Yadda ake Koyan Shirye-shiryen App na Android

Idan kuna son koyon shirye-shiryen aikace-aikacen Android, Ba ku kadai bane. A gaskiya, yana da sauƙin farawa! Fara da Android Studio, Yanayin ci gaban kyauta na Google. Hakanan kuna buƙatar Kit ɗin Ci gaban Java. Sannan, za ka iya fara rubuta apps na farko. A ƙarshe, za ku ci gaba zuwa Intents, Java, Aiki Lifecycle Callbacks, da sauransu!

Ja-da-sauke

Jawo-da-saukar da shirye-shiryen aikace-aikacen Android hanya ce mai sauƙi kuma mai ƙarfi wacce za ta iya taimaka muku ƙirƙirar aikace-aikacen mu'amala sosai. Tsarin ja da sauke yana ba ku damar motsa abubuwa a cikin app ba tare da shafar sauran aikace-aikacen ba. Ana aika abubuwan ja ga masu sauraro ta hanyar taron Android. Lamarin ja yana ƙunshe da bayanai game da yanayin abun kuma yana iya haɗawa da bayanai kamar haɗin gwiwar X-y. Mai sauraron taron yana karɓar bayanai kuma ya kira hanyar getX() ko samu() don samun matsayi na yanzu na wurin ja. Idan an gama aikin ja, mai sauraro ya mayar da boolean gaskiya ko karya.

Jawo da sauke shirye-shiryen aikace-aikacen Android yana yiwuwa tare da Eclipse 4.4 (Luna) da Java 1.7. Don aiwatar da ja-da-saukarwa, kuna buƙatar ƙara OnTouchListener zuwa Ayyukanku. Sannan, ƙirƙirar DragShadowBuilder wanda ke ƙayyade hoton da za a nuna yayin aikin ja.

Jawo da sauke shirye-shiryen aikace-aikacen Android ya ƙunshi yin amfani da azuzuwan abubuwan ja da ja da masu sauraro. Abubuwan ja da baya suna farawa da fararwa mai amfani. Sannan, app ɗin yana ba da startDragAndDrop() kira baya. Idan mai sauraron taron ya dawo karya, tsarin ba zai kira hanyar dawo da kira ba. Ajin DragEvent yayi kama da onTouchEvent.

Kuna iya canza halayen taron ja-da-jida ta hanyar tsallake hanyar onProvideShadowMetrics. This method returns information regarding the size and touch point of the drag event. You can also modify the drag-and-drop gesture by overriding the onDrawShadow method.

Drag-and-drop Android app programming is a simple and flexible technique that lets you build high-quality mobile applications. With drag-and-drop, you can also trigger system events when users perform drag and drop actions.

Abubuwan da ake nufi

Intents are used to communicate between different components in an Android app. An Android application can support both explicit and implicit intents, which are used to control the flow of data from one application to another. An example of this would be a browser window that redirects a user to another application when they open it.

Intents can be a single number or a string, kuma ana amfani da su don jawo wasu ayyuka a cikin app. Baya ga jawo wasu abubuwan da ke cikin app, Hakanan za'a iya amfani da niyya don motsa ayyuka a cikin ƙa'idar. Makullin shine a yi amfani da su cikin hikima. Ya kamata ku nisanci serializable ko bayanan da za a iya tattarawa yayin aiki tare da niyya.

Misali, zaka iya amfani da kirtani ɗaya don nuna bayanan haja ga mai amfani. Sannan, za su iya danna maɓallin sauraron don ganin cikakkun bayanai na kuɗin hannun jari. Sa'an nan app ɗin zai nuna waɗannan cikakkun bayanai a cikin duban jeri. Ana iya keɓance ƙa'idar ta hanyar kyale masu amfani su zaɓi haja da ake so. Sannan za ta nuna jerin hannayen jari bisa ga ka'idojin da aka zaɓa, gami da duk wani sayayya mai jiran aiki da oda na siyarwa.

Aikace-aikacen Android sau da yawa sun ƙunshi allon fuska da yawa. Wani lokaci, masu amfani suna buƙatar canzawa tsakanin apps don dalilai daban-daban. Don cimma wannan, suna amfani da tsarin Intent. Ana amfani da intents don haɗa ayyuka a cikin ƙa'idar guda ɗaya, haka kuma tsakanin apps. Don canzawa tsakanin apps, ya kamata ka ƙirƙiri sabon abin niyya kuma amfani da hanyar Android mai dacewa.

Intents suna ba da damar ƙa'idodin Android don samar da ayyuka kama da gidan yanar gizo. Don yin wannan, Aikace-aikacen Android na iya aiwatar da tace niyya don hanyoyin yanar gizo. Wannan yana nufin cewa hanyoyin haɗin yanar gizon da ke nuna shafukan yanar gizo za su buɗe manhajar Android maimakon shafin yanar gizon. Bugu da kari, Android 12 gabatar da maƙasudin yanar gizo gabaɗaya, waɗanda ake amfani da su don buɗe tsohuwar ƙa'idar burauzar mai amfani.

