java - Problem upgrading my Fragment's Navigation version(from 2.3.5 to 2.4.0-alpha03)

Question

I have been trying to upgrade my fragment's navigation version from 2.3.5 to 2.4.0-alpha03 so that it can support multiple back stacks as per the documentation https://developer.android.com/jetpack/androidx/releases/navigation

and also help in saving and restoring the state of each of my bottom nav items for a few days now unsuccessfully. Each time I sync the implementations in my build.gradle, code in my homeactivity throws this error cannot resolve symbol

final NavController navController = navHostFragment.getNavController(); 
NavigationUI.setupWithNavController(bottomNavigationView, navController);
FirstFragment firstFragment = (FirstFragment) navHostFragment.getChildFragmentManager().getFragments().get(0);

and the imports for them

import androidx.navigation.NavController;
import androidx.navigation.fragment.NavHostFragment;
import androidx.navigation.ui.NavigationUI;

throw an error too unused import statement, cannot resolve symbol. So if I run the app, it's unable to perform the above functions that I want it to.

Here's what i've tried so far:

• I've added this implementation "androidx.navigation:navigation-fragment:2.4.0-alpha03" and implementation "androidx.navigation:navigation-ui:2.4.0-alpha03" to my build.gradle(app).

Yet it didn't fix.

EDIT

My Android Gradle Plugin version is 4.0.2

My Gradle Version is 6.1.1

I believe there's something I didn't do right or something I'm meant to do that I didn't do. Please I'd appreciate it if anyone can identify that.

Here's my specific codes:

Build.gradle(app):

apply plugin: 'com.android.application'

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.2"

    defaultConfig {
        applicationId "com.viz.lightweatherforecast"
        minSdkVersion 21
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

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

dependencies {
    implementation fileTree(dir: "libs", include: ["*.jar"])
    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.3.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
    implementation "androidx.navigation:navigation-fragment:2.4.0-alpha03"
    implementation "androidx.navigation:navigation-ui:2.4.0-alpha03"
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'androidx.media2:media2:1.0.0-alpha04'
    implementation 'org.jetbrains:annotations:15.0'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'

}

Build.gradle(Project):

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:4.0.2"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

HomeActivity.java:

package com.viz.lightweatherforecast.Activity;

import android.media.MediaPlayer;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.navigation.NavController;
import androidx.navigation.fragment.NavHostFragment;
import androidx.navigation.ui.NavigationUI;

import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.viz.lightweatherforecast.FirstFragment;
import com.viz.lightweatherforecast.R;
import com.viz.lightweatherforecast.Retrofit.ApiClient;
import com.viz.lightweatherforecast.Retrofit.ApiInterface;
import com.viz.lightweatherforecast.Retrofit.Example;

import org.jetbrains.annotations.NotNull;

import java.util.Timer;
import java.util.TimerTask;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

public class HomeActivity extends AppCompatActivity {
    // Last update time, click sound, search button, search panel.
    TextView time_field;
    MediaPlayer player;
    ImageView Search;
    EditText textfield;
    // For scheduling background image change(using constraint layout, start counting from dubai, down to statue of liberty.
    ConstraintLayout constraintLayout;
    public static int count=0;
    int[] drawable =new int[]{R.drawable.dubai,R.drawable.central_bank_of_nigeria,R.drawable.eiffel_tower,R.drawable.hong_kong,R.drawable.statue_of_liberty};
    Timer _t;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);
        // use home activity layout.

        time_field = findViewById(R.id.textView9);
        Search = findViewById(R.id.imageView4);
        textfield = findViewById(R.id.textfield);
        //  find the id's of specific variables.

        BottomNavigationView bottomNavigationView = findViewById(R.id.bottomNavigationView);
        // host 3 fragments along with bottom navigation.
        final NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
        assert navHostFragment != null;
        final NavController navController = navHostFragment.getNavController();
        NavigationUI.setupWithNavController(bottomNavigationView, navController);


        // For scheduling background image change
        constraintLayout = findViewById(R.id.layout);
        constraintLayout.setBackgroundResource(R.drawable.dubai);
        _t = new Timer();
        _t.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                // run on ui thread
                runOnUiThread(() -> {
                    if (count < drawable.length) {

                        constraintLayout.setBackgroundResource(drawable[count]);
                        count = (count + 1) % drawable.length;
                    }
                });
            }
        }, 5000, 5000);

        Search.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                // make click sound when search button is clicked.
                player = MediaPlayer.create(HomeActivity.this, R.raw.click);
                player.start();

                getWeatherData(textfield.getText().toString().trim());
                // make use of some fragment's data
                FirstFragment firstFragment = (FirstFragment) navHostFragment.getChildFragmentManager().getFragments().get(0);
                firstFragment.getWeatherData(textfield.getText().toString().trim());

            }

            private void getWeatherData(String name) {

                ApiInterface apiInterface = ApiClient.getClient().create(ApiInterface.class);

                Call<Example> call = apiInterface.getWeatherData(name);

                call.enqueue(new Callback<Example>() {
                    @Override
                    public void onResponse(@NonNull Call<Example> call, @NonNull Response<Example> response) {

                        try {
                            assert response.body() != null;
                            time_field.setVisibility(View.VISIBLE);
                            time_field.setText("Last Updated:" + " " + response.body().getDt());
                        } catch (Exception e) {
                            time_field.setVisibility(View.GONE);
                            time_field.setText("Last Updated: Unknown");
                            Log.e("TAG", "No City found");
                            Toast.makeText(HomeActivity.this, "No City found", Toast.LENGTH_SHORT).show();
                        }
                    }

                    @Override
                    public void onFailure(@NotNull Call<Example> call, @NotNull Throwable t) {
                        t.printStackTrace();
                    }

                });
            }

        });
    }
}

Activity_home.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/layout"
    android:background="@drawable/dubai"
    tools:context=".Activity.HomeActivity">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNavigationView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#FFFFFF"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/bottom_menu" />

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="409dp"
        android:layout_height="599dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@+id/bottomNavigationView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:navGraph="@navigation/my_nav"
        />

    <EditText
        android:id="@+id/textfield"
        android:layout_width="250dp"
        android:layout_height="35dp"
        android:autofillHints="@string/change_city"
        android:background="@color/colorPrimary"
        android:hint="@string/search_city"
        android:inputType="text"
        android:labelFor="@id/imageView4"
        android:padding="8dp"
        android:textColor="@color/colorAcc

Answer 1

The problem is that you're mixing 2.3.5 Navigation dependencies with 2.4.0-alpha03 dependencies - they all need to be exactly the same version.

You aren't using Compose, so you don't need a dependency on navigation-compose - you should remove that dependency (and also the Safe Args one if you are not using Safe Args either).

Instead, you should just upgrade your existing Navigation dependencies:

    implementation "androidx.navigation:navigation-fragment:2.4.0-alpha03"
    implementation "androidx.navigation:navigation-ui:2.4.0-alpha03"