如何修复实时数据库或活动崩溃

Question

现在，我只是将Firebase实时数据库放入了我的应用程序，每当我打开一个新的Activity包含DatabaseReference时，我的应用程序就会崩溃。有什么建议可以解决这个问题吗？

我遵循了Firebase Realtime Database的教程。网址：https://www.youtube.com/watch?v=EM2x33g4syY&t=3s

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_editor);


     dbr = FirebaseDatabase.getInstance().getReference("title");

    final TableLayout tl = (TableLayout) findViewById(R.id.tbllays);


    String[] teamRoles = {"Director", "Marketing", "Team", "All"};
    final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
    android.R.layout.simple_spinner_dropdown_item, teamRoles);

    context = getApplicationContext();
    //adds new row
    Button addnewrow = (Button) findViewById(R.id.AddRow);
    addnewrow.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //creates table
            final TableRow tbr = new TableRow(context);

            TableRow.LayoutParams layoutParams = new 
            TableRow.LayoutParams(TableRow.LayoutParams.WRAP_CONTENT);
            tbr.setLayoutParams(layoutParams);

            //add edittext to name the task
            EditText editText = new EditText(context);
            editText.setHint("Add Task");
            tbr.addView(editText, 0);

            //add spinner to assign teams
            Spinner toDo = new Spinner(context);
            toDo.setAdapter(adapter);
            tbr.addView(toDo, 1);

            //add spinner to assign teams
            Spinner InProgress = new Spinner(context);
            InProgress.setAdapter(adapter);
            tbr.addView(InProgress, 2);

            //add spinner to assign teams
            Spinner Test = new Spinner(context);
            Test.setAdapter(adapter);
            tbr.addView(Test, 3);

            //add spinner to assign teams
            Spinner Done = new Spinner(context);
            Done.setAdapter(adapter);
            tbr.addView(Done, 4);


            // Add a button in the second column
            Button button = new Button(context);
            button.setText("X");
            tbr.addView(button, 5);
            button.setBackgroundColor(Color.rgb(66, 244, 125));

            // Get delete table row button.
            Button deleteRowButton = (Button) button;
            deleteRowButton.setOnClickListener(new View.OnClickListener() 
{
                @Override
                public void onClick(View v) {
                    tbr.removeAllViews();
                }
            });


            tl.addView(tbr);

        }
    });
    title = (EditText) findViewById(R.id.TitleofDoc);
    createBtn = (Button) findViewById(R.id.SaveThis);
    createBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //AddNewTasks();
        }
    });


}

   private void AddNewTasks() {
    String nitle = title.getText().toString().trim();

    if(!TextUtils.isEmpty(nitle)){
        String id = dbr.push().getKey();

        Title bible = new Title(nitle, id);

        dbr.child(id).setValue(bible);
        Toast.makeText(context, "File Created.", 
   Toast.LENGTH_SHORT).show();
    }else{
        Toast.makeText(context, "Put a Title...", 
   Toast.LENGTH_SHORT).show();
       }


   } 

标题POJO：

 public class Title {
   String title;
   String idon;
   public  Title(){

   } 

   public Title(String title, String idon) {
       this.title = title;
       this.idon = idon;
   }

   public Title(String title) {
       this.title = title;
  } 

   public String getTitle() {
      return title;
   }

   public String getIdon() {
       return idon;
 }
}

错误

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.scrumanager2, PID: 13271
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.scrumanager2/com.example.scrumanager2.MainEditor}: java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process com.example.scrumanager2. Make sure to call FirebaseApp.initializeApp(Context) first.
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
    at android.app.ActivityThread.-wrap12(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6077)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
 Caused by: java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process com.example.scrumanager2. Make sure to call FirebaseApp.initializeApp(Context) first.
    at com.google.firebase.FirebaseApp.getInstance(com.google.firebase:firebase-common@@16.1.0:245)
    at com.google.firebase.database.FirebaseDatabase.getInstance(com.google.firebase:firebase-database@@16.1.0:67)
    at com.example.scrumanager2.MainEditor.onCreate(MainEditor.java:54)
    at android.app.Activity.performCreate(Activity.java:6662)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
    at android.app.ActivityThread.-wrap12(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:154) 
    at android.app.ActivityThread.main(ActivityThread.java:6077) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)