无法启动活动ComponentInfo：android.view.InflateException：二进制XML文件第7行：错误膨胀类片段

问题描述 投票：0回答：3

在 Android Studio 中尝试 Fragments 时出现以下错误。启动应用程序时出现以下异常：

04 - 24 21: 02: 16.830 21108 - 21108 / com.example.user.samplefragments E / AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo {
    com.example.user.samplefragments / com.example.user.samplefragments.MainActivity
}: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
                                                                                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2245)
                                                                                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2299)
                                                                                      at android.app.ActivityThread.access$700(ActivityThread.java:150)
                                                                                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
                                                                                      at android.os.Handler.dispatchMessage(Handler.java:99)
                                                                                      at android.os.Looper.loop(Looper.java:137)
                                                                                      at android.app.ActivityThread.main(ActivityThread.java:5283)
                                                                                      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:1102)
                                                                                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
                                                                                      at dalvik.system.NativeStart.main(Native Method)
                                                                                   Caused by: android.view.InflateException: Binary XML file line # 7: Error inflating class fragment
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java: 710)
at android.view.LayoutInflater.rInflate(LayoutInflater.java: 752)
at android.view.LayoutInflater.inflate(LayoutInflater.java: 495)
at android.view.LayoutInflater.inflate(LayoutInflater.java: 397)
at android.view.LayoutInflater.inflate(LayoutInflater.java: 353)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java: 364)
at android.app.Activity.setContentView(Activity.java: 1930)
at com.example.user.samplefragments.MainActivity.onCreate(MainActivity.java: 19)
at android.app.Activity.performCreate(Activity.java: 5283)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java: 1097)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2209)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java: 2299) 
at android.app.ActivityThread.access$700(ActivityThread.java: 150) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1280) 
at android.os.Handler.dispatchMessage(Handler.java: 99) 
at android.os.Looper.loop(Looper.java: 137) 
at android.app.ActivityThread.main(ActivityThread.java: 5283) 
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: 1102) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 869) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException
at com.example.user.samplefragments.MenuFragment.onCreateView(MenuFragment.java: 23)
at android.app.Fragment.performCreateView(Fragment.java: 1699)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java: 879)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java: 1053)
at android.app.FragmentManagerImpl.addFragment(FragmentManager.java: 1155)
at android.app.Activity.onCreateView(Activity.java: 4872)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java: 686)
at android.view.LayoutInflater.rInflate(LayoutInflater.java: 752) 
at android.view.LayoutInflater.inflate(LayoutInflater.java: 495) 
at android.view.LayoutInflater.inflate(LayoutInflater.java: 397) 
at android.view.LayoutInflater.inflate(LayoutInflater.java: 353) 
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java: 364) 
at android.app.Activity.setContentView(Activity.java: 1930) 
at com.example.user.samplefragments.MainActivity.onCreate(MainActivity.java: 19) 
at android.app.Activity.performCreate(Activity.java: 5283) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java: 1097) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java: 2209) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java: 2299) 
at android.app.ActivityThread.access$700(ActivityThread.java: 150) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java: 1280) 
at android.os.Handler.dispatchMessage(Handler.java: 99) 
at android.os.Looper.loop(Looper.java: 137) 
at android.app.ActivityThread.main(ActivityThread.java: 5283) 
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: 1102) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java: 869) 
at dalvik.system.NativeStart.main(Native Method) 

这是我的 MainActivity.java :

package com.example.user.samplefragments;

import android.app.Activity;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.FragmentActivity;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends Activity implements MenuFragment.OnItemSelectedListener{

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


    }

    @Override
    public void onItemSelected(String link) {
        DetailFragment fragment = (DetailFragment)getFragmentManager().findFragmentById(R.id.detailfragment);
        fragment.setText(link);

    }
}



This is my Fragment 1 :

package com.example.user.samplefragments;

import android.app.Fragment;
import android.content.Context;
import android.os.Bundle;
import android.provider.Settings;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

/**
 * Created by USER on 24-04-2016.
 */
public class MenuFragment extends Fragment{
    private OnItemSelectedListener listener;
    public MenuFragment(){}
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.menu,container,false);
        Button btn = (Button)getView().findViewById(R.id.button);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                updateDetail("fake");
            }
        });
        return view;
    }
    public void updateDetail(String uri){

        String newTime = String.valueOf(System.currentTimeMillis());
        listener.onItemSelected(newTime);

    }

    public interface OnItemSelectedListener {
        public void onItemSelected(String link);
    }

}


This is my Fragment 2 :

package com.example.user.samplefragments;

import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/**
 * Created by USER on 24-04-2016.
 */
public class DetailFragment extends Fragment{
    public DetailFragment(){}
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.detail,container,false);
        return view;
    }
    public void setText(String url){

        TextView tv = (TextView)getView().findViewById(R.id.textView);
        tv.setText(url);
    }

}


This is my activity_main.xml :

Just using two fragments inside the main layout.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:baselineAligned="false"
    android:orientation="horizontal" >
    <fragment
      android:id="@+id/menufragment"
        class="com.example.user.samplefragments.MenuFragment" /**Declaring the class of the fragment*/
        android:layout_height="match_parent"
        android:layout_width="5dp">
    </fragment>
    <fragment
        android:id="@+id/detailfragment"
        class="com.example.user.samplefragments.DetailFragment" 
        android:layout_height="match_parent"
        android:layout_width="5dp">
    </fragment>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New Button"
        android:id="@+id/button2" />

</LinearLayout>

如您所见，我收到的错误：

java.lang.RuntimeException：无法启动活动 ComponentInfo{com.example.user.samplefragments/com.example.user.samplefragments.MainActivity}：android.view.InflateException：二进制 XML 文件第 #7 行：膨胀类片段时出错。

我知道当包名称错误时会出现此问题，但我已经给出了正确的包名称。我该如何解决这个问题？

android android-fragments
3个回答
1
投票

解决方案：

您可以使用以下方法修改您的

MenuFragment
：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.menu, container, false);
    Button btn = (Button)view.findViewById(R.id.button);
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            updateDetail("fake");
        }
    });
    return view;
}

为什么：

每次调用 

onCreateView
时，fragment 中的视图即将创建。此时您的fragment 中还没有视图。因此 
getView()
始终返回 
onCreateView
中调用的 null。这就是为什么在 xml 中膨胀片段时会出现 
NullPointerException
。

要避免 NullPointer，请尝试以下操作：

public void updateDetail(String uri){
    String newTime = String.valueOf(System.currentTimeMillis());
    if ( listener != null ){
        listener.onItemSelected(newTime);
    }
}
0
投票

我认为这条线会使应用程序崩溃，

Button btn = (Button)getView().findViewById(R.id.button);

将此行替换为 

Button btn = (Button)view.findViewById(R.id.button);

如果您的按钮包含在片段 xml (R.layout.menu) 中，它将起作用。

0
投票

请分享您的活动 xml 布局代码。 膨胀片段时存在一些问题。

请不要忘记将 

android:name
属性设置为您的片段路径

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