Java getArguments抛出NullPointerException
我在向片段发送值时遇到问题Java getArguments抛出NullPointerException,java,android,nullpointerexception,bundle,Java,Android,Nullpointerexception,Bundle,我在向片段发送值时遇到问题 public class ActivityMain extends ActionBarActivity { int currentPage = 1; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Bundle bundle = ne
public class ActivityMain extends ActionBarActivity {
int currentPage = 1;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Bundle bundle = new Bundle();
textViewPages = (TextView) findViewById(R.id.text_current_page);
if(isOnline()) {
//here will be asyncTask
bundle.putInt("page", currentPage );
fragmentList = new FragmentList();
fragmentList.setArguments(bundle);
fragmentTransaction = getFragmentManager().beginTransaction();
fragmentTransaction.add(R.id.fragment_main, fragmentList);
fragmentTransaction.commit();
}
else {
Toast.makeText(this, getResources().getString(R.string.empty_list), Toast.LENGTH_LONG).show();
}
public boolean isOnline() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo netInfo = cm.getActiveNetworkInfo();
return netInfo != null && netInfo.isConnectedOrConnecting();
}
}
答案可能很简单,但我找不到
public class FragmentList extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
view = inflater.inflate(R.layout.fragment_list, container, false);
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Bundle bundle = getArguments();
currentPage = bundle.getInt("page");
}
getInt()总是抛出NullPointerException,因为它在onActivityCreated或onCreateView中
activity_main.xml
<LinearLayout 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:padding="10dp"
android:orientation="vertical"
tools:context=".MainActivity">
<fragment
android:id="@+id/fragment_main"
android:layout_height="0dp"
android:layout_width="match_parent"
android:layout_weight="0.9"
android:name="com.example.testex.reader.FragmentList"
tools:layout="@layout/fragment_list">
</fragment>
</LinearLayout>
我应该如何更改此代码才能获得!片段中的null bundle?检查片段中的getArguments(),它返回null。您要添加
片段列表两次:
- 它第一次从静态XML扩展而来
- 第二次使用
FragmentTransaction
您添加的第一个FragmentList
没有参数-无法将参数传递给从静态XML膨胀的片段,而引发异常的正是该片段
我怀疑您正在寻找的是将acitvity\u main.xml中的Fragment
标记替换为FrameLayout
tag-FrameLayout
是一个可以容纳动态添加的片段的容器。您能否提供Logcat奇怪的例外情况?到目前为止,您的代码看起来很干净。这些活动和片段中还有其他代码吗?如果有,就贴出来is@Vasiliy完整的代码正在等待advices@Mithun乐意效劳
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="@+id/list_main"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
06-03 23:57:34.355 25337-25337/com.example.testex.reader E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.testex.reader, PID: 25337
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.testex.reader/com.example.testex.reader.ActivityMain}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2359)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2411)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1342)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5323)
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:825)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.testex.reader.FragmentList.onActivityCreated(FragmentList.java:46)
at android.app.Fragment.performActivityCreated(Fragment.java:1708)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:908)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1044)
at android.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1853)
at android.app.Activity.performCreate(Activity.java:5346)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2323)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2411)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1342)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5323)
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:825)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:641)
at dalvik.system.NativeStart.main(Native Method)