Question

我想从一个活动向片段发送一个字符串。这是我在我的活动课中所做的。我从json对象获取字符串并将其发送到片段类。但我作为回应得到了无效。怎么解决这个问题？

 public final static String EXTRA_MESSAGE = "LoginActivity.java";

 JSONObject mainObject2 = new JSONObject(responseStr2);
 String Name = mainObject2.getString("Name");
 Intent i = new Intent(getApplicationContext(),HomeFragment.class);
 Bundle b = new Bundle();
 b.putString("Name", Name);
 i.putExtras(b);
 startActivity(i);

以下是我在片段类中所做的事情。我正在尝试接收字符串并在textview上显示它。

 public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
 View rootView = inflater.inflate(R.layout.fragment_home, container, false);
 String Name = getActivity().getIntent().getStringExtra(LoginActivity.EXTRA_MESSAGE);
 name = (TextView) rootView.findViewById(R.id.name);
 name.setText(Name);

更新1：

我的LogCat显示以下内容。

03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.ActivityThread.access$800(ActivityThread.java:144)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.os.Handler.dispatchMessage(Handler.java:102)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.os.Looper.loop(Looper.java:135)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.ActivityThread.main(ActivityThread.java:5221)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at java.lang.reflect.Method.invoke(Native Method)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at java.lang.reflect.Method.invoke(Method.java:372)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
03-23 13:26:13.756: E/AndroidRuntime(2540): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
03-23 13:26:13.756: E/AndroidRuntime(2540):     at com.webgentechnology.kidskula.HomeFragment.onCreateView(HomeFragment.java:81)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.Fragment.performCreateView(Fragment.java:2053)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:894)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1067)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.BackStackRecord.run(BackStackRecord.java:833)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1452)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.Activity.performStart(Activity.java:5948)
03-23 13:26:13.756: E/AndroidRuntime(2540):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261)
03-23 13:26:13.756: E/AndroidRuntime(2540):     ... 10 more
03-23 13:26:19.086: I/Process(2540): Sending signal. PID: 2540 SIG: 9
03-23 13:26:25.097: I/art(2750): Background partial concurrent mark sweep GC freed 30(3KB) AllocSpace objects, 0(0B) LOS objects, 24% free, 3MB/4MB, paused 11.746ms total 39.506ms
03-23 13:26:26.204: I/art(2750): Background partial concurrent mark sweep GC freed 77(3KB) AllocSpace objects, 0(0B) LOS objects, 20% free, 7MB/9MB, paused 7.144ms total 58.002ms
03-23 13:26:26.726: D/gralloc_goldfish(2750): Emulator without GPU emulation detected.

更新2：

下面是我的XML文件。此布局中有两个选项卡。以下代码是其中一个标签。

 <RelativeLayout
               android:layout_width="fill_parent"
               android:layout_height="wrap_content"
               android:id="@+id/notificationtab"
               android:orientation="vertical"
               android:paddingTop="0dp"  >    

            <Button 
                 android:id="@+id/btn_Delete"
                 android:layout_height="44dp"
                 android:layout_width="78dp"
                 android:text="@string/Archieve"
                 android:textColor="#ffffff"
                 android:layout_marginTop="30dp"
                 android:background="@drawable/custombutton5"
                 android:textSize="18sp"
                 android:layout_marginRight="15dp"
                 android:layout_alignParentRight="true"/>


              <RelativeLayout 
                    android:id="@+id/relative_layout2"
                    android:layout_height="wrap_content"
                    android:layout_width="fill_parent"
                    android:layout_marginTop="90dp">


                 <ListView 
                      android:id="@+id/listView"
                      android:layout_height="wrap_content"
                      android:layout_width="match_parent"
                      android:choiceMode="multipleChoice"> 
                 </ListView>

             </RelativeLayout>

         <CheckBox
              android:id="@+id/chkbox"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_alignBottom="@+id/btn_Retrieve_All_Notification"
              android:layout_alignParentLeft="true"
              android:layout_marginLeft="15dp"
              android:text="@string/CHECK"
              android:textSize="18sp"
              android:textStyle="bold"
              android:textColor="#f33347" />

         <Button
             android:id="@+id/btn_Retrieve_All_Notification"
             android:layout_width="215dp"
             android:layout_height="45dp"
             android:layout_alignBaseline="@+id/btn_Delete"
             android:layout_alignBottom="@+id/btn_Delete"
             android:layout_marginRight="25dp"
             android:layout_toLeftOf="@+id/btn_Delete"
             android:background="@drawable/custombutton5"
             android:text="@string/Retrive"
             android:textColor="#ffffff"
             android:textSize="18sp" />

           </RelativeLayout>

java的引用行如下：

//This is line 81
lst_vw.setAdapter(new Adapterclass(getActivity().getBaseContext()));

解决：

我已使用共享首选项解决了该问题。

Answer 1

您正在使用 startActivity（i）; 来调用Fragment

这是错误的

你应该这样做：

 Bundle b = new Bundle();
 b.putString("Name", Name);
 Fragment startingFragment = getFragmentManager().findFragmentById(R.id.yourfragment);
startingFragment.setArguments(b);
 FragmentTransaction ft = getFragmentManager().beginTransaction();
 ft.add(R.id.yourfragment, startingFragment);
 ft.commit();

这样你可以开始你的片段

然后在片段的onCrateView中，执行以下操作：

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
     View rootView = inflater.inflate(R.layout.fragment_home, container, false);
     String Name = getArguments().getString("Name", 0)
     name = (TextView) rootView.findViewById(R.id.name);
     name.setText(Name);

Answer 2

从数据传递的活动中调用片段

Fragment frag;
Bundle b = new Bundle();
b.putString("Name", Name);
frag.setArguments(b);
                    FragmentManager fm1 = getApplicationContext()
                            .getSupportFragmentManager();
                    FragmentTransaction ft1 = fm1.beginTransaction();
                    frag = new Your_Fragment_Name();


                    ft1.replace(R.id.container, frag);
                    ft1.commit();

在片段类

中接收该字符串

Bundle bundle = getArguments();
        String name = bundle.getString("Name","deafalut_value");

将字符串从一个活动发送到片段

2 个答案: