Develop Reference

Rounding to two decimal places in Android

Should be simple I know but I cant find an answer anywhere. I'm trying to round up to two decimal places, so if my answer is 164.9835 I'd like the answer to be displayed as 164.99. But what I have so far is rounding it to 164.98 for some reason.
Any help much appreciated.
double number1 = Double.parseDouble(num1.getText().toString());
double number2 = Double.parseDouble(num2.getText().toString());
double number3 = Double.parseDouble(num3.getText().toString());
double number4 = Double.parseDouble(num4.getText().toString());
double sum = (((number1 * number2)/1000)*0.5)*(number3 - number4);
total.setText (String.format("£%s", new java.text.DecimalFormat("##.##").format(sum)));

If you want to round up you can use this method
cantDecimal = 2;
number = 164.9835
public static double aroundUp(double number, int canDecimal) {
int cifras = (int) Math.pow(10, canDecimal);
return Math.ceil(number * cifras) / cifras;
}
return = 164.99
Extra: Ceil Method in Math.
The method ceil gives the smallest integer that is greater than or equal to the argument.

Why I can not see the double value in a textView

Why I can not see the double value in a textView?
textView = (TextView) findViewById(R.id.textView);
double x = 5/2;
textView.setText(String.valueOf(x)); // I see this result as 2.0 and not as the 2.5

In Android TextView, you can use in that way,
Use Double.toString:
result = number1/number2
String stringdouble= Double.toString(result);
textview1.setText(stringdouble));
or you can use the NumberFormat:
Double result = number1/number2;
NumberFormat nm = NumberFormat.getNumberInstance();
textview1.setText(nm.format(result));
To force for 3 units precision:
private static DecimalFormat REAL_FORMATTER = new DecimalFormat("0.###");
textview1.setText(REAL_FORMATTER.format(result));

You are seeing 2.0 because 5/2 is integer division. Change the line to double x = 5.0/2; or similar.
See this question for more.

This should work double x = ((double) 5) /2.

How to calculate distance between set of Latitudes and Longitudes in android?

I'm trying to calculate distance between LatLng points. It's easy to calculate for two coordinates. I have to calculate distance between more than two LatLngs and calculate the cumulative distance from a set of LatLngs. I calculated distance between two points as per the following code.
tvDistance=(TextView)findViewById(R.id.textView4);
Location loc1=new Location("");
loc1.setLatitude(11.2805);
loc1.setLongitude(77.5989);
Location loc2=new Location("");
loc2.setLatitude(11.2801);
loc2.setLongitude(77.5976);
DecimalFormat format=new DecimalFormat("#.##");
double distanceInMeters = loc1.distanceTo(loc2)/1000;
tvDistance.setText(format.format(distanceInMeters) + " Km's");
Now I have for example sixteen LatLng points. First is starting place and last is stopping place. I have the LatLngs in a ArrayList. tried the following code. But it caused ArrayIndexOutOfBoundException.
Do anybody know a method please share with me. Thanks.
private void calculateDistance() {
for (int i=0;i<coordList.size();i++){
LatLng l1=coordList.get(i);
double lat1=l1.latitude;
double lng1=l1.longitude;
Location location1=new Location("");
location1.setLatitude(lat1);
location1.setLongitude(lng1);
LatLng l2=coordList.get(i+1);
double lat2=l2.latitude;
double lng2=l2.longitude;
Location location2=new Location("");
location2.setLatitude(lat2);
location2.setLongitude(lng2);
DecimalFormat format=new DecimalFormat("#.##");
double distance=location1.distanceTo(location2)/1000;
Toast.makeText(MainPage.this,format.format(distance) + " Km's",Toast.LENGTH_SHORT).show();
}
}

You can use SphericalUtil.computeLength method:
http://googlemaps.github.io/android-maps-utils/javadoc/com/google/maps/android/SphericalUtil.html#computeLength-java.util.List-
Sources: https://github.com/googlemaps/android-maps-utils/blob/master/library/src/com/google/maps/android/SphericalUtil.java

The line
LatLng l2=coordList.get(i+1);
causes the exception.
jon

->Its easy to calculate the distance if you have sets of latitudes and longitudes
ArrayList<RideRoutes> ride_route_list = new ArrayList<>();
//suppose "ride_route_list" contains collections of Latitudes and longitudes
String distance_covered_str;
double total_meters = 0.0;
for(int i = 0; i < (ride_route_list.size() - 1); i++){
double previous_latitude = Double.parseDouble(ride_route_list.get(i).getRout_latitude());
double previous_longitude = Double.parseDouble(ride_route_list.get(i).getRout_longitude());
double updated_latitude = Double.parseDouble(ride_route_list.get(i+1).getRout_latitude());
double updated_longitude = Double.parseDouble(ride_route_list.get(i+1).getRout_longitude());
Location start_latlng = new Location("location_previous");
start_latlng.setLatitude(previous_latitude);
start_latlng.setLongitude(previous_longitude);
Location end_latlng = new Location("location_updated");
end_latlng.setLatitude(updated_latitude);
end_latlng.setLongitude(updated_longitude);
total_meters += start_latlng.distanceTo(end_latlng);
}
double distance_covered_km = total_meters / 1000;
distance_covered_str = String.format(Locale.getDefault(), "%.2f", distance_covered_km);
Note:
->here ride_route_list is an ArrayList which contains the list of Latitude and longitude
RideRoutes Class Structure:
public class RideRoutes {
private String rout_latitude;
private String rout_longitude;
public RideRoutes(String rout_latitude, String rout_longitude) {
this.rout_latitude = rout_latitude;
this.rout_longitude = rout_longitude;
}
public String getRout_latitude() {
return rout_latitude;
}
public void setRout_latitude(String rout_latitude) {
this.rout_latitude = rout_latitude;
}
public String getRout_longitude() {
return rout_longitude;
}
public void setRout_longitude(String rout_longitude) {
this.rout_longitude = rout_longitude;
}
}

