My following simple code shows no errors, yet does not execute. FATAL EXCEPTION: main java.lang.RunTimeException: Unable to start activity.... java.lang.NullPointerException.
package com.example.mapstestmednex;
import android.app.Activity;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.view.Menu;
import android.widget.TextView;
public class MainActivity extends Activity {
private LocationManager lm;
private LocationListener localListenD;
public TextView tvLatitude;
public TextView tvLongitude;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lm = (LocationManager) getSystemService(LOCATION_SERVICE);
Location loc = lm.getLastKnownLocation("gps");
tvLatitude.setText(Double.toString(loc.getLatitude()));
tvLongitude.setText(Double.toString(loc.getLatitude()));
localListenD = new DipsListLocListener();
lm.requestLocationUpdates("gps", 30000L, 10.0f, localListenD);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
class DipsListLocListener implements LocationListener {
@Override
public void onLocationChanged(Location location) {
tvLatitude.setText(Double.toString(location.getLatitude()));
tvLongitude.setText(Double.toString(location.getLatitude()));
}
@Override
public void onProviderDisabled(String arg0) {
}
@Override
public void onProviderEnabled(String arg0) {
}
@Override
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
}
}
}
xml-file
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<TextView
android:id="@+id/lblLatitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Latitude:" />
<TextView
android:id="@+id/tvLatitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/lblLongitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Longitude:" />
<TextView
android:id="@+id/tvLongitude"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
What's the problem? Thanks.
You never initialize the public TextView tvLatitude; public TextView tvLongitude;
You should do tvLatitude = new TextView(); first, so you can can setText on it later.
The same for tvLongtitude. Hope that helps
You need
tvLatitude = (TextView) findViewById(R.id.tvLatitude);
before you access tvLatitude
, such as to set its text. Likewise tvLongitude
.
Check your activity_main layout
. You probably have textviews to show latitude and longitude. So after setContentView(R.layout.activity_main), add these two..
tvLatitude = (TextView) findViewById(R.id.lblLatitude);
tvLongitude = (TextView) findViewById(R.id.lblLongitude);
Make sure you replace R.id.lblLatitude
and R.id.lblLongitude
with the right ids in your layout.
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