This is a simple Android app that uses two activities. This app uses Google Maps API.
- Download Android studio and install
- Create a new blank activity - this is the launcher activity
- Login to google and enable Maps API by providing SHA-1 value of your client
- C:\Users\xyz>keytool -list -v -keystore "%USERPROFILE%\.android\debug.keystore" -alias androiddebugkey -storepass android -keypass android
- Register ssh-1 key in google API console along with application package name
- Get the key and save it in android manifest
- Launcher activity creates a new private class that extends AsyncTask
- This class is responsible to call the API to retrieve JSON rest call
- JSON output is parsed and we only retrieve few values we needed from the json hierarchy
- There is a second button that invokes a MapsActivity when clicked by passing latitude and longitude via intent
- This app uses free http://api.openweathermap.org weather API
Important file contents
<resources>
<string name="google_maps_key_instructions" templateMergeStrategy="replace">
<string name="google_maps_key" templateMergeStrategy="preserve">GoogleAPIKeyHere</string>
</resources>
package com.example.xyz.myapplication;
import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;
public class MainActivity3 extends ActionBarActivity implements View.OnClickListener {
public static final String RESTAPI_URL = "http://api.openweathermap.org/data/2.5/weather?q=";
public static final String UNITS = "&units=metric";
EditText result;
EditText cityCountry;
ProgressBar pb;
Button button;
String longitude;
String latitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_activity3);
pb = (ProgressBar) findViewById(R.id.progressBar2);
pb.setVisibility(View.GONE);
button = (Button) findViewById(R.id.show);
button.setOnClickListener(this);
Button mapButton = (Button) findViewById(R.id.showMap);
mapButton.setOnClickListener(this);
}
@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_activity3, 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);
}
@Override
public void onClick(View v) {
if( v.getId() == R.id.showMap ) {
Intent intent = new Intent(this, MapsActivity.class);
intent.putExtra("lat", Double.parseDouble(latitude));
intent.putExtra("long", Double.parseDouble(longitude));
startActivity(intent);
}
//else
result = (EditText)findViewById(R.id.result);
cityCountry = (EditText)findViewById(R.id.cityCountry);
pb = (ProgressBar) findViewById(R.id.progressBar2);
pb.setVisibility(View.VISIBLE);
//call web service
AsyncTaskService service = new AsyncTaskService();
service.execute(cityCountry.getText().toString());
}
private class AsyncTaskService extends AsyncTask<String, Integer, String> {
String jSonContent;
String resultToDisplay;
@Override
protected String doInBackground(String... params) {
postData(params[0]);
return null;
}
protected void onPostExecute(String serviceResult){
pb.setVisibility(View.GONE);
result.setText(resultToDisplay);
}
protected void onProgressUpdate(Integer... progress){
pb.setProgress(progress[0]);
}
public void postData(String valueIWantToSend) {
// HTTP Get
BufferedReader reader = null;
try {
URL url = new URL(RESTAPI_URL+valueIWantToSend+UNITS);
StringBuilder sb = new StringBuilder();
String line = null;
reader = new BufferedReader(new InputStreamReader(url.openConnection().getInputStream()));
// Read Server Response
while((line = reader.readLine()) != null)
{
// Append server response in string
sb.append(line + "");
System.out.println("Response:"+ line);
}
// Append Server Response To Content String
jSonContent = sb.toString();
parseJson(jSonContent);
} catch (Exception e ) {
System.out.println(e.getMessage());
}
}
private void parseJson(String rawJson) {
JSONObject jsonResponse;
StringBuffer sb = new StringBuffer();
try {
jsonResponse = new JSONObject(rawJson);
JSONObject coord = jsonResponse.getJSONObject("coord");
longitude = coord.getString("lon");
latitude = coord.getString("lat");
sb.append("Latitude:" + latitude);
sb.append("\nLongitude:" + longitude);
JSONObject sys = jsonResponse.getJSONObject("sys");
String countryCode = sys.getString("country");
sb.append("\nCountry Code:" + countryCode);
JSONObject main = jsonResponse.getJSONObject("main");
String minTemp = main.getString("temp_min");
String maxTemp = main.getString("temp_max");
sb.append("\nMin Temp:" + minTemp);
sb.append("\nMax Temp:" + maxTemp);
String cityName = jsonResponse.getString("name");
sb.append("\nCity Name:" + cityName);
resultToDisplay = sb.toString();
} catch (Exception e ) {
}
}
}
}
public class MapsActivity extends FragmentActivity {
private GoogleMap mMap; // Might be null if Google Play services APK is not available.
double latitude;
double longitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
Intent intent = getIntent();
latitude = intent.getDoubleExtra("lat", 0);
longitude = intent.getDoubleExtra("long", 0);
System.out.println("******Latitude"+latitude);
System.out.println("******Longitude:"+longitude);
setUpMapIfNeeded();
mMap.setMyLocationEnabled(true);
}
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
}
/**
* Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
* installed) and the map has not already been instantiated.. This will ensure that we only ever
* call {@link #setUpMap()} once when {@link #mMap} is not null.
* <p/>
* If it isn't installed {@link SupportMapFragment} (and
* {@link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
* install/update the Google Play services APK on their device.
* <p/>
* A user can return to this FragmentActivity after following the prompt and correctly
* installing/updating/enabling the Google Play services. Since the FragmentActivity may not
* have been completely destroyed during this process (it is likely that it would only be
* stopped or paused), {@link #onCreate(Bundle)} may not be called again so we should call this
* method in {@link #onResume()} to guarantee that it will be called.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null) {
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
// Check if we were successful in obtaining the map.
if (mMap != null) {
setUpMap();
}
}
}
/**
* This is where we can add markers or lines, add listeners or move the camera. In this case, we
* just add a marker near Africa.
* <p/>
* This should only be called once and when we are sure that {@link #mMap} is not null.
*/
private void setUpMap() {
//mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
LatLng position = new LatLng(latitude, longitude);
// create marker
MarkerOptions marker = new MarkerOptions().position(position).title("Hello Maps ");
// adding marker
mMap.addMarker(marker);
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(position, 4));
}
}
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