neej. Txawm li cas los, yog tias tus neeg siv kaw daim ntawv thov ua ntej qhov kev ua tiav, lub onSaveInstanceState() hu rov qab yuav hu.
Tsuas yog tsim ib qho kev ua si, Koj tuaj yeem siv lub onStart() txoj kev rov pib ua haujlwm. Txoj kev no yog hu los ntawm Android system tom qab nws tsim ib qho haujlwm. Thiab, tom qab ib qho haujlwm tau raug tso tseg, nws tuaj yeem rov pib dua los ntawm kev hu rov pib dua. Qhov no tuaj yeem pab lub kaw lus tswj hwm lwm cov txheej txheem uas yuav ua haujlwm tom qab, yog li txhim kho kev ua tau zoo tag nrho ntawm ib daim ntawv thov. Txawm li cas los, koj yuav xav xav txog ob peb cov ntsiab lus ua ntej siv cov txheej txheem no.
Thawj kauj ruam hauv kev tsim Android Activity Lifecycle Callback yog kom nkag siab tias kev hu rov qab ua haujlwm li cas thiab thaum lawv raug hu. Thawj qhov hu ua onCreate(). Thaum txoj kev no yog invoked, qhov kev ua si yog tsim thiab tsim txhua yam tsim nyog views, kev khi, thiab cov npe. Tom qab lub onCreate() hu rov qab, OS yuav hloov kev tswj rau onResume() los yog onDestroy().
Thaum tsim ib daim ntawv thov Android, koj tuaj yeem siv PreferenceFragment los ua kom cov nplooj ntawv teeb tsa zoo nkauj thiab zoo ib yam. Qhov no yuav ua kom koj cov neeg siv khoom muaj kev paub zoo ib yam txawm tias lawv tab tom saib qhov twg. Yuav siv hom kev tivthaiv no, koj yuav tsum ncua chav PreferenceActivity. Ces, koj yuav tsum siv cov onBuildHeaders() hu rov qab.
Koj tseem tuaj yeem tsim cov Fragments tshwj xeeb. Cov fragments no yog ib qho kev hloov pauv ntau dua li koj cov haujlwm. Cov fragments yog qhov pib modular seem ntawm koj cov haujlwm, thiab muaj lawv tus kheej lifecycle. Lawv kuj tau txais lawv tus kheej cov txheej xwm tawm tswv yim. Tsis tas li ntawd, koj tuaj yeem ntxiv cov seem rau koj lub app thaum nws tab tom khiav.
Qhov PreferenceFragment yog ib qho khoom siv uas muaj cov hierarchy ntawm cov khoom nyiam. Nws yog siv hauv Android apps thiab txuag qhov kev nyiam rau SharedPreferences. Nws tsis txhawb cov khoom tsim cov ntsiab lus, txawm li cas los xij. Nws tuaj yeem txuas ntxiv DialogPreference thiab TwoStatePreference los ntawm kev siv qhov chaw API.
Yog tias koj lub app txhais tau tias yog tus kheej ntau dua, Koj tuaj yeem siv PreferenceFragment. Cov chav kawm no raug pom zoo rau Android 3.0 thiab siab dua. Nws tso cai rau koj los kho qhov zoo thiab zoo ntawm koj lub app. Koj tuaj yeem tsim graphical user interface rau koj daim ntawv thov. Lub layout kuj yog customizable heev.
A PreferenceFragment yog ib txoj hauv kev yooj yim los cawm cov neeg siv khoom nyiam. Thaum koj hloov cov kev nyiam hauv koj lub app, Android yuav cia li khaws cov kev hloov pauv hauv cov ntaub ntawv SharedPreferences. Tab sis qhov no txhais tau tias ntau txoj cai los daws cov kev hloov pauv. Ntau lub apps yuav tsum mloog cov kev hloov pauv hauv cov ntaub ntawv SharedPreferences.