Develop Reference

onSimulatorDataUpdated() not getting called

private void initFlightController() {
DJIAircraft aircraft = DJISimulatorApplication.getAircraftInstance();
if (aircraft == null || !aircraft.isConnected()) {
log("initFlightController: aircraft not connected");
showToast("Disconnected");
mFlightController = null;
return;
} else {
log("initFlightController: aircraft CONNECTED");
mFlightController = aircraft.getFlightController();
DJISimulator djiSimulator = mFlightController.getSimulator();
log("initFlightController: djiSimulator has started : "+djiSimulator.hasSimulatorStarted());
djiSimulator.setUpdatedSimulatorStateDataCallback(new DJISimulator.UpdatedSimulatorStateDataCallback() {
#Override
public void onSimulatorDataUpdated(final DJISimulatorStateData djiSimulatorStateData) {
log("onSimulatorDataUpdated: ");
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
String yaw = String.format("%.2f", djiSimulatorStateData.getYaw());
String pitch = String.format("%.2f", djiSimulatorStateData.getPitch());
String roll = String.format("%.2f", djiSimulatorStateData.getRoll());
String positionX = String.format("%.2f", djiSimulatorStateData.getPositionX());
String positionY = String.format("%.2f", djiSimulatorStateData.getPositionY());
String positionZ = String.format("%.2f", djiSimulatorStateData.getPositionZ());
mTextView.setText("Yaw : " + yaw + ", Pitch : " + pitch + ", Roll : " + roll + "\n" + ", PosX : " + positionX +
", PosY : " + positionY +
", PosZ : " + positionZ);
}
});
}
});
}
}
I am testing the sample code given for android in Dji-Developer. Every thing goes fine but the onSimulatorDataUpdated() doesnt get called.
it even prints the log
"initFlightController: djiSimulator has started : true"

I found the solution for the problem. The code doesn't have any problem, the RC has a button at the left front area which has to be set to P mode.

Remove previous route in graphhopper android?

I am using graphhopper and mapsforge to show the route in my android app.The route is shown in my mapView from the polyline but when I change the location of second point the new route is shown above the previous route.So I need to delete this previous route when a new route is calculated. The code is as follows:
GraphHopper localGraphHopper = new GraphHopper().forMobile();
localGraphHopper.setCHShortcuts(true, true);
localGraphHopper.load(getFolderPath());
GHRequest localGHRequest = new GHRequest(paramDouble1, paramDouble2, paramDouble3, paramDouble4);
GHRequest a = localGHRequest.setAlgorithm("dijkstrabi");
GHResponse localGHResponse = localGraphHopper.route(localGHRequest);
int i = localGHResponse.getPoints().getSize();
PointList localPointList = localGHResponse.getPoints();
Polyline localPolyline = new Polyline(createPaint(AndroidGraphicFactory.INSTANCE.createColor(Color.RED), 4, Style.STROKE), AndroidGraphicFactory.INSTANCE);
this.latLongs_track = localPolyline.getLatLongs();
for (int j = 0;; j++)
{
if (j >= i)
{
this.mapView.getLayerManager().getLayers().add(localPolyline);
LatLong localLatLong = new LatLong((paramDouble1 + paramDouble3) / 2.0D, (paramDouble2 + paramDouble4) / 2.0D);
this.mapView.getModel().mapViewPosition.setCenter(localLatLong);
return;
}
this.latLongs_track.add(new LatLong(localPointList.getLatitude(j), localPointList.getLongitude(j)));
}

