Programming►Android
Programming

App crash issue when inflating ViewPager

I wrote a very simple layout file with a ViewPager, but the app crashes when inflating it.

Layout file
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<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</FrameLayout>

Here is the error message:

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04-22 22:27:00.828    1128-1479/com.github.timnew.rubiktimer E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.github.timnew.rubiktimer, PID: 1128
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.github.timnew.rubiktimer/com.github.timnew.rubiktimer.history.HistoryActivity_}: android.view.InflateException: Binary XML file line #7: Error inflating class ViewPager
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2282)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2340)
            at android.app.ActivityThread.access$800(ActivityThread.java:157)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5293)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class ViewPager
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:340)
            at com.actionbarsherlock.internal.ActionBarSherlockNative.setContentView(ActionBarSherlockNative.java:134)
            at com.actionbarsherlock.app.SherlockFragmentActivity.setContentView(SherlockFragmentActivity.java:262)
            at com.github.timnew.rubiktimer.history.HistoryActivity_.setContentView(HistoryActivity_.java from OutputFileObject:44)
            at com.github.timnew.rubiktimer.history.HistoryActivity_.onCreate(HistoryActivity_.java from OutputFileObject:34)
            at android.app.Activity.performCreate(Activity.java:5389)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2246)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2340)
            at android.app.ActivityThread.access$800(ActivityThread.java:157)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5293)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.ClassNotFoundException: Didn't find class "android.view.ViewPager" on path: DexPathList[[zip file "/data/app/com.github.timnew.rubiktimer-76.apk"],nativeLibraryDirectories=[/data/app-lib/com.github.timnew.rubiktimer-76, /vendor/lib, /system/lib]]
            at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:67)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
            at android.view.LayoutInflater.createView(LayoutInflater.java:565)
            at android.view.LayoutInflater.onCreateView(LayoutInflater.java:658)
            at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:66)
            at android.view.LayoutInflater.onCreateView(LayoutInflater.java:675)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:700)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:761)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:498)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:398)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:354)
            at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:340)
            at com.actionbarsherlock.internal.ActionBarSherlockNative.setContentView(ActionBarSherlockNative.java:134)
            at com.actionbarsherlock.app.SherlockFragmentActivity.setContentView(SherlockFragmentActivity.java:262)
            at com.github.timnew.rubiktimer.history.HistoryActivity_.setContentView(HistoryActivity_.java from OutputFileObject:44)
            at com.github.timnew.rubiktimer.history.HistoryActivity_.onCreate(HistoryActivity_.java from OutputFileObject:34)
            at android.app.Activity.performCreate(Activity.java:5389)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2246)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2340)
            at android.app.ActivityThread.access$800(ActivityThread.java:157)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5293)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)

According to the message, we can figure out that the issue is caused because Android cannot found the class android.view.ViewPager.

If we’re careful enough, we can figure out that there is something wrong with the ViewPager fullname. Since ViewPager isn’t a standard widget, so it is provided in Support Library instead in the core SDK. So it is not in the package of android.view, it is in the pacakge android.support.v4.view.

To fix the issue, we should not reference the ViewPager with plain name but with the full name android.support.v4.view.ViewPager.

So this is the updated layout xml:

Fixed Lyaout
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<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v4.view.ViewPager
        android:id="@+id/view_pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</FrameLayout>