README.md

+## Ackee android test task
+This test task that was written based on the following description: https://github.com/AckeeCZ/android-task-rick-and-morty#readme.
+In this project, I used the Compose toolkit for defining the UI layer and Coroutines for handling asynchronous tasks. It is the first time I have used these libraries in a project.
+Normally, I use default XML layouts and RxJava. You can find an example of my "study" e-shop application with XML/RxJava on https://gitlab.fel.cvut.cz/barysole/pda-sw-e-shop.
+
+The application uses the modern Material Design 3 component library, and because of that, some elements look different from the design. I have decided that it is not a problem for this test task.
+
+## APPLICATION APK
+
+
+## KNOWING ISSUES
+- Problem: The characters list doesn't save its scrolling position after navigating to the character detail screen and back.
+Analysis: LazyColumn gets the characters list from the ViewModel flow by using the ".collectAsLazyPagingItems()" method, and this method retrieves only part of the characters list after navigation.
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app/src/main/java/cz/fel/barysole/ackeetesttask/MainActivity.kt

@@ -51,7 +51,8 @@ class MainActivity : ComponentActivity() {
 fun navigate(
     navController: NavController,
     currentScreen: MutableState<Screen>,
-    nextScreen: Screen, args: List<Any>?
+    nextScreen: Screen, args: List<Any>?,
+    isSearchBarShowing: MutableState<Boolean>
 ) {
     if (nextScreen != currentScreen.value) {
         if (nextScreen == Screen.Characters || nextScreen == Screen.Favorite) {
@@ -71,6 +72,7 @@ fun navigate(
             navController.navigateUp()
         }
     }
+    isSearchBarShowing.value = false
 }
 
 @Composable
@@ -121,7 +123,7 @@ fun MainScreen() {
     // onScreenSelected perform all navigation in the app
     val onSelectScreen = remember {
         { screen: Screen, args: List<Any>? ->
-            navigate(navController, selectedScreen, screen, args)
+            navigate(navController, selectedScreen, screen, args, isSearchBarShowing)
         }
     }
 

app/src/main/java/cz/fel/barysole/ackeetesttask/repository/characters/CharacterRepositoryImpl.kt

@@ -10,6 +10,8 @@ import cz.fel.barysole.ackeetesttask.db.room.AppDatabase
 import cz.fel.barysole.ackeetesttask.db.room.dao.CharacterDao
 import cz.fel.barysole.ackeetesttask.model.CharacterInfo
 import kotlinx.coroutines.flow.Flow
+import retrofit2.HttpException
+import java.io.IOException
 import javax.inject.Inject
 import javax.inject.Singleton
 
@@ -58,9 +60,15 @@ class CharacterRepositoryImpl @Inject constructor(
     }
 
     override suspend fun getCharacter(characterId: Long): CharacterInfo? {
-        val response = rickAndMortyApi.getCharacterById(characterId)
-        appDatabase.withTransaction {
-            insertCharacterItems(listOf(response), appDatabase.characterDao())
+        try {
+            val response = rickAndMortyApi.getCharacterById(characterId)
+            appDatabase.withTransaction {
+                insertCharacterItems(listOf(response), appDatabase.characterDao())
+            }
+        } catch (exception: IOException) {
+            //todo: add exception handling
+        } catch (exception: HttpException) {
+            //todo: add exception handling
         }
         return appDatabase.characterDao().getById(characterId)
     }

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/Screen.kt

@@ -34,7 +34,8 @@ sealed class Screen(
         "characterdetail/{characterId}",
         routeWithoutArgument = "characterdetail",
         actionList = listOf(ScreenAction.AddToFavoriteScreenAction),
-        showBottomBar = false
+        showBottomBar = false,
+        isBackButtonShowing = true
     )
 }
 

app/src/main/java/cz/fel/barysole/ackeetesttask/ui/screen/characterlist/CharacterListScreen.kt

