Question

我正在学习Android，当它们处于不同的风格时，我找不到片段实例化错误的解决方案。

设定：

我有一个加载到主要活动中的主片段。
我有两个好处：付费和免费。
应用程序的主要（常见）部分没有片段（布局+ java文件），我将它们放入好处。

当我尝试运行程序时出现以下错误：

01-24 19:38:06.211 27417-27417/com.udacity.gradle.builditbigger.paid E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.udacity.gradle.builditbigger.paid, PID: 27417
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.udacity.gradle.builditbigger.paid/com.udacity.gradle.builditbigger.MainActivity}: android.view.InflateException: Binary XML file line #1: Binary XML file line #1: Error inflating class fragment
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2817)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
    at android.app.ActivityThread.-wrap11(Unknown Source:0)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
    at android.os.Handler.dispatchMessage(Handler.java:105)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6541)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: android.view.InflateException: Binary XML file line #1: Binary XML file line #1: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #1: Error inflating class fragment
Caused by: java.lang.NullPointerException
    at java.lang.VMClassLoader.findLoadedClass(Native Method)
    at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:738)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:363)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
    at android.support.v4.app.Fragment.isSupportFragmentClass(Fragment.java:499)
    at android.support.v4.app.FragmentManagerImpl.onCreateView(FragmentManager.java:3637)
    at android.support.v4.app.FragmentController.onCreateView(FragmentController.java:111)
    at android.support.v4.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:338)
    at android.support.v4.app.BaseFragmentActivityApi14.onCreateView(BaseFragmentActivityApi14.java:39)
    at android.support.v4.app.FragmentActivity.onCreateView(FragmentActivity.java:67)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:780)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
    at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287)
    at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139)
    at com.udacity.gradle.builditbigger.MainActivity.onCreate(MainActivity.java:14)
    at android.app.Activity.performCreate(Activity.java:6975)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1213)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2770)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2892)
    at android.app.ActivityThread.-wrap11(Unknown Source:0)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1593)
    at android.os.Handler.dispatchMessage(Handler.java:105)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6541)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

我尝试了许多不同版本的片段名称，因为错误消息告诉我问题与此有关，遗憾的是它们都没有工作。能帮我找到问题的原因（我的意思不仅仅是解决方案，还有为什么这不起作用）？ The code can be found on GitHub，但相关文件在这里：

SRC / JAVA / COM / udacity / gradle这个/ builditbigger / MainActivity.java

package com.udacity.gradle.builditbigger;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

public void tellJoke(View view) {
    new EndpointsAsyncTask().execute(this);
}
}

的src / RES /布局/ activity_main.xml中

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="@layout/fragment_main" />

的src /免费/ JAVA / COM / udacity / gradle这个/ builditbigger /免费/ MainActivityFragment.java

package com.udacity.gradle.builditbigger.free;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.udacity.gradle.builditbigger.R;


/**
 * A placeholder fragment containing a simple view.
 */
public class MainActivityFragment extends Fragment {

public MainActivityFragment() {
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View root = inflater.inflate(R.layout.fragment_main, container, false);

    AdView mAdView = (AdView) root.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();
    mAdView.loadAd(adRequest);
    return root;
}
}

的src /免费/ RES /布局/ fragment_main.xml

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.udacity.gradle.builditbigger.MainActivity">

<TextView
    android:id="@+id/instructions_text_view"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/instructions" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/instructions_text_view"
    android:onClick="tellJoke"
    android:text="@string/button_text" />

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

</RelativeLayout>

SRC /付费/ JAVA / COM / udacity / gradle这个/ builditbigger /付费/ MainActivityFragment.java

package com.udacity.gradle.builditbigger.paid;

import android.support.v4.app.Fragment;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.udacity.gradle.builditbigger.R;


/**
 * A placeholder fragment containing a simple view.
 */
public class MainActivityFragment extends Fragment {

public MainActivityFragment() {
}

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

SRC /付费/ RES /布局/ fragment_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.udacity.gradle.builditbigger.MainActivity">

<TextView
    android:id="@+id/instructions_text_view"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/instructions" />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/instructions_text_view"
    android:onClick="tellJoke"
    android:text="@string/button_text" />

</RelativeLayout>

Answer 1

与此同时，我找到了解决方案。在src/res/layout/activity_main.xml中，您需要为片段提供android:name属性才能使其正常工作。两种名称（MainActivityFragment）的名称相同，但名称空间不同（free和paid）。解决此问题的唯一方法是您需要将此布局文件移动到应用程序的flavor部分，并从主要部分删除原始文件。简而言之，您必须删除src/res/layout/activity_main.xml文件，并将这两个文件添加到项目中：

<强>的src /免费/ RES /布局/ activity_main.xml中

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/fragment"
android:name="com.udacity.gradle.builditbigger.free.MainActivityFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="@layout/fragment_main" />

<强> SRC /付费/ RES /布局/ activity_main.xml中

<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/fragment"
android:name="com.udacity.gradle.builditbigger.paid.MainActivityFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout="@layout/fragment_main" />

我很抱歉原来的问题，但我希望它对某人有用。

从不同的口味片段膨胀

1 个答案: