عرض نتيجة (حسب الحالة)
توضّح هذه الوصفة كيفية عرض نتيجة من شاشة إلى شاشة سابقة باستخدام أسلوب يستند إلى الحالة.
آلية العمل
يستخدم هذا المثال ResultEventBus لإدارة النتيجة كحالة.
- ResultEventBusNavEntryDecorator:
NavEntryDecoratorيوفّرResultEventBusمن خلالLocalResultEventBus. -
ResultEventBus: يتم إنشاءResultEventBusوإتاحته للعناصر القابلة للإنشاء من خلالLocalResultEventBus. يرسل EventBus النتائج ويتلقّاها. - ضبط النتيجة: تستدعي الشاشة التي تنتج النتيجة
resultBus.sendResult(person)لإرسال البيانات مرة أخرى. - مراقبة النتيجة: الشاشة التي تحتاج إلى النتيجة تستدعي
resultBus.conflateAsState<Person?>()للحصول على عنصرStateيمثّل النتيجة. بعد ذلك، تراقب واجهة المستخدم هذه الحالة وتعيد إنشاءها كلما تغيّرت النتيجة.
هذه الطريقة مناسبة عندما تكون النتيجة الأحدث فقط مطلوبة. لا تبقى حالة النتيجة بعد تغيير الإعدادات أو إيقاف العملية.
/* * Copyright 2025 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.example.nav3recipes.results.common import androidx.compose.runtime.getValue import androidx.compose.runtime.mutableStateOf import androidx.compose.runtime.setValue import androidx.lifecycle.ViewModel class HomeViewModel : ViewModel() { var person by mutableStateOf<Person?>(null) }
/* * Copyright 2025 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.example.nav3recipes.results.common import androidx.navigation3.runtime.NavKey import kotlinx.serialization.Serializable @Serializable data object Home : NavKey @Serializable class PersonDetailsForm : NavKey
/* * Copyright 2025 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.example.nav3recipes.results.common import android.os.Parcelable import kotlinx.parcelize.Parcelize @Parcelize data class Person(val name: String, val favoriteColor: String) : Parcelable
/* * Copyright 2025 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.example.nav3recipes.results.common import androidx.compose.foundation.layout.Spacer import androidx.compose.foundation.layout.height import androidx.compose.foundation.text.input.rememberTextFieldState import androidx.compose.material3.Button import androidx.compose.material3.OutlinedTextField import androidx.compose.material3.Text import androidx.compose.runtime.Composable import androidx.compose.ui.Modifier import androidx.compose.ui.unit.dp import androidx.lifecycle.compose.dropUnlessResumed import com.example.nav3recipes.content.ContentBlue import com.example.nav3recipes.content.ContentGreen @Composable fun HomeScreen( person: Person?, onNext: () -> Unit ) { ContentBlue("Hello ${person?.name ?: "unknown person"}") { if (person != null) { Text("Your favorite color is ${person.favoriteColor}") } Spacer(Modifier.height(16.dp)) Button(onClick = dropUnlessResumed(block = onNext)) { Text("Tell us about yourself") } } } @Composable fun PersonDetailsScreen( onSubmit: (Person) -> Unit ) { ContentGreen("About you") { val nameTextState = rememberTextFieldState() OutlinedTextField( state = nameTextState, label = { Text("Please enter your name") } ) val favoriteColorTextState = rememberTextFieldState() OutlinedTextField( state = favoriteColorTextState, label = { Text("Please enter your favorite color") } ) Button( onClick = dropUnlessResumed { val person = Person( name = nameTextState.text.toString(), favoriteColor = favoriteColorTextState.text.toString() ) onSubmit(person) }, enabled = nameTextState.text.isNotBlank() && favoriteColorTextState.text.isNotBlank() ) { Text("Submit") } } }
/* * Copyright 2025 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.example.nav3recipes.results.state import android.os.Bundle import androidx.activity.ComponentActivity import androidx.activity.compose.setContent import androidx.compose.foundation.layout.padding import androidx.compose.material3.Scaffold import androidx.compose.ui.Modifier import androidx.lifecycle.viewmodel.compose.viewModel import androidx.navigation3.runtime.entryProvider import androidx.navigation3.runtime.rememberNavBackStack import androidx.navigation3.runtime.result.LocalResultEventBus import androidx.navigation3.runtime.result.ResultEffect import androidx.navigation3.runtime.result.rememberResultEventBusNavEntryDecorator import androidx.navigation3.ui.NavDisplay import com.example.nav3recipes.results.common.Home import com.example.nav3recipes.results.common.HomeScreen import com.example.nav3recipes.results.common.HomeViewModel import com.example.nav3recipes.results.common.Person import com.example.nav3recipes.results.common.PersonDetailsForm import com.example.nav3recipes.results.common.PersonDetailsScreen import com.example.nav3recipes.ui.setEdgeToEdgeConfig class ResultStateActivity : ComponentActivity() { override fun onCreate(savedInstanceState: Bundle?) { setEdgeToEdgeConfig() super.onCreate(savedInstanceState) setContent { Scaffold { paddingValues -> val backStack = rememberNavBackStack(Home) NavDisplay( backStack = backStack, modifier = Modifier.padding(paddingValues), onBack = { backStack.removeLastOrNull() }, entryDecorators = listOf(rememberResultEventBusNavEntryDecorator()), entryProvider = entryProvider { entry<Home> { val resultState = LocalResultEventBus .current .conflateAsState<Person?>(null) val person = resultState.value HomeScreen( person = person, onNext = { backStack.add(PersonDetailsForm()) } ) } entry<PersonDetailsForm> { val resultBus = LocalResultEventBus.current PersonDetailsScreen( onSubmit = { person -> resultBus.sendResult(result = person) backStack.removeLastOrNull() } ) } } ) } } } }