Use this function:
public void calcPath( final double fromLat, final double fromLon,
final double toLat, final double toLon ) {
log("calculating path ...");
new AsyncTask<Void, Void, GHResponse>(){
float time;
protected GHResponse doInBackground( Void... v ){
StopWatch sw = new StopWatch().start();
GHRequest req = new GHRequest(fromLat, fromLon, toLat, toLon).
setAlgorithm(AlgorithmOptions.DIJKSTRA_BI);
req.getHints().
put("instructions", "false");
GHResponse resp = hopper.route(req);
time = sw.stop().getSeconds();
return resp;
}
protected void onPostExecute( GHResponse resp ){
if (!resp.hasErrors()){
log("from:" + fromLat + "," + fromLon + " to:" + toLat + ","
+ toLon + " found path with distance:" + resp.getDistance()
/ 1000f + ", nodes:" + resp.getPoints().getSize() + ", time:"
+ time + " " + resp.getDebugInfo());
logUser("the route is " + (int) (resp.getDistance() / 100) / 10f
+ "km long, time:" + resp.getMillis() / 60000f + "min, debug:" + time);
mapView.getLayerManager().getLayers().add(createPolyline(resp));
//mapView.redraw();
} else{
logUser("Error:" + resp.getErrors());
}
shortestPathRunning = false;
}
}.execute();
}
All source you can find at https://github.com/graphhopper/graphhopper

I have found the answer for my problem and am posting here
Polyline localPolyline;
public void calcPath( final double fromLat, final double fromLon,
final double toLat, final double toLon )
{
log("calculating path ...");
new AsyncTask<Void, Void, GHResponse>()
{
float time;
protected GHResponse doInBackground( Void... v )
{
StopWatch sw = new StopWatch().start();
GHRequest req = new GHRequest(fromLat, fromLon, toLat, toLon).
setAlgorithm(AlgorithmOptions.DIJKSTRA_BI);
req.getHints()
.put("instructions", "false");
GHResponse resp = hopper.route(req);
time = sw.stop().getSeconds();
return resp;
}
protected void onPostExecute( GHResponse resp )
{
if (!resp.hasErrors())
{
if(localPolyline!=null){
mapView.getLayerManager().getLayers().remove(localPolyline);
}
else{
log("here");
}
log("from:" + fromLat + "," + fromLon + " to:" + toLat + ","
+ toLon + " found path with distance:" + resp.getDistance()
/ 1000f + ", nodes:" + resp.getPoints().getSize() + ", time:"
+ time + " " + resp.getDebugInfo());
logUser("the route is " + (int) (resp.getDistance() / 100) / 10f
+ "km long, time:" + resp.getMillis() / 60000f + "min, debug:" + time);
localPolyline=createPolyline(resp);
mapView.getLayerManager().getLayers().add(localPolyline);
} else
{
logUser("Error:" + resp.getErrors());
}
}
}.execute();
}
Thanks to everybody.

String Equation parser issue

I'm coding a method that solve various kind of equation. Now I want that the method receives a String equation that could be in the forms:
ax^2+bx+c=0
or
*ax^2+c=0*
or
bx+c=0
etc. and the order shouldn't matter.
My problem is: How could I parse the equation according the "x" grade?
The eq could contains more values of the same grade for example 2x^2+4x^2+3x+8=2 (max grade x^3).
My method should assign the a value to double a[] if on the left or on the right of a there is x^2, double b[], if on the left or on the right there is x, and double c[] if there isn't any x variable near the value (and should change the value sign if the therms is after the =).
Convert a String number in a double is simple but I don't know how I could disassemble the input String according the x grade as described.

