Java Firebase数据库无法获取值

试图访问的数据：

如果我在我的应用程序中选择“腹胀”和“腹泻”的值，那么它应该在文本视图中显示“痉挛”和“无法控制的肠道综合征”作为输出。获取这种情况下的值的函数是readDataListenerForTwo（）。如何更正代码

sympleActivity.java

package com.example.nishantsikri.microdoctor;

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.Spinner;
import android.widget.TextView;

import android.widget.Toast;

import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import java.security.SecurityPermission;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;


public class SymptomActivity extends AppCompatActivity {


static boolean calledAlready = false;
Integer i = 2;
private DatabaseReference mFirebaseDatabase, spinnerDatabase;
private FirebaseDatabase mFirebaseInstance;
Button button,add_button,sub_button;
TextView textView,symptom1,symptom2,symptom3;
Spinner spinner,spinner2,spinner3;
String textSymptom1,textSymptom2,textSymptom3;

@Override
public void onBackPressed() {
    startActivity(new Intent(getApplicationContext(),NavigationActivity.class));
    finish();
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_symptom);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    button = (Button) findViewById(R.id.button8);
    add_button = (Button) findViewById(R.id.add_button);
    sub_button = (Button) findViewById(R.id.sub_button);
    textView = (TextView) findViewById(R.id.textView2);

    symptom1 = (TextView) findViewById(R.id.symptom1);
    symptom2 = (TextView) findViewById(R.id.symptom2);
    symptom3 = (TextView) findViewById(R.id.symptom3);
    spinner = (Spinner) findViewById(R.id.spinner1);
    spinner2 = (Spinner) findViewById(R.id.spinner2);
    spinner3 = (Spinner) findViewById(R.id.spinner3);

    spinner3.setEnabled(false);
    spinner3.setVisibility(View.GONE);
    symptom3.setVisibility(View.GONE);
    sub_button.setEnabled(false);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    if (!calledAlready)
    {
        FirebaseDatabase.getInstance().setPersistenceEnabled(true);
        calledAlready = true;
    }


    // Write a message to the database
    mFirebaseInstance = FirebaseDatabase.getInstance();
    // store app title to 'app_title' node
    mFirebaseInstance.getReference("app_title").setValue("microDoctor");
    mFirebaseDatabase = mFirebaseInstance.getReference("symptomList");
    spinnerDatabase = mFirebaseInstance.getReference("symptomView");
    //mFirebaseDatabase.child("Headache").child("Some Value").setValue("Head");
    //mFirebaseDatabase.setValue("Headache");


    spinnerData();
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
            textSymptom1 = spinner.getItemAtPosition(i).toString();
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });
    spinner2.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
            textSymptom2 = spinner2.getItemAtPosition(i).toString();
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });
    spinner3.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
            textSymptom3 = spinner3.getItemAtPosition(i).toString();
        }

        @Override
        public void onNothingSelected(AdapterView<?> adapterView) {

        }
    });

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if(i == 3)
                readDataListener();
            else
                readDataListenerForTwo();
        }
    });
    add_button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            spinner3.setEnabled(true);
            spinner3.setVisibility(View.VISIBLE);
            symptom3.setVisibility(View.VISIBLE);
            add_button.setEnabled(false);
            sub_button.setEnabled(true);
            i++;
            Log.e("Value i","Value of i: "+i);
        }
    });
    sub_button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            spinner3.setEnabled(false);
            spinner3.setVisibility(View.GONE);
            symptom3.setVisibility(View.GONE);
            add_button.setEnabled(true);
            sub_button.setEnabled(false);
            i--;
            Log.e("Value i","Value of i: "+i);
        }
    });

}

private void readDataListener() {
      mFirebaseDatabase.child(textSymptom1).child(textSymptom2).child(textSymptom3).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String symptom = dataSnapshot.child("disease").getValue(String.class);

            // Check for null
            if (symptom == null) {
                Log.e("Data", "Symptom data is null!");
                return;
            }

            Log.e("Symptom Data", "User data is changed!"+symptom);

            // Display newly updated name and email
            textView.setText(symptom+"\n"+dataSnapshot.getKey());
            Intent intent = new Intent(getApplicationContext(),DiseaseActivity.class);
            intent.putExtra("key", symptom);
            startActivity(intent);
        }

        @Override
        public void onCancelled(DatabaseError error) {
            // Failed to read value
            Log.e("Error", "Failed to read user", error.toException());
        }
    });
}
private void readDataListenerForTwo(){
        mFirebaseDatabase.child(textSymptom1).child(textSymptom2).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String symptom = dataSnapshot.getValue(String.class);

            // Check for null
            if (symptom == null) {
                Log.e("Data", "Symptom data is null!");
                Log.e("Chutiya","Haila! Chutiya run ho ra hai! ._.");
                return;
            }

            Log.e("Symptom Data", "User data is changed!"+symptom);


            // Display newly updated name and email
//                textView.setText(symptom+"\n"+dataSnapshot.getKey());
//                Intent intent = new Intent(getApplicationContext(),DiseaseActivity.class);
//                intent.putExtra("key", symptom);
//                startActivity(intent);
        }

        @Override
        public void onCancelled(DatabaseError error) {
            // Failed to read value
            Log.e("Error", "Failed to read user", error.toException());
        }
    });
}
private void spinnerData() {
    spinnerDatabase.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            Log.e("Spinner Data", "Spinner data is changed!");

            //DataSnapshot data = dataSnapshot;
            Iterable<DataSnapshot> temp = dataSnapshot.getChildren();
            ArrayList<String> list = new ArrayList<>();
//                list.add(dataSnapshot.getValue().toString());
//                showDataInSpinner(list);
            for (DataSnapshot lists : temp){
                Log.d("ddd","Array List: "+lists.getValue().toString());
                list.add(lists.getValue().toString());
                textView.setText(lists.getValue().toString());
            }
            showDataInSpinner(list);

        }

        @Override
        public void onCancelled(DatabaseError error) {
            // Failed to read value
            Log.e("Error", "Failed to read user", error.toException());
        }
    });
}
public void showDataInSpinner(ArrayList<String> data) {
    ArrayAdapter<String> adapter = new ArrayAdapter<>(
            this, android.R.layout.simple_spinner_item, data
    ); //Create the Adapter to set the data
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);     //Set the layout resource to create the drop down views.
    spinner.setAdapter(adapter); //Set the data to your spinner
    spinner2.setAdapter(adapter);
    spinner3.setAdapter(adapter);
}
}

---

要在

下获取这些名称，请使用以下代码：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference diarrheaRef = rootRef.child("symptomList").child("Bloating").child("Diarrhea");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String name = ds.getKey();
            Log.d("TAG", name);
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
diarrheaRef.addListenerForSingleValueEvent(eventListener);

您的输出将是：

Cramps
Uncontrollable Bowel Syndrome

您需要一个字符串，但需要一张地图。你有没有试着记录地图上的内容，看看你到底得到了什么？亚历克斯给出了正确的答案
Cramps
Uncontrollable Bowel Syndrome