I am trying to call a suspend function using viewModelScope.launch in which "launch" is showing as Unresolved reference.

Here is build.gradle

 plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-kapt'
}

android {
    compileSdk 31

    defaultConfig {
        applicationId "com.example.mynotes"
        minSdk 27
        targetSdk 31
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }

    packagingOptions {
        exclude 'META-INF/atomicfu.kotlin_module'
    }
}

dependencies {
    implementation "androidx.appcompat:appcompat:$rootProject.appCompatVersion"
    implementation "androidx.activity:activity-ktx:$rootProject.activityVersion"

    // Dependencies for working with Architecture components
    // You'll probably have to update the version numbers in build.gradle (Project)

    // Room components
    implementation "androidx.room:room-ktx:$rootProject.roomVersion"
    kapt "androidx.room:room-compiler:$rootProject.roomVersion"
    androidTestImplementation "androidx.room:room-testing:$rootProject.roomVersion"

    // Lifecycle components
    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$rootProject.lifecycleVersion"
    implementation "androidx.lifecycle:lifecycle-livedata-ktx:$rootProject.lifecycleVersion"
    implementation "androidx.lifecycle:lifecycle-common-java8:$rootProject.lifecycleVersion"

    // Kotlin components
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    api "org.jetbrains.kotlinx:kotlinx-coroutines-core:$rootProject.coroutines"
    api "org.jetbrains.kotlinx:kotlinx-coroutines-android:$rootProject.coroutines"

    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.5.0'
    implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.0'

    // UI
    implementation "androidx.constraintlayout:constraintlayout:$rootProject.constraintLayoutVersion"
    implementation "com.google.android.material:material:$rootProject.materialVersion"

    // Testing
    testImplementation "junit:junit:$rootProject.junitVersion"
    androidTestImplementation "androidx.arch.core:core-testing:$rootProject.coreTestingVersion"
    androidTestImplementation ("androidx.test.espresso:espresso-core:$rootProject.espressoVersion", {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    androidTestImplementation "androidx.test.ext:junit:$rootProject.androidxJunitVersion"
}

and the ViewModel.kt

package com.example.mynotes

import android.app.Application
//import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.LiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.*

class NotesViewModel(application: Application) : ViewModel() {

    private val repository : NotesRepository
    val allNotes : LiveData<List<Notes>>

    init {
        val dao = NotesDatabase.getDatabase(application).getNotesDao()
        repository = NotesRepository(dao)
        allNotes = repository.allNotes
    }

    fun deleteNotes(notes: Notes) = viewModelScope.launch(Dispatchers.IO) {
        repository.delete(notes)
    }

}

In the function deleteNotes "viewModelScope.launch" is showing Unresolved reference: launch but there is no error while building the app but my app crash while running.

CodePudding user response：

I think it's because of the way you are declaring the variable, since you are declaring it as a direct function, you can try the following:

fun deleteNotes(notes: Notes) {
    viewModelScope.launch(Dispatchers.IO) {
        repository.delete(notes)
    }
}

It's possible the issue is related that when the method is declared and stored in memory, the scope hasnt been assigned yet.

CodePudding user response：

Which version are you using?

implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.3.1"

Try to use this case is different.

Try to invalide cache and restart if still not recognized