Tested for -2x + 3x^2 - 2 + 3x = 3 - 2x^2
public Double[] parseEquation(String equation)
{
Log.d(TAG, "equation: " + equation);
// Remove all white spaces
equation = equation.replaceAll("[ ]", "");
// Get the left and right sides of =
String[] sides = equation.split("[=]"); // should be of size 2
boolean leftNegative = false;
boolean rightNegative = false;
if (sides.length != 2)
{
// There is no = or more than one = signs.
}
else
{
// if sides i starts with + remove the +
// if - we remove and put it back later
for (int i = 0; i < 2; i++)
{
if (sides[i].charAt(0) == '+')
{
sides[i] = sides[i].substring(1);
}
}
if (sides[0].charAt(0) == '-')
{
leftNegative = true;
sides[0] = sides[0].substring(1);
}
if (sides[1].charAt(0) == '-')
{
rightNegative = true;
sides[1] = sides[1].substring(1);
}
}
Log.d(TAG, "left side:" + sides[0] + " right side: " + sides[1]);
// Terms without signs need to find out later
String[] leftTerms = sides[0].split("[+-]");
String[] rightTerms = sides[1].split("[+-]");
int length = leftTerms[0].length();
if (leftNegative)
{
leftTerms[0] = "-" + leftTerms[0];
}
// put in the minus sign for the rest of the terms
for (int i = 1; i < leftTerms.length; i++)
{
Log.d(TAG, "length = " + length + " " + sides[0].charAt(length));
if (sides[0].charAt(length) == '-')
{
leftTerms[i] = "-" + leftTerms[i];
length += leftTerms[i].length();
}
else
{
length += leftTerms[i].length() + 1;
}
}
length = rightTerms[0].length();
if (rightNegative)
{
rightTerms[0] = "-" + rightTerms[0];
}
for (int i = 1; i < rightTerms.length; i++)
{
Log.d(TAG, "length = " + length + " " + sides[1].charAt(length));
if (sides[1].charAt(length) == '-')
{
rightTerms[i] = "-" + rightTerms[i];
length += rightTerms[i].length();
}
else
{
length += rightTerms[i].length() + 1;
}
}
// Now we put all the factors and powers in a list
List<ContentValues> leftLists = new ArrayList<ContentValues>();
// left side
for (int i = 0; i < leftTerms.length; i++)
{
Log.d(TAG, "leftTerm: " + leftTerms[i]);
ContentValues contentValues = new ContentValues();
int indexOfX = leftTerms[i].indexOf('x');
if (indexOfX == -1)
{
// no x mean a constant term
contentValues.put("factor", leftTerms[i]);
contentValues.put("power", "0");
}
else
{
int indexOfHat = leftTerms[i].indexOf('^');
if (indexOfHat == -1)
{
// no hat mean power = 1
contentValues.put("power", "1");
String factor = leftTerms[i].substring(0, indexOfX).trim();
contentValues.put("factor", factor);
}
else
{
String power = leftTerms[i].substring(indexOfX + 2).trim();
String factor = leftTerms[i].substring(0, indexOfX).trim();
contentValues.put("factor", factor);
contentValues.put("power", power);
}
}
Log.d(TAG, contentValues.toString());
leftLists.add(contentValues);
}
List<ContentValues> rightLists = new ArrayList<ContentValues>();
for (int i = 0; i < rightTerms.length; i++)
{
Log.d(TAG, "rightTerm: " + rightTerms[i]);
ContentValues contentValues = new ContentValues();
int indexOfX = rightTerms[i].indexOf('x');
if (indexOfX == -1)
{
// no hat mean a constant term
contentValues.put("factor", rightTerms[i]);
contentValues.put("power", "0");
}
else
{
int indexOfHat = rightTerms[i].indexOf('^');
if (indexOfHat == -1)
{
// no hat mean power = 1
contentValues.put("power", "1");
String factor = rightTerms[i].substring(0, indexOfX).trim();
contentValues.put("factor", factor);
}
else
{
String power = rightTerms[i].substring(indexOfX + 2).trim();
String factor = rightTerms[i].substring(0, indexOfX).trim();
contentValues.put("factor", factor);
contentValues.put("power", power);
}
}
Log.d(TAG, contentValues.toString());
rightLists.add(contentValues);
}
// Now add the factors with same powers.
// Suppose we solve for cubic here the end result will be
// 4 terms constant, x, x^2 and x^3
// Declare a double array of dim 4 the first will hold constant
// the second the x factor etc...
// You can allow arbitrary power by looping through the lists and get the max power
Double[] result = new Double[]{0.0, 0.0, 0.0, 0.0};
for (ContentValues c : leftLists)
{
switch (c.getAsInteger("power"))
{
case 0:
//Log.d(TAG, "power = 0, factor = " + c.toString());
result[0] += c.getAsDouble("factor");
break;
case 1:
result[1] += c.getAsDouble("factor");
break;
case 2:
result[2] += c.getAsDouble("factor");
break;
case 3:
result[3] += c.getAsDouble("factor");
break;
}
}
for (ContentValues c : rightLists)
{
switch (c.getAsInteger("power"))
{
case 0:
//Log.d(TAG, "power = 0, factor = " + c.toString());
result[0] -= c.getAsDouble("factor");
break;
case 1:
result[1] -= c.getAsDouble("factor");
break;
case 2:
result[2] -= c.getAsDouble("factor");
break;
case 3:
result[3] -= c.getAsDouble("factor");
break;
}
}
Log.d(TAG, "constant term = " + result[0] + ", x^1 = " + result[1]
+ ", x^2 = " + result[2] + ", x^3 = " + result[3]);
return result;
}

