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Up to now, using Compose, you built up the interface for the chat app using mock data. It’s like you made the yummy-looking but completely fake cake some stores display. But you want to have your cake and eat it too! In this lesson, you’ll learn how to make your app more functional by adding interactivity.
You need to do two main things to make the chat interface interactive. First, when you tap the text box, the keyboard comes up, but typing doesn’t display in the text box. So, you’ll need to make the text that’s typed appear in the text box. Secondly, when you hit the send button, the text that’s in the text box should be added to the list of chat messages and simultaneously cleared from the text box.
But before you start writing code, you need an understanding of how interactivity works in Compose.
State
To make any app functional, you must know how to manage state. At its core, every app works with specific values that can change. For example, in Kodeco chat, a user can:
Unh e qiq qsoj liflitu.
Porezo o vdon zetfabu.
Ihtioc iw exowe igqixvnefb ka e vvov voksuwo.
Vlave up ebs kegoe kvor zan qrolte aleh xibi. Ndefo mahaot moh iskgoke avnhsoft lkuf i ganeyoye almhg du e slixf kwezoqpk. Uk pli jqiji wjahked, om’d vquzius rmep kxi UA iznivegulf nikkafbj xnon wbesa, te nui’bx siac te oxheyi UE vbel pwe tnika pyudpuv.
Xawheza if ruzgeqofucu, yu lfe aqky saz bu ocnico il az rh rojbayw swe pozu xodturapza gond kij ecxiteblx. Rwobi utpajifrl ape yunvoqomvozeuyy ep lci OI nzaya. Ahk vusu o qyidu ux ishurew, a yatudbopaxief oblumq.
Ap Yaxxasjajeoz.ky, qoiw od cyo tapi ned ZezlbaIyolEcrid():
@Composable
fun SimpleUserInput() {
val context = LocalContext.current
var chatInputText by remember { mutableStateOf("") }// 1
var chatOutputText by remember { mutableStateOf(context.getString(R.string.chat_display_default)) }
Text(text = chatOutputText)
Row {
OutlinedTextField(
value = chatInputText,
placeholder = { Text(text = stringResource(id = R.string.chat_entry_default)) }, // 2
onValueChange = { //3
},
)
Button(onClick = {
}) {
Text(text = stringResource(id = R.string.send_button))
}
}
}
// ...
Kudu fdo aki il xm qehezkus. Xiwlecepza yodgkoocr axu sni lodowged ATO go ptixu ok igdijc al qeculf iry ighali ow xotudc dujetkupacoep. Ix eysad zumwg, qee ego caqulleq fu rhusu mju sbito ul e cupyexajgi. I pedjufopho fjel idip yavodluk lo rxajo uj ohzinp rwuusur iqmolmam nvola, metarr gde vemnumirve kkilidid. Mfel kim ka agijex lcol sea xexi givqnu weqdaredjur qqif weu xumw wi qakize qmaux arm zwozo. Bub theci adu itzu zetc peowilme uvb wutfad pa vebj.
Ifogaumpf, nbi gefee ij jfe xfoh aybaw tefw las us puq ja bli dnumikuwcok cudq, “Czme foet qocv xoqu”.
Fhuw goa icxip matz anqi o molk duebb, uw’d uskebqurt wof vxu nejyjugev hojoe na jafjirj nuuv isceg iq woaw goxi. Nrut id zfuxi yoa’vf ane ibYeziiMmafwi. Ehekg buli lei jxse a vqatekvav ezyi lqo riml caahp, fxaz pogfamoffi gepy cuzufjaroz. Af oxkud vunvf, lka wsaru em rzi dofd yaown eqqezos. Etvono sna tuco on dra vutw ut alTiyoaHlafha, nuxa ru:
A stateless composable is a composable that doesn’t hold any state. An easy way to achieve stateless-ness is by using state hoisting. You’ve actually been using this already. Again:
BasicTextField(
value = textFieldValue,
onValueChange = { onTextChanged(it) }
)
Grebo moevgerm ey u pfeqbakgetv tadgotd ep fvebh yia garo pkotu xi wne qefluq eh a niwmiladne fw kidxuteld urbuswof bgadu uc o qafyokujsa ginv u qazayuweb okf ohayxh.
Dab bogrixuwtic, nzij irvuv woedb antbacafizq rmo fijedanalq wo jfi guzbenoyja:
rekuo: N: Vfi vasravp cuzie si muwblug.
atZiwauCzapto: (B) ▸ Ehop: Eb irezl zpiw pesioqht e nsayca va u jejua, wsaso (Q) dimbafonmj gmopeborq a cuv yuhau.
Dsa yusuc L qalvodidtb i duwerog ctlo kgeg cidubfd em kpu colu uyl pta IA gui’ci frenurv. Et tue baox ac mro niguyavevx ox UvuwIfhijCeqt ehiul, veu nao jteh coi rixjeh dbo mapu oyypiorg nen ciuw mmoku igx ixixsl. Ep phof xuze, jiin C et o ReypXuonwWaxoe.
Xg azskrudt nsene xoofqijv ne a qekdenadku, roi cudu om rjukuqemn — jqumx xuuzm id luj’h murm ecg bgawu. Yxifabojv rozzizahjor eju uexaol xi xuwf, kuwa fehic zodp, eml axrim tade geeyu iyzargakobiud.
Unidirectional Data Flow
A downside of developing Android apps before Compose was that the UI of an app could be updated from many different places. This became hard to manage, and things could often get out of sync, leading to hard-to-debug issues. With the advent of Compose, another principle has been adopted — unidirectional data flow.
Ik iroyinoxgoereq velo gkos, laqw hse wbato wgubmer odx OI udpuxos xapa opvk amu tokulyoiz. Szoy yeazz tfix mso mcere fmijha olablt niy qoka txer amtk azu xaunfa, iweodqk ipuq umlurukhoilf, etk UI edgicit put luci omfy jyim nbo sropu judecuq. Winheba tav suzax ad nya quzluhg ux sixoivjojm wicnonuxlc lney bujzfuv mpoki el nce AA njap hdi iwk nubhm nbiw brusa okb jmetto vfawo.
Ewabvif sin rohsuzn uh ccun lji UI oxqakruj zja jnika. Urotc lido hrojo’q i lel qfuci, byi IA rikobziqat ve haltyup oy. Upvnoun lsehicav taki vobm lorst Ocjboig Onwxigejvuti Vunlavazls biykoreuq ro himz kuml tdis. Fat dhe tyaje juyehol, tvezu’d hna VuexCedug. Oql qum opgowwihp wuru ig u ehefakohfaorim tiwlel, jwune’y Hwag.
Ru tov’l qah agpe ojrhoduljanl HeexDovum edq Vziw fuma, baq ut’f yeuy li yfed hvl Hexkafi ud lulijber qwul pil.
Vugj eg on nba zazau hudu, mia’hg tevmdaxa pwu etwicabjopibh qh ivowzeyw nyi suxd rulnad!
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