java - Android 中 Fragment Activity 出错

Question

我正在按照教程尝试 fragment 应用程序并收到以下错误:

06-28 04:21:47.118: D/AndroidRuntime(1491): Shutting down VM
06-28 04:21:47.128: W/dalvikvm(1491): threadid=1: thread exiting with uncaught exception (group=0xb4af7b90)
06-28 04:21:47.158: E/AndroidRuntime(1491): FATAL EXCEPTION: main
06-28 04:21:47.158: E/AndroidRuntime(1491): Process: com.example.fragmentapp, PID: 1491
06-28 04:21:47.158: E/AndroidRuntime(1491): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fragmentapp/com.example.fragmentapp.MainActivity}: android.view.InflateException: Binary XML file line #8: Error inflating class fragment
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.ActivityThread.access$700(ActivityThread.java:135)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.os.Handler.dispatchMessage(Handler.java:102)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.os.Looper.loop(Looper.java:137)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.ActivityThread.main(ActivityThread.java:4998)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at java.lang.reflect.Method.invokeNative(Native Method)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at java.lang.reflect.Method.invoke(Method.java:515)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at dalvik.system.NativeStart.main(Native Method)
06-28 04:21:47.158: E/AndroidRuntime(1491): Caused by: android.view.InflateException: Binary XML file line #8: Error inflating class fragment
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:290)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.Activity.setContentView(Activity.java:1928)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at com.example.fragmentapp.MainActivity.onCreate(MainActivity.java:13)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.Activity.performCreate(Activity.java:5243)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
06-28 04:21:47.158: E/AndroidRuntime(1491):     ... 11 more
06-28 04:21:47.158: E/AndroidRuntime(1491): Caused by: android.app.Fragment$InstantiationException: Unable to instantiate fragment com.pavan.fragmentdemo.MyListFragment: make sure class name exists, is public, and has an empty constructor that is public
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.Fragment.instantiate(Fragment.java:597)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.Fragment.instantiate(Fragment.java:561)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.Activity.onCreateView(Activity.java:4777)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)
06-28 04:21:47.158: E/AndroidRuntime(1491):     ... 21 more
06-28 04:21:47.158: E/AndroidRuntime(1491): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.pavan.fragmentdemo.MyListFragment" on path: DexPathList[[zip file "/data/app/com.example.fragmentapp-2.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.fragmentapp-2, /system/lib]]
06-28 04:21:47.158: E/AndroidRuntime(1491):     at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
06-28 04:21:47.158: E/AndroidRuntime(1491):     at android.app.Fragment.instantiate(Fragment.java:583)
06-28 04:21:47.158: E/AndroidRuntime(1491):     ... 24 more

代码如下:主Activity.java

package com.example.fragmentapp;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;

public class MainActivity extends Activity implements
        ListFragment.Communicator {

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

    @Override
    public void Message(String OS_Name) {
        DetailFragment detailfragment = (DetailFragment) getFragmentManager()
                .findFragmentById(R.id.detail_Fragment);
        if (detailfragment != null && detailfragment.isInLayout()) {
            detailfragment.setText(OS_Name);
        }
        else {
            Intent intent = new Intent(getApplicationContext(),
                    DetailActivity.class);
            Bundle extras = new Bundle();
            extras.putString(DetailActivity.os_name, OS_Name);
            intent.putExtras(extras);
            startActivity(intent);
        }
    }
}

DetailActivity.java代码

package com.example.fragmentapp;

import android.app.Activity;
import android.content.res.Configuration;
import android.os.Bundle;

public class DetailActivity extends Activity {

    public static String os_name = "";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) {
            finish();
            return;
        }
        setContentView(R.layout.detail_activity);
        Bundle extras = getIntent().getExtras();
        if (extras != null) {
            String name = extras.getString(os_name);
            DetailFragment detailFragment = (DetailFragment) getFragmentManager()
                    .findFragmentById(R.id.detailFragment);
            detailFragment.setText(name);
        }
    }
}

DetailFragment.java代码

package com.example.fragmentapp;

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

public class DetailFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.detail_fragment, container, false);
        return view;
    }

    // we call this method when button from listfragment is clicked
    public void setText(String item) {
        TextView view = (TextView) getView().findViewById(R.id.display_tv);
        view.setText(item);
    }
}

ListFragment.java代码

package com.example.fragmentapp;

import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;

public class ListFragment extends Fragment implements OnClickListener {

    private Communicator communicator;

    Button android_btn, ios_btn, windows_btn;

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        if (activity instanceof Communicator) {
            communicator = (Communicator) activity;
        }
        else {
            throw new
                    ClassCastException(activity.toString()
                    + " must implemenet MyListFragment.Communicator");
        }
    }

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

        // Initialize Views   android_btn = (Button)
        view.findViewById(R.id.android_btn_id);
        ios_btn = (Button)
                view.findViewById(R.id.ios_btn_id);
        windows_btn = (Button)
                view.findViewById(R.id.windows_btn_id);

        // set on click Listeners for buttons  
        android_btn.setOnClickListener(this);
        ios_btn.setOnClickListener(this);
        windows_btn.setOnClickListener(this);

        return view;
    }

    //Create Interface   
    public interface Communicator {
        public void Message(String OS_Name);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.android_btn_id:
                updateFragment("Android");
                break;
            case R.id.ios_btn_id:
                updateFragment("IOS");
                break;

            case R.id.windows_btn_id:
                updateFragment("Windows");
                break;
        }
    }

    private void updateFragment(String OS_Name) {
        communicator.Message(OS_Name);
    }
}

在布局文件夹中Activity_main.xml

<?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:orientation="horizontal" >

    <fragment
        android:id="@+id/list_Fragment"
        android:layout_width="0sp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        class="com.pavan.fragmentdemo.MyListFragment" >
    </fragment>

    <fragment
        android:id="@+id/detail_Fragment"
        android:layout_width="0sp"
        android:layout_height="match_parent"
        android:layout_weight="2"
        class="com.pavan.fragmentdemo.DetailFragment" >
    </fragment>

</LinearLayout>

detail_fragment.xml代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FFFF99"
    android:orientation="vertical"
    android:padding="20dp" >

    <TextView
        android:id="@+id/display_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:textSize="40sp" />

</LinearLayout>

list_fragment.xml代码

<?xml version="1.0" encoding="utf-8"?> <LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#CCFF99"
    android:orientation="vertical"
    android:padding="5dp" >

    <Button
        android:id="@+id/android_btn_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Android" />

    <Button
        android:id="@+id/ios_btn_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="IOS" />

    <Button
        android:id="@+id/windows_btn_id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Windows" />

</LinearLayout>

在布局端口中代码activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <fragment
        android:id="@+id/list_Fragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        class="com.pavan.fragmentdemo.MyListFragment" >
    </fragment>

</LinearLayout>

detail_activity.xml代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <fragment
        android:id="@+id/detailFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        class="com.pavan.fragmentdemo.DetailFragment" />

</LinearLayout>

Answer 1

您有不同的 fragment 名称:在 xml com.pavan.fragmentdemo.MyListFragment 中在 java com.example.fragmentapp.MyListFragment

修复包名称