Android Open Source - Open-Android-Game Location Task

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License

The source code is released under:

GNU General Public License

Java Source Code

/* LocationTask.java - Class for getting location data and doing things with it.
 * //  ww w.j av a 2  s .c om
 * Copyright  2011 Open-Android-Game Group
 * Please see the file COPYING in this
 * distribution for license terms.
 */

package com.kylepaulsen.openAndroidGame;

import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationManager;
import android.widget.Toast;

/*
 * This class is in charge of everything location task related.
 * The first thing it does is generate a random seed from your 
 * last location.
 */

public class LocationTask {
  private Context context;
  private double latitude, longitude; 
  
  public LocationTask(Context con){
    this.context = con;
    
    //just some default values...
    this.latitude = 3000;
    this.longitude = 3000;
  }
  
  /*
   * The init function tries to get the last known location from the best
   * provider. These settings might be changed later.
   * THIS MUST BE CALLED BEFORE ANY OTHER METHOD IN HERE.
   */
  public void init(){
    //I might not be doing something right because the location 
    //data isn't as close as I expected it to be.
    
    LocationManager lm = (LocationManager) this.context.getSystemService(Context.LOCATION_SERVICE);
    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    Location lastLocation = null;
    
    for(int tries=0; tries<3; ++tries){
      String provider = lm.getBestProvider(criteria, true);
      lastLocation = lm.getLastKnownLocation(provider);
      if(lastLocation != null){
        break;
      }
    }
  
    if(lastLocation == null){
      //couldn't get location. send error message or something...
      Toast.makeText(this.context, "Error: Couldn't get last location!", Toast.LENGTH_LONG).show();
      //default to near Salem Oregon.
      this.latitude = 45;
      this.longitude = -123;
    }else{
      this.latitude = lastLocation.getLatitude();
      this.longitude = lastLocation.getLongitude();
    }    
  }
  
  public long makeSeedFromLocation(){
    /*
     * Here is the basic idea for generating a seed:
     * First add 90 to lat and 180 to long to guarantee they are positive.
     * Then multiply both by 100 and then divide by 5. (mult by 20).
     * We mult by 100 because we want to keep up to the hundredth precision
     * out of the lat and long before we floor them.
     * We divide by 5 because we want increments of 5 hundredth's to belong 
     * to the same seed. Then we concatenate the numbers together to get the 
     * seed. Keep in mind that we must multiply the lat_num by 10000 to avoid
     * digit collision during concatenation. (long_num will never be more than 7200)
     */
    if(this.latitude == 3000){
      Toast.makeText(this.context, "LocationTask was used without an init() call.", Toast.LENGTH_LONG).show();
      return 0;
    }
    
    long lat_num = (long) Math.floor((this.latitude+90)*20)*10000;
    long long_num = (long) Math.floor((this.longitude+180)*20);
    Toast.makeText(this.context, "Seed is: "+(lat_num+long_num), Toast.LENGTH_LONG).show();
    return (lat_num+long_num);
  }
  
  public double getLongitude(){
    if(this.longitude == 3000){
      Toast.makeText(this.context, "LocationTask was used without an init() call.", Toast.LENGTH_LONG).show();
      return 0;
    }
    return this.longitude;    
  }
  
  public double getLatitude(){
    if(this.latitude == 3000){
      Toast.makeText(this.context, "LocationTask was used without an init() call.", Toast.LENGTH_LONG).show();
      return 0;
    }
    return this.latitude;    
  }
    
}

Java Source Code List

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