Question

我一直在尝试将我的片段的导航版本从 2.3.5 升级到 2.4.0-alpha03，以便它可以根据文档支持多个后退堆栈 https://developer.android.com/jetpack/androidx/releases/navigation

并且还帮助保存和恢复我的每个底部导航项目的状态几天，但现在没有成功。每次我同步 build.gradle 中的实现时，我的 homeactivity 中的代码都会抛出此错误 cannot resolve symbol

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

以及它们的导入

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

也抛出错误unused import statement, cannot resolve symbol。因此，如果我运行该应用程序，它就无法执行我想要的上述功能。

这是我迄今为止尝试过的：

我已将此 implementation "androidx.navigation:navigation-fragment:2.4.0-alpha03" and implementation "androidx.navigation:navigation-ui:2.4.0-alpha03" 添加到我的 build.gradle(app)。

但它没有修复。

编辑

我的 Android Gradle 插件版本是 4.0.2

我的 Gradle 版本是 6.1.1

我相信有些事情是我没有做对的，或者是我应该做的事情却没有做。如果有人能识别，我将不胜感激。

这是我的具体代码：

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（项目）：

// 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/colorAccent"
        android:textSize="16sp"
        app:layout_constraintEnd_toStartOf="@+id/imageView4"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/imageView4"
        android:layout_width="50dp"
        android:layout_height="35dp"
        android:layout_marginEnd="1dp"
        android:contentDescription="@string/searchbtn"
        android:src="@drawable/look"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView9"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/time_field"
        android:visibility="gone"
        android:textColor="#FFFFFF"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textfield" />


</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

问题在于您将 2.3.5 导航依赖项与 2.4.0-alpha03 依赖项混合在一起 - 它们都需要完全相同的版本。

您没有使用 Compose，因此您不需要对 navigation-compose 的依赖 - 您应该删除该依赖（如果您也没有使用 Safe Args，也应该删除该依赖）。

相反，您应该只升级现有的导航依赖项：

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

Answer 2

我也在做同样的事情，首先不要使用 2.4.0 alpha-03，因为它们有问题。

从开发者页面复制粘贴

已知问题

在使用 Gradle 6.7.0 时，由于依赖于旧版本的 Kotlin。这可以通过更新以使用 Gradle 7.0 来解决。 (b/190739257)

所以这将在 2.4.0 alpha04 中修复，然后使用 2.4.0 alpha02

所以这不是实际问题尝试降级并使用最新日志更新您的问题，以便我可以帮助您

升级 Fragment 的导航版本时出现问题（从 2.3.5 到 2.4.0-alpha03）

Build.gradle(app):

Build.gradle（项目）：

HomeActivity.java：

Activity_home.xml：

2 个答案: