Android HomeActivity.java上的空指针异常

我在HomeActivity.java上收到一个空指针异常。我无法 能够找到错误

我试图通过

频道用户名

它被放置在

strings.xml

中

LogCat:

D/AndroidRuntime(1695): Shutting down VM
E/AndroidRuntime(1695): FATAL EXCEPTION: main
E/AndroidRuntime(1695): Process: com.grace.view, PID: 1695
E/AndroidRuntime(1695): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.grace.view/com.grace.view.HomeActivity}: java.lang.NullPointerException
E/AndroidRuntime(1695):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
E/AndroidRuntime(1695):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
E/AndroidRuntime(1695):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
E/AndroidRuntime(1695):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
E/AndroidRuntime(1695):     at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(1695):     at android.os.Looper.loop(Looper.java:136)
E/AndroidRuntime(1695):     at android.app.ActivityThread.main(ActivityThread.java:5017)
E/AndroidRuntime(1695):     at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(1695):     at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(1695):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
E/AndroidRuntime(1695):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
E/AndroidRuntime(1695):     at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(1695): Caused by: java.lang.NullPointerException
E/AndroidRuntime(1695):     at com.grace.view.HomeActivity.onCreate(HomeActivity.java:35)
E/AndroidRuntime(1695):     at android.app.Activity.performCreate(Activity.java:5231)
E/AndroidRuntime(1695):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
E/AndroidRuntime(1695):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
E/AndroidRuntime(1695):     ... 11 more

<string name="action_settings">Settings</string>
    <string name="hello_world">Hello world!</string>
    <string-array name="channel_name">
        <item >The Father House</item>

    </string-array>
    <string-array name="channel_username">
        <item >TheJesudian</item>

    </string-array>

HomeActivity.java:

 public class HomeActivity extends FragmentActivity implements ActionBar.OnNavigationListener, VideoListFragment.OnVideoSelectedListener{

    // create object of ActionBar and VideoListFragment
    ActionBar actionBar;
    VideoListFragment videoListFrag;

    int selectedItem;

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

        setContentView(R.layout.activity_home);
        actionBar=getActionBar();

      // add channel list array to actionbar spinner
       Context context = getActionBar().getThemedContext(); ----->Null pointer Exception
       ArrayAdapter<CharSequence> list = ArrayAdapter.createFromResource(context, R.array.channel_name,android.R.layout.simple_spinner_item);
       list.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

     // remove actionbar title and add spinner to actionbar

        getActionBar().setDisplayShowTitleEnabled(false);
        getActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
     // getActionBar().setListNavigationCallbacks(list, this);

    }

    // create option menu
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.home, menu);
        return true;
    }


    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    @Override
    public boolean onNavigationItemSelected(int itemPosition, long itemId) {
        // TODO Auto-generated method stub

        selectedItem = itemPosition;

        // create object of VideoListFragment and send data position to that fragment
        videoListFrag = new VideoListFragment();
        Bundle bundle = new Bundle();
        bundle.putInt("position", itemPosition);
        videoListFrag.setArguments(bundle);

        // call video list fragment with new data
        getFragmentManager()
        .beginTransaction()
        .replace(R.id.content_frame, videoListFrag, "VIDEO_LIST_FRAGMENT")
        .commit();
        return true;
    }

    @Override
    public void onVideoSelected(String ID) {
        // TODO Auto-generated method stub

        // call player page to play selected video
        Intent i = new Intent(HomeActivity.this, PlayerActivity.class);
        i.putExtra("id", ID);
        startActivity(i);

    }

}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.grace.view"
    android:versionCode="6"
    android:versionName="1.3.2" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="19" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.Holo.Light.DarkActionBar" >
        <activity
            android:name="com.grace.view.HomeActivity"
            android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"           
            android:screenOrientation="portrait"
            android:noHistory="true" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity 
            android:name="com.grace.view.PlayerActivity" />

    </application>

</manifest>

公共类HomeActivity扩展碎片Activity实现ActionBar.OnNavigationListener、VideoListFragment.OnVideoSelectedListener{
//创建ActionBar和VideoListFragment的对象
ActionBar ActionBar；
视频列表片段；
int-selectedItem；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_home）；
actionBar=getActionBar（）；
//将频道列表数组添加到actionbar微调器
上下文上下文=getActionBar（）.getThemedContext（）；------>空指针异常
ArrayAdapter list=ArrayAdapter.createFromResource（上下文，R.array.channel\u名称，android.R.layout.simple\u微调器\u项）；
list.setDropDownViewResource（android.R.layout.simple\u微调器\u下拉菜单\u项）；
//删除actionbar标题并将微调器添加到actionbar
getActionBar（）.setDisplayShowTitleEnabled（false）；
getActionBar（）.setNavigationMode（ActionBar.NAVIGATION\u MODE\u列表）；
//getActionBar（）.setListNavigationCallbacks（列表，此）；
}
//创建选项菜单
公共布尔onCreateOptions菜单（菜单）{
getMenuInflater（）.充气（R.menu.home，menu）；
返回true；
}
@TargetApi（构建版本代码蜂窝）
@凌驾
公共布尔值onNavigationItemSelected（int-itemPosition，long-itemId）{
//TODO自动生成的方法存根
选择EdItem=itemPosition；
//创建VideoListFragment的对象并将数据位置发送到该片段
videoListFrag=新的VideoListFragment（）；
Bundle=新Bundle（）；
bundle.putInt（“位置”，itemPosition）；
videoListFrag.setArguments（捆绑）；
//使用新数据调用视频列表片段
getFragmentManager（）
.beginTransaction（）
.替换（R.id.content\u frame，videoListFrag，“VIDEO\u LIST\u FRAGMENT”）
.commit（）；
返回true；
}
@凌驾
已选择公共void onVideoSelected（字符串ID）{
//TODO自动生成的方法存根
//呼叫播放器页面以播放所选视频
意向i=新意向（HomeActivity.this、PlayerActivity.class）；
i、 putExtra（“id”，id）；
星触觉（i）；
}
}

清单：

 public class HomeActivity extends FragmentActivity implements ActionBar.OnNavigationListener, VideoListFragment.OnVideoSelectedListener{

    // create object of ActionBar and VideoListFragment
    ActionBar actionBar;
    VideoListFragment videoListFrag;

    int selectedItem;

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

        setContentView(R.layout.activity_home);
        actionBar=getActionBar();

      // add channel list array to actionbar spinner
       Context context = getActionBar().getThemedContext(); ----->Null pointer Exception
       ArrayAdapter<CharSequence> list = ArrayAdapter.createFromResource(context, R.array.channel_name,android.R.layout.simple_spinner_item);
       list.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

     // remove actionbar title and add spinner to actionbar

        getActionBar().setDisplayShowTitleEnabled(false);
        getActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
     // getActionBar().setListNavigationCallbacks(list, this);

    }

    // create option menu
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.home, menu);
        return true;
    }


    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    @Override
    public boolean onNavigationItemSelected(int itemPosition, long itemId) {
        // TODO Auto-generated method stub

        selectedItem = itemPosition;

        // create object of VideoListFragment and send data position to that fragment
        videoListFrag = new VideoListFragment();
        Bundle bundle = new Bundle();
        bundle.putInt("position", itemPosition);
        videoListFrag.setArguments(bundle);

        // call video list fragment with new data
        getFragmentManager()
        .beginTransaction()
        .replace(R.id.content_frame, videoListFrag, "VIDEO_LIST_FRAGMENT")
        .commit();
        return true;
    }

    @Override
    public void onVideoSelected(String ID) {
        // TODO Auto-generated method stub

        // call player page to play selected video
        Intent i = new Intent(HomeActivity.this, PlayerActivity.class);
        i.putExtra("id", ID);
        startActivity(i);

    }

}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.grace.view"
    android:versionCode="6"
    android:versionName="1.3.2" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="19" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.Holo.Light.DarkActionBar" >
        <activity
            android:name="com.grace.view.HomeActivity"
            android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"           
            android:screenOrientation="portrait"
            android:noHistory="true" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity 
            android:name="com.grace.view.PlayerActivity" />

    </application>

</manifest>

strings.xml:

D/AndroidRuntime(1695): Shutting down VM
E/AndroidRuntime(1695): FATAL EXCEPTION: main
E/AndroidRuntime(1695): Process: com.grace.view, PID: 1695
E/AndroidRuntime(1695): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.grace.view/com.grace.view.HomeActivity}: java.lang.NullPointerException
E/AndroidRuntime(1695):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
E/AndroidRuntime(1695):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
E/AndroidRuntime(1695):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
E/AndroidRuntime(1695):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
E/AndroidRuntime(1695):     at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(1695):     at android.os.Looper.loop(Looper.java:136)
E/AndroidRuntime(1695):     at android.app.ActivityThread.main(ActivityThread.java:5017)
E/AndroidRuntime(1695):     at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(1695):     at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(1695):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
E/AndroidRuntime(1695):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
E/AndroidRuntime(1695):     at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(1695): Caused by: java.lang.NullPointerException
E/AndroidRuntime(1695):     at com.grace.view.HomeActivity.onCreate(HomeActivity.java:35)
E/AndroidRuntime(1695):     at android.app.Activity.performCreate(Activity.java:5231)
E/AndroidRuntime(1695):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
E/AndroidRuntime(1695):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
E/AndroidRuntime(1695):     ... 11 more

<string name="action_settings">Settings</string>
    <string name="hello_world">Hello world!</string>
    <string-array name="channel_name">
        <item >The Father House</item>

    </string-array>
    <string-array name="channel_username">
        <item >TheJesudian</item>

    </string-array>

设置
你好，世界！
父亲之家
耶苏迪亚人

---

任何人都可以帮我。谢谢。

试试

requestWindowFeature（Window.FEATURE\u ACTION\u BAR）

在

setContentView

之前，您正在将主题与NoTitleBar

theme.Black.NoTitleBar.Fullscreen一起使用

将此添加到您的活动中

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if ( keyCode == KeyEvent.KEYCODE_MENU ) {
        // do nothing
        return true;
    }
    return super.onKeyDown(keyCode, event);
}   

您需要删除此行

Context context = getActionBar().getThemedContext(); ----->Null pointer Exception

在适配器类中，只需使用

ArrayAdapter<CharSequence> list = ArrayAdapter.createFromResource(HomeActivity.this, R.array.channel_name,android.R.layout.simple_spinner_item);
list.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

ArrayAdapter list=ArrayAdapter.createFromResource（HomeActivity.this，R.array.channel\u name，android.R.layout.simple\u微调器\u项）；
list.setDropDownViewResource（android.R.layout.simple\u微调器\u下拉菜单\u项）；
HomeActivity的第35行是哪一行？这一行
Context-Context=getActionBar（）.getThemedContext（）我在那里也提到过。@stealthjong如何验证它。它显示空指针异常删除
android:theme=“@android:style/theme.Black.NoTitleBar.Fullscreen”
这一行来自Manifest.xml文件，然后重试again@stealthjong完成后，我只能在debug
08-1903:20:26.697:D/AndroidRuntime（1861）中看到这一行：正在关闭VM
。这对我不起作用。完成此操作后，我再次收到相同的stacktrace错误。我在此行收到一个空指针异常
getActionBar（）。setDisplayShowTitleEnabled（false）
@NarutoShupident如果您需要在家庭活动中使用操作栏，则必须删除此安卓：主题=“@android:style/theme.Black.NoTitleBar.Fullscreen”从清单文件。是的，我尝试了你所说的。删除该行后，我没有得到该异常。但我没有从频道用户名获得视频。输出显示空白，您需要检查您的响应和url是否有数据。检查您传递的视频id是否为空，以及您传递的所有内容的响应和url。如果其中任何一个为空，则无法获取数据。