@@ -12,6 +12,8 @@ import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
@@ -30,43 +32,43 @@ fun CharacterListScreen(
     Surface(
         color = MaterialTheme.colorScheme.background
     ) {
-        characterListViewModel.charactersPDFlow.collectAsLazyPagingItems().let {
-            if (it.loadState.mediator?.refresh is LoadState.Error || it.loadState.mediator?.append is LoadState.Error) {
-                characterListViewModel.showLoadingError(true)
-            } else {
-                characterListViewModel.showLoadingError(false)
+        val characterItems = characterListViewModel.charactersPDFlow.collectAsLazyPagingItems()
+        if (characterItems.loadState.source.append is LoadState.Error) {
+            characterListViewModel.showLoadingError(true)
+        } else {
+            characterListViewModel.showLoadingError(false)
+        }
+        // If the UI state contains an error, show snackbar
+        val characterListScreenState by characterListViewModel.uiState.collectAsState()
+        if (characterListScreenState.showError) {
+            val errorMessage = stringResource(R.string.data_cannot_be_loaded_error)
+            LaunchedEffect(snackbarHostState) {
+                snackbarHostState.showSnackbar(
+                    message = errorMessage
+                )
             }
-            // If the UI state contains an error, show snackbar
-            if (characterListViewModel.uiState.value.showError) {
-                val errorMessage = stringResource(R.string.data_cannot_be_loaded_error)
-                LaunchedEffect(snackbarHostState) {
-                    snackbarHostState.showSnackbar(
-                        message = errorMessage
+        }
+        // todo: there is no pullToRefresh in MD3 at this moment. Add it later. :c
+        if (characterItems.itemCount == 0 && characterItems.loadState.refresh != LoadState.Loading) {
+            Column(
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .fillMaxHeight(),
+                verticalArrangement = Arrangement.Center,
+                horizontalAlignment = Alignment.CenterHorizontally
+            ) {
+                Button(
+                    onClick = { characterListViewModel.refreshList() },
+                    colors = ButtonDefaults.buttonColors(
+                        containerColor = MaterialTheme.colorScheme.surface,
+                        contentColor = MaterialTheme.colorScheme.primary
                     )
-                }
-            }
-            // todo: there is no pullToRefresh in MD3 at this moment. Add it later. :c
-            if (it.itemCount == 0 && it.loadState.refresh != LoadState.Loading) {
-                Column(
-                    modifier = Modifier
-                        .fillMaxWidth()
-                        .fillMaxHeight(),
-                    verticalArrangement = Arrangement.Center,
-                    horizontalAlignment = Alignment.CenterHorizontally
                 ) {
-                    Button(
-                        onClick = { characterListViewModel.refreshList() },
-                        colors = ButtonDefaults.buttonColors(
-                            containerColor = MaterialTheme.colorScheme.surface,
-                            contentColor = MaterialTheme.colorScheme.primary
-                        )
-                    ) {
-                        Text(stringResource(R.string.reload_text))
-                    }
+                    Text(stringResource(R.string.reload_text))
                 }
-            } else {
-                CharacterList(it, onSelectItem)
             }
+        } else {
+            CharacterList(characterItems, onSelectItem)
         }
     }
 }
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app/src/main/java/cz/fel/barysole/ackeetesttask/ui/uielement/charactersearch/MySearchBar.kt

@@ -45,7 +45,9 @@ fun MySearchBar(
         characterSearchViewModel.onFieldClean()
     }
     SearchBar(
-        modifier = Modifier.padding(if (isSearchBarIsActive.value) 0.dp else 8.dp),
+        modifier = Modifier
+            .fillMaxWidth(1f)
+            .padding(if (isSearchBarIsActive.value) 0.dp else 8.dp),
         query = searchBarState.query,
         onQueryChange = { characterSearchViewModel.onCharacterSearch(it) },
         onSearch = { characterSearchViewModel.onCharacterSearch(it) },
@@ -77,31 +79,30 @@ fun MySearchBar(
         tonalElevation = 0.dp,
         colors = if (isSearchBarIsActive.value) SearchBarDefaults.colors(containerColor = MaterialTheme.colorScheme.background) else SearchBarDefaults.colors()
     ) {
-        characterSearchViewModel.pagingDataFlow.collectAsLazyPagingItems().let {
-            // do not show elements when the query is empty
-            if (searchBarState.query.isNotBlank()) {
-                if (it.loadState.refresh is LoadState.Error) {
-                    Box(
-                        modifier = Modifier
-                            .fillMaxWidth(1f)
-                            .padding(vertical = 64.dp),
-                        contentAlignment = Alignment.Center
-                    ) {
-                        Text(
-                            stringResource(R.string.data_cannot_be_loaded_error),
-                            style = MaterialTheme.typography.titleMedium,
-                            textAlign = TextAlign.Center
-                        )
-                    }
-                } else {
-                    CharacterList(it) { characterId ->
-                        onSelectScreen(
-                            Screen.CharacterDetail,
-                            listOf(characterId)
-                        )
-                    }
+        val characterListItems = characterSearchViewModel.pagingDataFlow.collectAsLazyPagingItems()
+        // do not show elements when the query is empty
+        if (searchBarState.query.isNotBlank()) {
+            if (characterListItems.loadState.refresh is LoadState.Error) {
+                Box(
+                    modifier = Modifier
+                        .fillMaxWidth(1f)
+                        .padding(vertical = 64.dp),
+                    contentAlignment = Alignment.Center
+                ) {
+                    Text(
+                        stringResource(R.string.data_cannot_be_loaded_error),
+                        style = MaterialTheme.typography.titleMedium,
+                        textAlign = TextAlign.Center
+                    )
+                }
+            } else {
+                CharacterList(characterListItems) { characterId ->
+                    onSelectScreen(
+                        Screen.CharacterDetail,
+                        listOf(characterId)
+                    )
                 }
             }
         }
     }
-}
+}
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