不可转换的类型； 无法将“android.support.v4.app.Fragment”转换为“com.google.android.gms.maps.SupportMapFragment”

Question

我已经创建了一个谷歌地图的活动，那就是当错误弹出时，在活动的构建完成后就会出现错误。 错误是：

 Inconvertible types; cannot cast 'android.support.v4.app.Fragment' to 'com.google.android.gms.maps.SupportMapFragment'

在行中（在 MapsActivity 中）：

SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager() .findFragmentById(R.id.map);

而且我还在资源中输入了API密钥！！

进口：

import android.support.v4.app.FragmentActivity;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

显现：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.purabjain.memorableplaces">

    <!--
         The ACCESS_COARSE/FINE_LOCATION permissions are not required to use
         Google Maps Android API v2, but you must specify either coarse or fine
         location permissions for the 'MyLocation' functionality.
    -->
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        tools:replace="android:appComponentFactory"
        android:appComponentFactory="whateverString">

        <!--
             The API key for Google Maps-based APIs is defined as a string resource.
             (See the file "res/values/google_maps_api.xml").
             Note that the API key is linked to the encryption key used to sign the APK.
             You need a different API key for each encryption key, including the release key that is used to
             sign the APK for publishing.
             You can define the keys for the debug and release targets in src/debug/ and src/release/.
        -->
        <meta-data
            android:name="com.google.android.geo.API_KEY"
            android:value="@string/google_maps_key" />

        <activity
            android:name=".MapsActivity"
            android:label="@string/title_activity_maps"></activity>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

构建.gradle：

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.purabjain.memorableplaces"
        minSdkVersion 21
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.google.android.gms:play-services-maps:17.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

地图活动：

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapsActivity extends FragmentActivity  implements OnMapReadyCallback {

    private GoogleMap mMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }


    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    @Override
    public void onMapReady(GoogleMap googleMap) {
       /* mMap = googleMap;

        // Add a marker in Sydney and move the camera
        LatLng sydney = new LatLng(-34, 151);
        mMap.addMarker(new MarkerOptions().position(sydney).title("Marker in Sydney"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(sydney));*/
    }
}

api.xml：

    <!--
    TODO: Before you run your application, you need a Google Maps API key.

    To get one, follow this link, follow the directions and press "Create" at the end:

    https://console.developers.google.com/flows/enableapi?apiid=maps_android_backend&keyType=CLIENT_SIDE_ANDROID&r=E6:56:90:82:E2:58:42:66:59:4C:5A:F2:E5:9B:64:06:EC:1E:05:49%3Bcom.purabjain.memorableplaces

    You can also add your credentials to an existing key, using these values:

    Package name:
    E6:56:90:82:E2:58:42:66:59:4C:5A:F2:E5:9B:64:06:EC:1E:05:49

    SHA-1 certificate fingerprint:
    E6:56:90:82:E2:58:42:66:59:4C:5A:F2:E5:9B:64:06:EC:1E:05:49

    Alternatively, follow the directions here:
    https://developers.google.com/maps/documentation/android/start#get-key

    Once you have your key (it starts with "AIza"), replace the "google_maps_key"
    string in this file.
    -->
    <string name="google_maps_key" templateMergeStrategy="preserve" translatable="false">AIzaSyDaCq_mx5h741VnM-4tNkNmQiT70yf7ykw</string>
</resources>

Answer 1

我也为这个问题而苦苦挣扎，但事实证明，新版的Google地图使用的AndroidX版本为17.0.0。 所以你应该使用16.1.0

所以改变这个：

implementation 'com.google.android.gms:play-services-maps:17.0.0'

对此：

implementation 'com.google.android.gms:play-services-maps:16.1.0'

另外，请确保您没有使用任何使用AndroidX的应用：在我的情况下，我使用了这会造成麻烦：

implementation 'com.google.android.gms:play-services-location:17.0.0'

所以我也这么做了

implementation 'com.google.android.gms:play-services-location:16.0.0'

这是版本列表； https://mvnrepository.com/artifact/com.google.android.gms/play-services-maps

正确版本的Google Play服务： https ： //developers.google.com/android/guides/releases

Answer 2

将它们添加到build.gradle（Module：app）文件中：

androidTestImplementation 'androidx.test:runner:1.2.0'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

Answer 3

我在'androidx.fragment.app.fragment' 到 'com.google.android.gms.maps.supportmapfragment'有类似的问题，解决方案是更改谷歌地图的版本。

从：

implementation 'com.google.android.gms:play-services-maps:16.0.0'

到：

implementation 'com.google.android.gms:play-services-maps:17.0.0'