Peb npaj koj qhov kev pom! Kev ua tau zoo nrog ONMA scout android app kev txhim kho yog lav.
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Tej zaum koj yuav tau hnov txog Android programmierung tsis ntev los no thiab xav paub tias koj tuaj yeem pib li cas. Muaj ntau yam zoo rau qhov tshiab mobile operating system. Rau cov pib, nws muab koj nkag mus rau lub khw loj loj app nrog dhau 3 lab apps. Koj tuaj yeem yooj yim siv cov apps no yog tias koj paub yuav ua li cas rau lawv kom raug. Hauv qab no yog qee qhov tseem ceeb tshaj plaws ntawm Android:
Txawm hais tias koj nyuam qhuav pib lossis tab tom nrhiav txhim kho koj cov kev txawj programming, tso saib cov nkauj lyric nrov ntawm koj lub vev xaib lossis app yog txoj hauv kev lom zem rau kev kawm. Nws kuj tseem qhia txog cov kev coj ua zoo tshaj plaws rau kev txhim kho Android thiab yog ib txoj hauv kev zoo los ua kom koj lub app txaus nyiam rau cov neeg siv khoom. Nws kuj tseem muab sijhawm rau koj los qhia koj cov kev txawj programming rau cov phooj ywg thiab tsev neeg.
Tag nrho Android Online-Kurs muaj 43 zaj lus qhia thiab suav nrog ob lub luag haujlwm ua haujlwm hauv Android apps. Cov lus qhia npog cov ntsiab lus tseem ceeb ntawm Android app kev txhim kho thiab yuav coj koj mus rau tag nrho cov txheej txheem txij thaum pib mus txog thaum kawg. Ib qho downloadable PDF version ntawm cov lus qhia kuj suav nrog. Rau cov ncauj lus siab dua, Koj tuaj yeem xaiv rau eBooks ntxiv. Android Online-Kurs muaj 43 zaj lus qhia uas qhia koj yuav ua li cas los tsim ib lub app.
AsyncTask yog chav kawm paub daws teeb meem hauv Android programming lus uas ua rau koj lub app ua haujlwm hauv keeb kwm yav dhau. Nws tsis yog threading moj khaum, tab sis nws tuaj yeem siv los ua cov haujlwm tom qab, zoo li nyeem cov ntaub ntawv thiab ua cov ntaub ntawv. Raws li lub npe qhia, nws yog siv rau kev ua haujlwm tom qab thiab hloov kho cov xwm txheej ntawm tus neeg siv interface thaum lub sijhawm ua haujlwm. Lub ntsiab drawbacks ntawm AsyncTask yog lub sij hawm lub ntsiab lus xau, nco callbacks, thiab kev coj cwj pwm tsis sib haum thoob plaws hauv lub platform. Nws tseem nqos cov kev zam los ntawm doInBackground thiab muaj kev siv me me dua Executor.
Koj tuaj yeem siv AsyncTask-framework los ntawm kev siv AsyncTask API. Nws yog ib qho yooj yim los pib tsim Android apps nrog lub moj khaum no. Ua ntej, koj tuaj yeem tshawb txog ntau yam nta ntawm lub moj khaum no. Piv txwv li, asyncTask cia koj upload keeb kwm nkag los ntawm huab, koj tsis tas yuav siv lub ntsiab UI xov kom ua tiav qhov haujlwm no. Dhau li, Koj tuaj yeem siv nws los siv ntau lwm yam dej num hauv Android programing ib puag ncig.
AsyncTask-framework rau Android muab cov chav kawm rau kev txhais thiab tswj xyuas lub xeev ntawm daim ntawv thov. Raws li lub npe implies, AsyncTask-Framework yog lub tsev qiv ntawv qib siab uas tso cai rau koj los tsim cov apps rau Android. Thiab txawm nws complexity, AsyncTask-Framework tso cai rau koj los sau cov ntawv thov sib tham hauv Android.
ListView-Element yog lub thawv rau saib cov ntsiab lus thiab yuav tsum tau txhais hauv cov ntaub ntawv XML-Layout. Nws qhov dav, qhov siab, ob sab, thiab Divider tuaj yeem txhais tau hauv Android code. Koj yuav siv ArrayAdapter los txuas cov ntaub ntawv rau cov npe saib. Hauv Android programming tutorial, peb yuav hais txog cov hauv paus ntawm ListView thiab yuav siv nws li cas hauv Android app.
Daim ntawv pom yog daim ntawv thov tus neeg siv interface, uas qhia cov npe ntawm cov khoom. Cov npe tuaj yeem kho tau los ntawm tus neeg siv, los yog nws tuaj yeem tso tawm kom pom. ListViews tau txais cov ntaub ntawv los ntawm adapters uas nyem cov ntaub ntawv los ntawm lwm qhov chaw. Lawv kuj siv loaders los populate lub Adapter. Thaum tus neeg siv cuam tshuam nrog cov npe saib, txoj kev toString rov qab ib txoj hlua sawv cev ntawm cov khoom uas tau dhau mus rau nws. Qhov no yog cov ntaub ntawv tso tawm hauv ListView. Nws txhawb ntau qhov kev kuaj xyuas, thiab koj tuaj yeem tshawb nrhiav cov khoom los ntawm kev ntaus hauv lawv lub npe.