If you weren't limited by Android, I'd suggest using a lexer and parser. These are code generators, so they can work anywhere the base language works, but they tend to produce bloated code. Android might not appreciate that.

Garbage Collector slowing down the application when iterating the arraylist

I use the following code to convert elements from ArrayList to string:
public static List<Location> GPSLocalLocations = new ArrayList<Location>(1);
String mystr = "";
for (int i=0; i<GPSService.GPSLocalLocations.size(); i++)
{
mystr += "\n" + GPSService.GPSLocalLocations.get(i).toString();
}
Changed my code to the following:
for (int i=0; i<GPSService.GPSLocalLocations.size(); i++)
{
gpslog.append("\n").append(GPSService.GPSLocalLocations.get(i).toString());
}
It causes less GC Free messages :). My mistake, application didn't hang because of that... I think because I ran a my ASyncTask multiple times...
But still iterating ArrayList of more than 1000 elements takes some time [about 10 seconds]. Is that ok?

I'd recommend to use StringBuilder.
From here http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.2_r1.1/android/location/Location.java#Location.toString%28%29 :
#Override public String [More ...] toString() {
return "Location[mProvider=" + mProvider +
",mTime=" + mTime +
",mLatitude=" + mLatitude +
",mLongitude=" + mLongitude +
",mHasAltitude=" + mHasAltitude +
",mAltitude=" + mAltitude +
",mHasSpeed=" + mHasSpeed +
",mSpeed=" + mSpeed +
",mHasBearing=" + mHasBearing +
",mBearing=" + mBearing +
",mHasAccuracy=" + mHasAccuracy +
",mAccuracy=" + mAccuracy +
",mExtras=" + mExtras + "]";
}
I'd recommend write it yourself in following way:
public static List<Location> GPSLocalLocations = new ArrayList<Location>(1);
StringBuilder gpslog = new StringBuilder();
for (int i=0; i<GPSService.GPSLocalLocations.size(); i++)
{
Location location = GPSService.GPSLocalLocations.get(i);
gpslog.append("\n")
.append("Location[Provider=").append(location.getProvider(())())
.append(",Time=").append(location.getTime())
.append(",Latitude=").append(location.getLatitude())
.append(",Longitude=").append(location.getLongitude())
.append(",HasAltitude=").append(location.getHasAltitude())
.append(",Altitude=").append(location.getAltitude())
.append(",HasSpeed=").append(location.getHasSpeed())
.append(",Speed=").append(location.getSpeed())
.append(",HasBearing=").append(location.getHasBearing())
.append(",Bearing=").append(location.getBearing())
.append(",HasAccuracy=").append(location.getHasAccuracy())
.append(",Accuracy=").append(location.getAccuracy())
.append(",Extras=").append(location.getExtras()).append("]");
}