Aiki Lifecycle Callbacks

Lokacin da ka rubuta code a cikin Android apps, Sau da yawa za ku iya ci karo da Kiran Taimako Lifecycle. Waɗannan sake kiran waya suna sanar da ku lokacin da ya kamata a rufe app ɗin ku, sake farawa, ko kuma ya koma jihar da ta gabata. An yi sa'a, Ana iya amfani da waɗannan sake kiran waya a cikin mahallin Ayyuka da rarrabuwa.

Akwai nau'i uku na Aiki Lifecycle Callbacks. Na farko, m(), ana kiran duk lokacin da wani aiki ya fara bayyana akan allon. Na biyu, kan Ci gaba(), ana kiranta lokacin da wani aiki ya dawo daga dakatarwa. Wannan babban kira ne mai mahimmanci ga kowane app na Android saboda yana iya hana app ɗinku yin dogon aiki.

Ya kamata ku fahimci Android API don yin waɗannan kiran baya. Hanyoyin onStart da onStop ana kiran su sau da yawa ta tsarin. Wannan yana nufin cewa app ɗin ku na iya kiran hanyar onStart sau da yawa. Wannan zai sa ayyukanku su zama bayyane da ɓoye. Hakanan yakamata ku iya faɗi lokacin da aikin ya lalace ta hanyar duba saƙonnin logcat.

The onCreate da onDestroy callbacks suna haifar da OS ne sakamakon mu'amalar mai amfani. Masu haɓakawa kuma za su iya soke kiran da aka yi. Duk da haka, lokacin ƙetare kiran da aka yi, developers ya kamata ko da yaushe kira super class hanya. Rashin yin haka na iya haifar da app ɗin yana gudana cikin wani yanayi mai ban mamaki ko ma da hadari.

Kiran sake zagayowar rayuwa yana taimaka muku fahimtar lokacin da aikace-aikacenku yakamata ya shigar da yanayin da aka dakatar ko tsayawa. Kada ku aiwatar da ƙididdiga masu ƙarfi a wannan lokacin, kamar yadda zai iya jinkirta sauyawa zuwa yanayi na gaba kuma ya ƙare ƙwarewar mai amfani.

Shiga

Shiga aikace-aikacen Android na iya zama kayan aiki mai amfani ga masu haɓakawa. Android tana amfani da tsarin tsakiya don adana saƙonnin log, wanda za'a iya tace ta kashi ko fifiko. Kuna iya keɓance saƙon ta hanyar rubuta bayanan log na al'ada waɗanda suka dace da ayyukan app ɗin ku. Akwai hanyoyi da yawa don shiga da tantance bayanan log.

Hanya mafi sauƙi don shiga ita ce ta amfani da ginanniyar ajin Log. Hanyoyin shiga suna karɓar gardama biyu ko uku. Yawancin saƙonnin log ɗin suna ɗauke da gardama biyu. Dole ne hujjojin su kasance na nau'in String. Irin wannan nau'in katako yana iyakancewa, amma kayan aiki ne masu amfani don dalilai da yawa.

Shiga aikace-aikacen Android ya zama sanannen tsarin shirye-shirye ga masu haɓakawa. Gabaɗaya, aikace-aikacen Android yakamata ya shiga cikin abubuwan da suka faru a duk lokacin da suka faru. Idan aikace-aikacen yana buƙatar gyara matsala, ya kamata ya shigar da bayanan da ke taimakawa masu haɓakawa su gyara aikace-aikacen. Hakanan zaka iya shigar da bayanan kuskure ta amfani da Log.d() hanya. Hanya ta ƙarshe kuma za ta iya shigar da ƙima masu canzawa da buga saƙonni.

Yayin da ake gyara kuskure yana taimakawa idan akwai kurakurai, wuce gona da iri na iya rage aiki. Mafi kyawun aiki shine a yi amfani da rajistar kuskure kawai don haɓakawa, kuma cire shigar da kalmar verbose kafin buga aikace-aikacen ku. A matsayin mai haɓakawa, ya kamata a ko da yaushe ku sake duba abubuwan da aka fitar kafin buga shi. Android SDK ya zo tare da hadedde aji aji. Yana rubuta bayanan aikace-aikacen zuwa wani log da ake kira LogCat. Duk da haka, wannan hanyar tana da wasu matsalolin aiki, don haka ya kamata a yi amfani da shi kawai idan ya cancanta.

Hakanan zaka iya duba tsarin rajistan ayyukan a cikin Android. Waɗannan rajistan ayyukan sun ƙunshi bayanai akan komai daga abubuwan da suka faru na nazari zuwa wuri da rajistan ayyukan. Kuna iya tace kayan aikin log ɗin ta kunshin aikace-aikacen tare da taimakon kayan aiki kamar Android Studio.