java - Admob 问题 - 无法实例化 fragment com.google.android.gms.$PlaceholderFragment

Question

遵循https://developers.google.com/mobile-ads-sdk/docs/admob/android/quick-start提示 我遇到过 fragment 膨胀的问题。 Google play services lib 添加到 libs/中并作为项目依赖项，还尝试了对 sdk 的外部引用。 Manifest 在 application 标记之上添加了元数据，例如:

    <meta-data
        android:name="com.google.android.gms.version"
        android:value="@integer/google_play_services_version" />

AdFragment 类 在 View 底部的 main_activity View 中设置..:

<RelativeLayout ... >
...
<fragment
        android:id="@+id/adFragment"
        android:name="com.puzzle.activities.MainActivity$AdFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" />
</RelativeLayout>

AdFragment class 放置在 Activity 中:

public static class AdFragment extends Fragment {

    private AdView mAdView;

    public AdFragment() {
    }

    @Override
    public void onActivityCreated(Bundle bundle) {
        super.onActivityCreated(bundle);

        // Gets the ad view defined in layout/ad_fragment.xml with ad unit
        // ID set in
        // values/strings.xml.
        mAdView = (AdView) getView().findViewById(R.id.adView);

        // Create an ad request. Check logcat output for the hashed device
        // ID to
        // get test ads on a physical device. e.g.
        // "Use AdRequest.Builder.addTestDevice("ABCDEF012345") to get test ads on this device."
        AdRequest adRequest = new AdRequest.Builder().addTestDevice(
                AdRequest.DEVICE_ID_EMULATOR).build();

        // Start loading the ad in the background.
        mAdView.loadAd(adRequest);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_admob, container, false);
    }

    /** Called when leaving the activity */
    @Override
    public void onPause() {
        if (mAdView != null) {
            mAdView.pause();
        }
        super.onPause();
    }

    /** Called when returning to the activity */
    @Override
    public void onResume() {
        super.onResume();
        if (mAdView != null) {
            mAdView.resume();
        }
    }

    /** Called before the activity is destroyed */
    @Override
    public void onDestroy() {
        if (mAdView != null) {
            mAdView.destroy();
        }
        super.onDestroy();
    }

}

广告 fragment xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:ads="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <com.google.android.gms.ads.AdView
        android:id="@+id/adView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        ads:adSize="BANNER"
        ads:adUnitId="@string/banner_ad_unit_id" >
    </com.google.android.gms.ads.AdView>

</RelativeLayout>

错误输出是:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.puzzle/com.puzzle.activities.MainActivity_}: android.view.InflateException: Binary XML file line #43: Error inflating class fragment
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2189)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2216)
    at android.app.ActivityThread.access$600(ActivityThread.java:149)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1305)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:153)
    at android.app.ActivityThread.main(ActivityThread.java:5022)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1032)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:790)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: android.view.InflateException: Binary XML file line #43: Error inflating class fragment
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:749)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
    at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:261)
    at android.app.Activity.setContentView(Activity.java:1874)
    at com.puzzle.activities.MainActivity_.setContentView(MainActivity_.java:45)
    at com.puzzle.activities.MainActivity_.onCreate(MainActivity_.java:36)
    at android.app.Activity.performCreate(Activity.java:5032)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2153)
    ... 11 more
Caused by: java.lang.ClassCastException: com.puzzle.activities.MainActivity$AdFragment cannot be cast to android.app.Fragment
    at android.app.Fragment.instantiate(Fragment.java:577)
    at android.app.Fragment.instantiate(Fragment.java:552)
    at android.app.Activity.onCreateView(Activity.java:4680)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:680)
    ... 23 more

欣赏您的想法。

Answer 1

堆栈跟踪状态 ClassCastException:com.xx.activities.MainActivity$AdFragment 无法转换为 android.app.Fragment。但其他地方没有提到这个类。 Activity 布局 XML 中的描述为 android:name="com.puzzle.activities.MainActivity$AdFragment"。请注意封装的差异。

看来您实际上正在 Activity 中加载另一种布局 XML，而不是您向我们展示的布局 XML。检查您的 Activity 的 onCreate。

<小时/>

AdFragment 继承自 Fragment。 Fragment 的导入是什么？

import android.app.Fragment;

或

import android.support.v4.app.Fragment;

我怀疑是后者，加载 fragment 的 Activity 在需要扩展 android.support.v4.app.FragentActivity 时扩展了 android.app.Activity

本质上，您正在将支持类与非支持类结合起来。