android - Android Studio，得到 android.view.InflateException 并且找不到任何有效的解决方案

Question

几个小时过去了，我仍然无法绕过这个非常令人沮丧的错误。我是 android 编程的新手，所以我非常关注教程并在我前进的过程中试图理解它们。我也尝试了不同的方法，但不断收到相同的错误。

        java.lang.RuntimeException: Unable to start activity ComponentInfo{com.testapp.scott.mpt/com.testapp.scott.mpt.MyActivity}: android.view.InflateException: Binary XML file line #34: Error inflating class fragment

这是我的片段布局（我使用形状作为背景按钮。这不是问题，因为我已经尝试删除它并且没有任何改变......）

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:layout_height="match_parent"
    tools:context="com.testapp.scott.mpt.MainToolbarFrag"
    android:background="#ff434343">


<Button
    android:layout_width="96dp"
    android:layout_height="fill_parent"
    android:text="My desk"
    android:id="@+id/BT_Toolbar_MyDesk"
    android:background="@drawable/toolbar_buttonbk"
    android:textSize="18sp" />

<Button
    android:layout_width="96dp"
    android:layout_height="fill_parent"
    android:text="Exercises"
    android:id="@+id/BT_Toolbar_Exercises"
    android:background="@drawable/toolbar_buttonbk"
    android:layout_gravity="left"
    android:textSize="18sp" />

<Button
    android:layout_width="96dp"
    android:layout_height="fill_parent"
    android:text="My\nProfile"
    android:id="@+id/BT_Toolbar_MyProfile"
    android:background="@drawable/toolbar_buttonbk"
    android:layout_gravity="left"
    android:textSize="18sp" />

<Button
    android:layout_width="96dp"
    android:layout_height="fill_parent"
    android:text="Extras"
    android:id="@+id/BT_Toolbar_Extras"
    android:background="@drawable/toolbar_buttonbk"
    android:layout_gravity="left"
    android:textSize="18sp" />
</LinearLayout>

我希望在其中显示片段的活动：

<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="horizontal"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MyActivity"
    tools:ignore="MergeRootFrame" >


<Space
    android:layout_width="fill_parent"
    android:layout_height="20dp"
    android:layout_row="0"
    android:layout_column="0"
    android:id="@+id/Space0" />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceMedium"
    android:text="@string/main_welcome"
    android:id="@+id/TV_Main_Welcome"
    android:layout_row="1"
    android:layout_column="0"
    android:textAlignment="center"
    android:singleLine="true"
    android:password="false"
    android:inputType="none"
    android:gravity="center"
    android:textStyle="italic"
    android:layout_gravity="left|top" />

<fragment
    android:layout_width="wrap_content"
    android:layout_height="74dp"
    class="com.testapp.scott.mpt.MainToolbarFrag"
    android:id="@+id/fragment"
    android:layout_row="30"
    android:layout_column="0"
    tools:layout="@layout/fragment_maintoolbar" />

我的片段 Java 类：

package com.testapp.scott.mpt;

import android.app.Activity;
import android.net.Uri;
import android.os.Bundle;
import android.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * A simple {@link Fragment} subclass.
 * Activities that contain this fragment must implement the
 * {@link MainToolbarFrag.OnFragmentInteractionListener} interface
 * to handle interaction events.
 * Use the {@link MainToolbarFrag#newInstance} factory method to
 * create an instance of this fragment.
 *
 */

public class MainToolbarFrag extends Fragment {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment MainToolbarFrag.
     */
    // TODO: Rename and change types and number of parameters
    public static MainToolbarFrag newInstance(String param1, String param2) {
        MainToolbarFrag fragment = new MainToolbarFrag();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }
    public MainToolbarFrag() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_maintoolbar, container, false);
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mListener = (OnFragmentInteractionListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        public void onFragmentInteraction(Uri uri);
    }

}

我的主要活动课程：

package com.testapp.scott.mpt;

import android.app.Activity;
import android.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import com.testapp.scott.mpt.MyClasses.Constants;
import com.testapp.scott.mpt.MyClasses.Exercises;
import com.testapp.scott.mpt.MyClasses.UserData;
import com.testapp.scott.mpt.MyClasses.deskData;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;

import java.io.IOException;
import java.io.InputStream;
import java.text.ParseException;


public class MyActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);
        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment())
                    .commit();


        }
    }

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

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

        public PlaceholderFragment() {
        }

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

最后这是我的日志：

10-13 20:51:54.974    1678-1678/com.testapp.scott.mpt D/dalvikvm﹕ Late-enabling CheckJNI
10-13 20:51:54.994    1678-1684/com.testapp.scott.mpt D/dalvikvm﹕ Debugger has detached; object registry had 1 entries
10-13 20:51:55.074    1678-1678/com.testapp.scott.mpt D/AndroidRuntime﹕ Shutting down VM
10-13 20:51:55.074    1678-1678/com.testapp.scott.mpt W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41941d88)
10-13 20:51:55.074    1678-1678/com.testapp.scott.mpt E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.testapp.scott.mpt, PID: 1678
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.testapp.scott.mpt/com.testapp.scott.mpt.MyActivity}: android.view.InflateException: Binary XML file line #34: Error inflating class fragment
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2237)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2286)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:212)
            at android.app.ActivityThread.main(ActivityThread.java:5135)
            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:877)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.view.InflateException: Binary XML file line #34: Error inflating class fragment
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
            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:297)
            at android.app.Activity.setContentView(Activity.java:1929)
            at com.testapp.scott.mpt.MyActivity.onCreate(MyActivity.java:32)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2201)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2286)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:212)
            at android.app.ActivityThread.main(ActivityThread.java:5135)
            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:877)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.ClassCastException: com.testapp.scott.mpt.MyActivity@44aea5d0 must implement OnFragmentInteractionListener
            at com.testapp.scott.mpt.MainToolbarFrag.onAttach(MainToolbarFrag.java:84)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:853)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1044)
            at android.app.FragmentManagerImpl.addFragment(FragmentManager.java:1146)
            at android.app.Activity.onCreateView(Activity.java:4786)
            at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)
            at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
            at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
            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:297)
            at android.app.Activity.setContentView(Activity.java:1929)
            at com.testapp.scott.mpt.MyActivity.onCreate(MyActivity.java:32)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2201)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2286)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1246)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:212)
            at android.app.ActivityThread.main(ActivityThread.java:5135)
            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:877)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
            at dalvik.system.NativeStart.main(Native Method)

多谢你们！

Answer 1

mListener = (OnFragmentInteractionListener) activity;

这一行有一个ClassCastException。您的活动MyActivity必须实施OnFragmentInteractionListener才能使代码正常工作。