JSON remove special characters

I want to do the replication between Android sqlite & MS SQL server.That Time i want to take Tables values from Databse.
This is my JSON
{
"Table1":[
{
"BusinessUnit":"MASS",
"ProductCode":"SLD0201",
"Description":"Lou Difan C.Blue 12"3- Commode",
"Description2":"301 0201"
},
{
"BusinessUnit":"MASS",
"ProductCode":"SLN0502",
"Description":"Lou Napoli I"vory- Cistern",
"Description2":"2011 0502"
},
{
"BusinessUnit":"MASS",
"ProductCode":"LDMBL6H",
"Description":"Dortek Taper Bullet Handle 6"5 serr ",
"Description2":"Taper Bullet Ha"
}
],
"Table2":[
{
"chk":6,
"currentchk":1
}
]
}
In Here JSON Description column value contain "(double quotation) .If we check http://jsonformatter.curiousconcept.com/ , it show error.Its a Invalid JSON.
WCF service I have converted DataSet to JSON. Some table column contain special charters.
I converted like this :
public String ConverTableToJson(DataSet dsDownloadJson,int currentSplit)
{
StringBuilder Sb = new StringBuilder();
String result = "";
int start = 0;
int end =500;
int chk = 0;
int currentChk = currentSplit;
if (dsDownloadJson.Tables.Count > 0)
{
Sb.Append("{");
foreach (DataTable dt in dsDownloadJson.Tables)
{
DataTable dtDownloadJson = dt;
string[] StrDc = new string[dtDownloadJson.Columns.Count];
string HeadStr = string.Empty;
double total = dtDownloadJson.Rows.Count;
Console.WriteLine("--1--" + dtDownloadJson.Rows.Count);
if (dtDownloadJson.Rows.Count < 500)
{
end = dtDownloadJson.Rows.Count;
}
if (chk == 0)
{
if (dtDownloadJson.Rows.Count > 500)
{
if ((dtDownloadJson.Rows.Count / 500) == 0)
{
chk = dtDownloadJson.Rows.Count / 500;
}
else
{
chk = dtDownloadJson.Rows.Count / 500 + 1;
}
}
else
{
chk = 1;
}
currentChk = 1;
}
else
{
currentChk = currentChk + 1;
start = currentChk * 500;
end = start + 500;
currentChk = chk;
}
Sb.Append("\"" + dtDownloadJson.TableName + "1\" : [");
if (dtDownloadJson.Rows.Count > 0)
{
for (int i = 0; i < dtDownloadJson.Columns.Count; i++)
{
StrDc[i] = dtDownloadJson.Columns[i].Caption;
HeadStr += "\"" + StrDc[i] + "\" : \"" + StrDc[i] + i.ToString() + "¾" + "\",";
}
if (HeadStr.Length > 0)
{
HeadStr = HeadStr.Substring(0, HeadStr.Length - 1);
Console.WriteLine("--2--" + start);
Console.WriteLine("--3--" + end);
for (int i = start; i < end; i++)
{
string TempStr = HeadStr;
Sb.Append("{");
for (int j = 0; j < dtDownloadJson.Columns.Count; j++)
{
TempStr = TempStr.Replace(dtDownloadJson.Columns[j] + j.ToString() + "¾", dtDownloadJson.Rows[i][j].ToString());
TempStr = TempStr.Replace(""", '\"');
}
Sb.Append(TempStr + "},");
}
Sb = new StringBuilder(Sb.ToString().Substring(0, Sb.ToString().Length - 1));
}
}
else
{
}
Sb.Append("],");
if (chk > 1)
{
Sb.Append("\"Table2\": [{\"chk\": " + chk + ", \"currentchk\": " + currentChk + " }]");
}
else
{
Sb.Append("\"Table2\": [{\"chk\": " + chk + ", \"currentchk\": " + currentChk + " }]");
}
}
// Sb = new StringBuilder(Sb.ToString().Substring(0, Sb.ToString().Length - 1));
Sb.Append("}");
return Sb.ToString();
}
else
{
return "0";
}
}
My problem is removing special charters OR How to allow special characters.?
Please help me anybody...

You shouldn't use a StringBuilder to convert an object to a JSON string. Use the JsonConverter class in JayRock JSON library and it takes care of Serialising/Deserialising Json for you (including escaping)

try to use inbuilt json serialization
public static string Serialize<T>(T obj)
{
System.Runtime.Serialization.Json.DataContractJsonSerializer serializer = new
System.Runtime.Serialization.Json.DataContractJsonSerializer(obj.GetType());
MemoryStream ms = new MemoryStream();
serializer.WriteObject(ms, obj);
string retVal = Encoding.Default.GetString(ms.ToArray());
ms.Dispose();
return retVal;
}