Ni tofauti gani kati ya StatelessWidget na StatefulWidget?

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Flutter ina aina mbili za msingi za widget: **StatelessWidget** (isiyobadilika, bila state ya ndani inayobadilika) na **StatefulWidget** (inaweza kushikilia na kusasisha state inayobadilika, ikijengwa upya state inapobadilika). Kuchagua ile sahihi ni jambo la msingi kwa kujenga UI za Flutter. ## StatelessWidget — bila state inayobadilika ```dart // a StatelessWidget: just describes UI based on its inputs (immutable, no internal state) class Greeting extends StatelessWidget { final String name; const Greeting(this.name); @override Widget build(BuildContext context) { return Text('Hello, $name'); // UI depends only on inputs, never changes itself } } // → use for UI that doesn't change on its own (static content, displays based on inputs) ``` ## StatefulWidget — ina state inayobadilika ```dart // a StatefulWidget: holds STATE that can change → rebuilds the UI when it does class Counter extends StatefulWidget { @override State createState() => _CounterState(); } class _CounterState extends State { int count = 0; // mutable STATE @override Widget build(BuildContext context) { return Column(children: [ Text('Count: $count'), ElevatedButton( onPressed: () => setState(() => count++), // setState → rebuild with new state child: Text('Increment'), ), ]); } } ``` ## setState — ufunguo wa StatefulWidget ```text → setState(() { ... }) tells Flutter the state CHANGED → triggers a REBUILD (build() runs again with the new state, updating the UI) → WITHOUT setState, changing a variable won't update the UI → StatefulWidget = widget config (immutable) + a State object (holds mutable state) ``` ## Kuchagua ```text STATELESS → UI based purely on inputs; doesn't change itself (most widgets; simpler) STATEFUL → needs to hold/change internal state over time (counters, forms, toggles, animations, anything interactive that changes) → Prefer Stateless when possible (simpler); use Stateful when you need changing state. ``` ## Kwa nini ni muhimu Kuelewa tofauti kati ya StatelessWidget na StatefulWidget ni jambo la msingi kwa ukuzaji wa Flutter kwa sababu kuchagua ile sahihi ni muhimu kwa kujenga UI zinazofanya kazi, kwa hivyo ni maarifa ya msingi yanayopaswa kujulikana. Tofauti — **StatelessWidget** (isiyobadilika, ikieleza UI kwa kutegemea kabisa inputs zake, kamwe haibadiliki yenyewe) dhidi ya **StatefulWidget** (ikishikilia state inayobadilika, ikijenga upya UI inapobadilika) — ni mojawapo ya dhana za kwanza na muhimu zaidi katika Flutter, ikiamua jinsi unavyojenga widget yoyote. Kuelewa kwamba **StatelessWidget** inafaa kwa UI isiyobadilika yenyewe (maudhui tuli, maonyesho yanayotegemea inputs — wingi wa widgets, na rahisi zaidi) huku **StatefulWidget** ikihitajika kwa chochote chenye state ya ndani inayobadilika (counters, forms, toggles, vipengele vya kuingiliana) ni muhimu kwa kuchagua kwa usahihi. Kwa umuhimu zaidi, kuelewa **setState** — utaratibu unaoiambia Flutter state imebadilika, ukianzisha rebuild ili UI isasishwe (na kwamba bila huo, kubadilisha kibadilishi hakutasasisha UI, kosa la kawaida sana la wanaoanza) — ni jambo la msingi kufanya StatefulWidgets zifanye kazi. Kuelewa kwamba StatefulWidget inachanganya usanidi wa widget usiobadilika na kitu cha State tofauti kinachoshikilia state inayobadilika hubainisha muundo wake. Mwongozo wa **kupendelea StatelessWidget inapowezekana** (rahisi zaidi) na kutumia StatefulWidget pale tu state inayobadilika inapohitajika unaakisi mazoezi mazuri. Kwa kuwa karibu kila widget ya Flutter unayojenga ni mojawapo ya aina hizi mbili na kuchagua kwa usahihi (na kutumia setState ipasavyo) ni muhimu kwa kujenga UI zinazofanya kazi na zinazoingiliana, kuelewa StatelessWidget dhidi ya StatefulWidget — tofauti yao, lini kutumia kila moja, na jukumu muhimu la setState — ni maarifa muhimu ya msingi ya Flutter, mojawapo ya dhana za msingi zaidi katika ukuzaji wa Flutter ambayo kila mkuzaji wa Flutter lazima aielewe ili kujenga miingiliano ya mtumiaji inayofanya kazi.