how can i reduce the digits after the decimal point?

private void findLatLongDistance(double prelat,double prelon,double lat,double lon) {
// TODO Auto-generated method stub
try{
double prelatval=prelat;
double prelongval=prelon;
double curlat=lat;
double curlon=lon;
Log.w("inside finalatlon...........................","the daya");
if(prelatval>0.0 && prelongval>0.0 && lat>0.0 && lat>0.0 && gpsdataElements.Speed>0.0){
float distance2 = getDistance(prelatval,prelongval,curlat,curlon);
odometer_sum= (distance2/1000 );
// for maximum value after decimal
//df.setMaximumFractionDigits(0);
//rounding the km digits after decimal
Math.round(distance2);
//for minimum distance after decimal
df.setMinimumFractionDigits(2);
df.format(odometer_sum);
gpsdataElements.Distance = gpsdataElements.Distance + odometer_sum;
}
}catch(Exception e){
e.printStackTrace();
}
}
here is my code. I want distance(i.e km)value digits after decimal is two digits. Example i want km value in 1.54km not like 1.4568923km. How to get like this.I tried a lot for that but i din't got any possible solution. Any one know please help me.

In more simple ways you can do this by using this :
double roundOff = Math.round(yourValue * 100.0) / 100.0;
Otherwise you can also do this as
String.format("%.2f", d)

DecimalFormat formatter = new DecimalFormat(".##");
String s = formatter.format(value);

use this code to format text in two digits after decimal.
double i2=i/60000;
tv.setText(new DecimalFormat("##.##").format(i2));

double roundof = Math.round(a * 100.0) / 100.0;
output:roundoff(eg:12).oo
12.00

Something like this :
String.format("%.2f", distance);

Make function like this pass the value as per you requirment and return value as per your requirment first function will take float value and after decimal it put 3 value as per argument if you want to change decimal value then you can change 3,2,4 etc... Second function will take String value and round it in 3 decimal point:
public static BigDecimal round(float d) {
BigDecimal bd = new BigDecimal(Float.toString(d));
bd = bd.setScale(3, BigDecimal.ROUND_HALF_UP);
return bd;
}
public static BigDecimal round(String d) {
BigDecimal bd = new BigDecimal(Float.parseFloat(d));
bd = bd.setScale(3, BigDecimal.ROUND_HALF_UP);
return bd;
}

Display decimals with a textview

Hi i want make so the TextView level can put out decimal but i don'ty know how to do that any one got an idea? NOw it only puts out 1 but i want it to put out 1.80. :)
public class Main extends Activity {
int counter;
EditText weight, hours;
TextView amount, level;
Button calcuate;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
counter = 0;
weight = (EditText) findViewById(R.id.weight);
hours = (EditText) findViewById(R.id.hours);
amount = (TextView) findViewById(R.id.amount);
level = (TextView) findViewById(R.id.alcohol_level);
calcuate = (Button) findViewById(R.id.calcuate);
final String widmark = getResources().getString(
R.string.widmark);
final String hundra = getResources().getString(
R.string.hundra);
final String cl = getResources().getString(
R.string.cl);
calcuate.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Integer wid, mgs;
String w = weight.getText().toString();
String h = hours.getText().toString();
wid = Integer.parseInt(w) * Integer.parseInt(widmark) / Integer.parseInt(hundra);
mgs = Integer.parseInt(cl) / Integer.parseInt(wid.toString()) / Integer.parseInt(hundra);
level.setText(mgs.toString());
}
});
}
}

Your mgs variable is a Integer object. Set it to type float to have decimal places be displayed.
float mgs = Integer.parseInt(cl) / Integer.parseInt(wid.toString()) / Integer.parseInt(hundra);
I hope this helps.

int division will only produce int's. If you want your output to be of float or double type, you must use double or float division.
Double mgs;
mgs = Double.parseDouble(cl) / Double.parseDouble(wid.toString()) / Double.parseDouble(hundra);
Note that not all variables considered in the expression need to be double's, only one of them does.
Another thing that is noteworthy here is whether or not you want two decimal places (assuming a currency here). By default, Java/Android will only spit out as many decimal places as necessary. 1.80 will display as 1.8. To alleviate this, you should use a NumberFormat (specifically, use NumberFormat.getCurrencyInstance()) so that you can specify that you want the number of decimals for your default Locale's currency.