我将纬度和经度作为用户输入并计算两点之间的距离。我收到以下错误。
这是代码：
package com.example.garima.cal;
import android.location.Location;
import android.nfc.Tag;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.app.Dialog;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.inputmethod.EditorInfo;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.TextView.OnEditorActionListener;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.vision.barcode.Barcode;
public class MainActivity extends FragmentActivity {
private GoogleMap mMap;
private GoogleMap googleMap;
EditText etLng;
EditText etLat;
EditText etLng2;
EditText etLat2;
private static LatLng point,point2;
private String TAG ="Main Activity";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
// Reference to the EditText et_lat of the layout activity_main.xml
etLat = (EditText) findViewById(R.id.et_lat);
// Reference to the EditText et_lng of the layout activity_main.xml
etLng = (EditText) findViewById(R.id.et_lng);
etLat2 = (EditText) findViewById(R.id.et_lat2);
etLng2 = (EditText) findViewById(R.id.et_lng2);
etLng.setOnEditorActionListener(new OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
if (actionId == EditorInfo.IME_ACTION_DONE) {
// Getting the entered latitude
String lat = etLat.getText().toString();
// Getting the entered longitude
String lng = etLng.getText().toString();
// Getting the entered latitude
// LatLng object to store user input coordinates
point = new LatLng(Double.parseDouble(lat), Double.parseDouble(lng));
}
return false;
}
});
etLng2.setOnEditorActionListener(new OnEditorActionListener() {
@Override
public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
if (actionId == EditorInfo.IME_ACTION_DONE) {
// Getting the entered latitude
String lat2 = etLat2.getText().toString();
// Getting the entered longitude
String lng2 = etLng2.getText().toString();
// Getting the entered latitude
// LatLng object to store user input coordinates
point2=new LatLng(Double.parseDouble(lat2), Double.parseDouble(lng2));
calculateDist(point,point2);
}
return false;
}
});
//calculate distance
//Log.i(TAG,"The calculated distance is "+distance);
}
private void calculateDist(LatLng point,LatLng point2){
float [] dist = new float[1];
Location.distanceBetween(point.longitude,point.latitude,point2.longitude,point2.latitude,dist);
String distances = String.valueOf(dist[0]);
TextView distanceView = (TextView) findViewById(R.id.txt_distance);
System.out.println(distances);
distanceView.setText(distances+" m");
}
}
这是错误：
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.garima.taxfix_cal, PID: 2952
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.garima.taxfix_cal/com.example.garima.taxfix_cal.MainActivity}: java.lang.NullPointerException: Attempt to read from field 'double com.google.android.gms.maps.model.LatLng.longitude' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to read from field 'double com.google.android.gms.maps.model.LatLng.longitude' on a null object reference
at com.example.garima.taxfix_cal.MainActivity.calculateDist(MainActivity.java:118)
at com.example.garima.taxfix_cal.MainActivity.onCreate(MainActivity.java:111)
at android.app.Activity.performCreate(Activity.java:5937)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread