How to search for a specific query on DB with criteria instead of Id

Query Advanced Techniques.java

package com.parse.starter;

import android.content.Intent;
import android.database.Cursor;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;

import com.parse.FindCallback;
import com.parse.GetCallback;
import com.parse.ParseAnalytics;
import com.parse.ParseException;
import com.parse.ParseObject;
import com.parse.ParseQuery;
import com.parse.SaveCallback;

import java.util.List;


public class MainActivity extends AppCompatActivity {

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

      ParseQuery<ParseObject> query = ParseQuery.getQuery("Score");
      query.whereEqualTo("username", "ralphie");     // Look for results with these criteria instead of inserting Id each time.
      query.setLimit(1);  // Only need the first result

      query.findInBackground(new FindCallback<ParseObject>() {
          @Override
          public void done(List<ParseObject> objects, ParseException e) { //Try to find the results on DB and arrange them into A List of ParseObjects

              if (e == null) {

                  if (objects.size() > 0) {

                      objects.get(0).put("score", 250); //Handle the first result and modify the score query value to 250
                      objects.get(0).saveInBackground(); //send data with no Feedback

                  }


              }


          }
      });





    ParseAnalytics.trackAppOpenedInBackground(getIntent());


  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
      return true;
    }

    return super.onOptionsItemSelected(item);
  }
}