如何检索和更新Firebase中的特定值

我一直在研究用户通过完成挑战获得奖励的应用程序。目前，用户每完成一项挑战就获得10分。但是我需要这样做，以便每次用户完成挑战时都会更新用户分数，换句话说，这些分数将从数据库中提取并添加额外的分数。（点需要更新，其中userID匹配用户ID）如何检索和更新Firebase中的特定值

我怎么能解决这个问题，谢谢你的任何建议。

public void stopActivity(){ 
    AlertDialog.Builder builder = new AlertDialog.Builder(this); 

    builder.setTitle("Confirm"); 
    builder.setMessage("Are you sure you want to stop?"); 

    builder.setPositiveButton("YES", new DialogInterface.OnClickListener() { 

     public void onClick(DialogInterface dialog, int which) { 

      // Get the activity results 
      String speedText = speedTxt.getText().toString(); 
      String distanceText = distanceTxt.getText().toString(); 
      String timeText = timeTxt.getText().toString(); 

      Toast.makeText(getApplicationContext(),"Your result is: " + "\n" + speedText + "\n" + distanceText + "\n" + timeText, Toast.LENGTH_LONG).show(); 

      //if the result is better 
      if(Double.parseDouble(speed_challege) == Double.parseDouble(speedText) || Double.parseDouble(speed_challege) < Double.parseDouble(speedText)){ 
       Toast.makeText(getApplicationContext(),"You completed the challenge", Toast.LENGTH_LONG).show(); 

       //award points if challenge is completed 
       final DatabaseReference newResult = leaderBoard.push(); 
       String username = mCurrentUser.getEmail(); 

       //trim email leaving just username 
       int index = username.indexOf('@'); 
       username = username.substring(0,index); 

       newResult.child("UserName").setValue(username); 
       newResult.child("uID").setValue(mAuth.getCurrentUser().getUid()); 
       newResult.child("Score").setValue(score); 
      } 

      //if result is worse 
      else{ 
       Toast.makeText(getApplicationContext(),"Hard Luck Try again", Toast.LENGTH_LONG).show(); 
      } 

      dialog.dismiss(); 
     } 
    });

来源

2017-04-07 MariusBrave

你的leaderbord变量引用什么？ –

DatabaseReference mRootRef = FirebaseDatabase.getInstance（）。getReference（）; DatabaseReference leaderBoard = mRootRef.child（“Leaders”）; final DatabaseReference newResult = leaderBoard.push（）; – MariusBrave

您是否添加了有**火力范围内的Java类**？这是

com.firebase.client.Firebase; 
import com.google.firebase.FirebaseApp; 
import com.google.firebase.database.FirebaseDatabase; 


public class `FirebaseContext` extends android.app.Application { 
@Override 
public void onCreate() { 
    super.onCreate(); 
    enter code hereFirebase.setAndroidContext(this); 
    if(!FirebaseApp.getApps(this).isEmpty()){ 
     FirebaseDatabase.getInstance().setPersistenceEnabled(true); 
    } 
    } 
}

来源

2017-04-07 10:51:05

不，我没有？我是不是该？ – MariusBrave

是的，您必须添加此类才能与Firebase连接，它实际上提供了Firebase的上下文 –

如何检索和更新Firebase中的特定值

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