Lub Android ListView yog ViewGroup uas qhia cov npe ntawm cov khoom scrollable. Daim ntawv no cia li ntxig cov khoom siv lub adapter, which pulls data from an array or database. Lub adapter ces hloov cov ntaub ntawv mus rau hauv qhov tshwm sim views, uas ces muab tso rau hauv daim ntawv. ListView adapter yog qhov nruab nrab ntawm cov ntaub ntawv qhov chaw thiab Saib. Nws tuav cov ntaub ntawv, sau rau hauv cov kev xav thiab tom qab ntawd ntxig rau hauv ListView.
Yog hais tias koj xav mus debug koj app tsis debugging lub Android runtime, Koj tuaj yeem siv lub cuab yeej Android Studio. Siv cov cuab yeej no, Nco ntsoov tias koj ua raws README ntawm Android-runtime repository. Koj tuaj yeem siv cov cuab yeej adb los qhib lub plhaub ntawm koj lub cuab yeej thiab txheeb xyuas tus txheej txheem ID. Thaum koj pom tus txheej txheem ID, koj tuaj yeem siv DS-5 debug kev sib txuas los thauj cov cim rau koj cov txheej txheem app thiab teeb tsa txoj hauv kev tshawb nrhiav hauv tsev qiv ntawv sib koom.
Thaum koj tau mus txog koj qhov breakpoint, lub app yuav ncua kev ua haujlwm thiab qhia lub qhov rais kho qhov teeb meem. Tom qab ntawd koj tuaj yeem tshawb xyuas qhov sib txawv thiab cov kab lus hauv cov cai. Qhov no yuav tso cai rau koj cais tawm thiab txheeb xyuas qhov ua rau muaj kev ua yuam kev lossis kev ua haujlwm tsis ua haujlwm. Koj tuaj yeem yooj yim ntxiv qhov tawg los ntawm nias lub gutter raws kab ntawm txoj cai lossis los ntawm nias Control + F8. Txhawm rau ntxiv qhov tawg, koj yuav tsum xaiv Debug thiab nyem lub xub nyob ib sab ntawm cov kab uas xav tau.
Thaum siv SDK, Tej zaum koj yuav xav pab kom USB debugging ua tus tsim tawm. Txawm li cas los, koj yuav tsum tsis txhob tso USB debugging rau mus tas li. Tej zaum koj yuav xav ua kom nws ib zaug tab sis qhov txaus ntshai ntawm kev ua kom nws mus tas li yog ntau dua li cov txiaj ntsig. Txhawm rau zam cov kev pheej hmoo no, koj yuav tsum nco ntsoov tias koj muaj Android SDK ntsia ua ntej koj pib debugging. SDK yog qhov tseem ceeb rau cov neeg tsim tawm hauv Android vim tias nws ua kom yooj yim rau ntau txoj haujlwm thiab ua rau lawv ua tau sai thiab yooj yim..
Open-Source xwm ntawm Android muaj ntau yam txiaj ntsig. Lub software muaj nyob rau ntawm ntau yam khoom siv, suav nrog smart TVs, tub yees, thiab point-and-shoot koob yees duab. Koj tuaj yeem rub tawm nws dawb thiab sim nrog nws. Yog tias koj xav tsim lub smartphone lossis lwm yam khoom siv, Android yog lub platform siv. Tab sis nws tseem ceeb kom nkag siab tias muaj qhov tsis zoo rau Open-Source, ib yam nkaus. Hauv tsab xov xwm no, peb yuav ua tib zoo saib xyuas cov teeb meem no thiab muab cov ntsiab lus luv luv rau koj ntawm qee qhov zoo thiab qhov tsis zoo ntawm qhov qhib qhov chaw ua haujlwm no.
Android yog qhib qhov chaw, uas txhais tau hais tias Google-tsim software yog pub dawb rau siv. Google tseem tab tom nqis peev hauv Android thiab tau txais txiaj ntsig los ntawm nws. Qhov Open-Source xwm ntawm Android programming tso cai rau lwm lub tuam txhab tswj hwm thiab txhim kho nws. Nws cov koob meej yog loj hlob, thiab nws yuav txuas ntxiv mus ntxiv rau yav tom ntej. Muaj ntau lub peev xwm rau Android, yog li siv sijhawm los kawm cov hauv paus. Koj yuav zoo siab koj tau ua.
Android tso cai rau koj sau cov ntawv thov rau txhua hom khoom siv thiab sib xws nrog txhua qhov kev ua haujlwm loj. Nws qhib qhov xwm txheej tso cai rau cov neeg tsim khoom siv ntau qhov chaw los kawm cov hauv paus ntawm Android programming. Vim tias Android yog qhov chaw qhib, cov neeg tsim khoom tuaj yeem kawm paub tsim lawv cov ntawv thov rau txhua lub computer. Android SDK tso cai rau koj los tsim thiab sim koj cov apps ntawm txhua lub computer, tsis muaj teeb meem dab tsi OS nws tab tom khiav. Qhov no ua kom cov neeg tuaj saib dav dua rau koj daim ntawv thov.