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[英]Why do I get a null pointer exception while passing the data from activity to fragment?
[英]Null Pointer Exception Sending Bundle Data From Activity to Fragment
我正在嘗試將捆綁包數據從活動類發送到片段類,但是我一直在收到NPE錯誤。 我對Stackoverflow進行了一些研究,並嘗試了一些不同的方法,但似乎都沒有效果。
我還有另一個活動類,將意圖發送給MainActivity類。 因此,將MainActivity.java中的捆綁發送給MyFragment類時,絕對不是null。
請幫忙! 謝謝! :D
public class MainActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
Bundle extras = getIntent().getExtras();
if (extras != null) {
Bundle bundle = new Bundle();
String value = extras.getString("TEST36");
bundle.putString("TEST36", value);
MyFragment fragInfo = new MyFragment();
fragInfo.setArguments(bundle);
}
}
}
public class MyFragment extends Fragment{
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_xml, parent, false);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Bundle bundle = getArguments();
String myMode = bundle.getString("TEST36");
}
}
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragment_xml"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:name="com.example.test.MyFragment">
</fragment>
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:id="@+id/TESTINGTV"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="26dp"
android:layout_marginTop="21dp"
android:layout_marginBottom="20dp"
android:textSize="@dimen/text_size" />
</RelativeLayout>
07-12 01:01:59.149: E/AndroidRuntime(2950): FATAL EXCEPTION: main
07-12 01:01:59.149: E/AndroidRuntime(2950): Process: com.example.test, PID: 2950
07-12 01:01:59.149: E/AndroidRuntime(2950): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.MainActivity}: java.lang.NullPointerException
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.ActivityThread.access$800(ActivityThread.java:135)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.os.Handler.dispatchMessage(Handler.java:102)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.os.Looper.loop(Looper.java:136)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.ActivityThread.main(ActivityThread.java:5017)
07-12 01:01:59.149: E/AndroidRuntime(2950): at java.lang.reflect.Method.invokeNative(Native Method)
07-12 01:01:59.149: E/AndroidRuntime(2950): at java.lang.reflect.Method.invoke(Method.java:515)
07-12 01:01:59.149: E/AndroidRuntime(2950): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-12 01:01:59.149: E/AndroidRuntime(2950): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-12 01:01:59.149: E/AndroidRuntime(2950): at dalvik.system.NativeStart.main(Native Method)
07-12 01:01:59.149: E/AndroidRuntime(2950): Caused by: java.lang.NullPointerException
07-12 01:01:59.149: E/AndroidRuntime(2950): at com.example.Fragment.onActivityCreated(MyFragment.java:1098)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1508)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1086)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1884)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:566)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.Activity.performStart(Activity.java:5241)
07-12 01:01:59.149: E/AndroidRuntime(2950): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)
07-12 01:01:59.149: E/AndroidRuntime(2950): ... 11 more
行中的問題
MyFragment fragInfo = new MyFragment();
您正在創建一個新的片段實例,並向其傳遞數據,但是該片段不是UI的一部分。 相反,您可能想通過使用以下內容在UI中找到片段實例
findFragmentById(R.id.my_fragment_id)
在MyFragment fragInfo = new MyFragment();
之后添加以下代碼MyFragment fragInfo = new MyFragment();
fragInfo.setArguments(bundle);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.my_fragment_id, fragInfo);
transaction.commit();
嘗試像這樣在onCreateView
獲取數據
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
String myValue = this.getArguments().getString("TEST36");
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