Question

SCENARIO

我在fragments内有2 View Pager。在其中一个片段中，我有一个生成通知的按钮。通知已成功生成。现在我想发送一些关于通知的数据点击回到片段。为此我在onNewIntent()中使用activity方法，并从中调用fragment方法将数据传回给片段。

这一切都很好。

问题：

收到通知中的数据后，我将其添加到arraylist并在RecyclerView中显示。现在的主要问题是，在这种情况下，onCreateView()不再被调用，并且由于此问题，片段中的所有视图都为空，这一直导致空指针异常。有没有办法在onResume()中获取视图或保存对先前视图的引用。

以下是相关代码。

活动 onNewIntent（）代码：

@Override
protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    intent=getIntent();
    if (intent.hasExtra("notification_data")) {
        Record record = (Record) intent.getSerializableExtra("notification_data");
        FragmentRecords fragmentRecords = new FragmentRecords();
        fragmentRecords.getDataFromIntent(record);
    }

}

片段 getDataFromIntent 方法：

    public void getDataFromIntent(Record record){

       DatabaseManager databaseManager=new DatabaseManager(MainActivity.context);
       recordDao = null;
       try {
           recordDao=databaseManager.getDao();
           addData();
       } catch (SQLException e) {
           e.printStackTrace();
       }
       recordArrayList.add(record);
       recordAdapter.notifyDataSetChanged();
   }

initView（）方法

private void initView(View view){
    btnAddRecords= (Button) view.findViewById(R.id.btn_add_data);
    btnNotification= (Button) view.findViewById(R.id.btn_create_notification);
    recyclerRecords= (RecyclerView) view.findViewById(R.id.rv_list);
    recordArrayList=new ArrayList<>();
    DatabaseManager databaseManager=new DatabaseManager(MainActivity.context);
    recordDao = null;
    try {
        recordDao=databaseManager.getDao();
        addData();
    } catch (Exception e) {
        e.printStackTrace();
    }

addData（）方法包括将静态数据添加到arraylist中。

private void addData(){
    recordArrayList.add(new Record("Ram","1234567890","10 years","hello",1L));
    recordArrayList.add(new Record("Rahim","1234567890","12 years","hello",2L));
    recordArrayList.add(new Record("Shyam","1234567890","13 years","hello",3L));
    recordArrayList.add(new Record("Sunder","1234567890","40 years","hello",4L));
    recordArrayList.add(new Record("Demo","1234567890","14 years","hello",5L));
    recordArrayList.add(new Record("Demo1","1234567890","15 years","hello",6L));
    recordArrayList.add(new Record("Demo2","1234567890","16 years","hello",7L));
    for (int i=0;i<recordArrayList.size();i++){
        try {
            recordDao.create(recordArrayList.get(i));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    Toast.makeText(MainActivity.context, recordArrayList.size()+" records added successfully", Toast.LENGTH_SHORT).show();
   setAdapter();
}


private void setAdapter(){
       recordAdapter=new RecordAdapter(MainActivity.context,recordArrayList);
       RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(MainActivity.context);
       recyclerRecords.setLayoutManager(mLayoutManager);
       recyclerRecords.setItemAnimator(new DefaultItemAnimator());
       recyclerRecords.addItemDecoration(new SimpleItemDecorator(5));
       recyclerRecords.setAdapter(recordAdapter);


   }

错误Stacktrace

java.lang.NullPointerException：尝试调用虚方法＆＃39; void android.support.v7.widget.RecyclerView.setLayoutManager（android.support.v7.widget.RecyclerView $ LayoutManager）＆＃39;在null对象引用上在com.testdemo.fragments.FragmentRecords.setAdapter（FragmentRecords.java:134）在com.testdemo.fragments.FragmentRecords.addData（FragmentRecords.java:128）在com.testdemo.fragments.FragmentRecords.getDataFromIntent（FragmentRecords.java:148）在com.testdemo.activities.MainActivity.onNewIntent（MainActivity.java:52）在android.app.Instrumentation.callActivityOnNewIntent（Instrumentation.java:1265）在android.app.Instrumentation.callActivityOnNewIntent（Instrumentation.java:1282）在android.app.ActivityThread.deliverNewIntents（ActivityThread.java:2755）在android.app.ActivityThread.performNewIntents（ActivityThread.java:2773）在android.app.ActivityThread.handleNewIntent（ActivityThread.java:2782）在android.app.ActivityThread.-wrap12（ActivityThread.java）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1602）在android.os.Handler.dispatchMessage（Handler.java:111）在android.os.Looper.loop（Looper.java:227）在android.app.ActivityThread.main（ActivityThread.java:6102） at java.lang.reflect.Method.invoke（Native Method）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:961）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:822）

Answer 1

正如评论中指出的那样，您正在与尚未启动的新FragmentRecords实例进行交互，而不是使用现有的片段。您应该尝试检索对现有FragmentRecords实例的引用（如果使用标记来标识您的片段，可能通过findFragmentByTag方法），然后在该实例上调用getDataFromIntent。

我希望它有所帮助。

通知中的片段内的recyclerview添加项目点击

1 个答案: