java - 致命异常 : main with android and eclipse

Question

我正在 Android 中制作一个简单的基于 GPS/Google map 的应用程序，当我即将完成它时，它抛出了这个可怕的错误。我真的不知道从哪里开始尝试调试它，因为它不会在我在主要 Activity 中放置的任何断点处停止，而且我对 android、java 或 eclipse 不太熟悉。因此，虽然很烦人，但我只是将整个主文件转储到这里

基本上，该应用程序的重点是它会找出您所在的位置，然后您可以选择根据您所在的位置显示维基百科文章

编辑:我尝试重新启动模拟器、Eclipse、清理和重建

任何帮助将不胜感激

日志猫:

05-21 03:41:45.283: E/AndroidRuntime(1846): FATAL EXCEPTION: main
05-21 03:41:45.283: E/AndroidRuntime(1846): Process: com.example.playservicestest, PID: 1846
05-21 03:41:45.283: E/AndroidRuntime(1846): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.playservicestest/com.example.playservicestest.MainActivity}: java.lang.NullPointerException
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.os.Handler.dispatchMessage(Handler.java:102)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.os.Looper.loop(Looper.java:136)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.ActivityThread.main(ActivityThread.java:5017)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at java.lang.reflect.Method.invokeNative(Native Method)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at java.lang.reflect.Method.invoke(Method.java:515)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at dalvik.system.NativeStart.main(Native Method)
05-21 03:41:45.283: E/AndroidRuntime(1846): Caused by: java.lang.NullPointerException
05-21 03:41:45.283: E/AndroidRuntime(1846):     at com.example.playservicestest.MainActivity.onCreate(MainActivity.java:101)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.Activity.performCreate(Activity.java:5231)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
05-21 03:41:45.283: E/AndroidRuntime(1846):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
05-21 03:41:45.283: E/AndroidRuntime(1846):     ... 11 more

来源:

package com.example.playservicestest;

import java.io.IOException;
import java.util.List;
import java.util.Locale;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.location.Address;
import android.location.Criteria;
import android.location.Geocoder;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {

    //Map globals
    LocationManager mLocationManager ;
    Criteria mCriteria = new Criteria();
    String mBestProvider;
    Location mLocation;

    GoogleMap mMap;
    GeoPoint mMapPosition;

    //String globals
    String localityString;
    String countryString;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Widget assigning
        TextView tLocationText = (TextView) findViewById(R.id.Location_text);


        //Location Initialising
        mLocationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
        mBestProvider = mLocationManager.getBestProvider(mCriteria, false);
        mLocation = mLocationManager.getLastKnownLocation(mBestProvider);

        mCriteria.setAccuracy(Criteria.ACCURACY_COARSE);
        mCriteria.setPowerRequirement(Criteria.POWER_LOW);
        mCriteria.setAltitudeRequired(false);
        mCriteria.setBearingRequired(false);
        mCriteria.setSpeedRequired(false);
        mCriteria.setCostAllowed(true);

        localityString = "Nothing yet!";
        countryString = "Nothing yet!";


        int iminTime = 2000;
        int iminDistance = 50;
        LocationListener mLocationListener = new LocationListener() 
        {
            public void onLocationChanged(Location location) 
            {
                // Update application based on new location.
                updateLocation(location);
            }
            public void onProviderDisabled(String provider)
            {
                // Update application if provider disabled.
                updateLocation(null);
            }
            public void onProviderEnabled(String provider)
            {
                // Update application if provider enabled.
            }
            public void onStatusChanged(String provider, int status,Bundle extras)
            {
                // Update application if provider hardware status changed.
            }
        };

        updateLocation(mLocation);
        mLocationManager.requestLocationUpdates(mBestProvider, iminTime, iminDistance, mLocationListener);

        mMap = ((MapFragment) getFragmentManager().findFragmentById(R.id.map_fragment)).getMap();

        LatLng CurrPos = new LatLng(mLocation.getLatitude(),mLocation.getLongitude());
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(CurrPos, 13));

        Button bCurrentPosition = (Button)findViewById(R.id.Current_pos);
        bCurrentPosition.setOnClickListener(CurrentPositionListener);

        Button bChangePosition = (Button)findViewById(R.id.Change_pos);
        bChangePosition.setOnClickListener(ChangePositionListener);
    }


    public void callIntent(View view)
    {
        Intent intent = null;
        if(view.getId()==R.id.Find_info)
        {
            if(localityString!="Somewhere in")
            {
                intent = new Intent(Intent.ACTION_VIEW,Uri.parse("http://en.wikipedia.org/wiki/"+localityString));
            }
            else if(countryString!="the middle of the ocean")
            {
                intent = new Intent(Intent.ACTION_VIEW,Uri.parse("http://en.wikipedia.org/wiki/"+countryString));
            }
            else
            {
                intent = new Intent(Intent.ACTION_VIEW,Uri.parse("http://en.wikipedia.org/wiki/Ocean"));
            }
        }
        startActivity(intent);
    }

    View.OnClickListener CurrentPositionListener = new View.OnClickListener() 
    {
        @Override
        public void onClick(View v) 
        {
            findCurrentPosition();
        }
    };

    View.OnClickListener ChangePositionListener = new View.OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            setTargetPosition();
        }
    };

    public void updateLocation(Location location)
    {
        TextView mtextview = (TextView)findViewById(R.id.Location_text);

        if(location !=null)
        {
            mtextview.setText("Lat: "+location.getLatitude()+"\nLong: "+location.getLongitude()+"\n");
        }
        else
        {
            mtextview.setText("No Location found");
        }
    }

    public void findCurrentPosition()
    {
        if(mLocation !=null)
        {
            LatLng CurrPos = new LatLng(mLocation.getLatitude(),mLocation.getLongitude());
            mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(CurrPos, 5.0f));

            double lat = mLocation.getLatitude();
            double lng = mLocation.getLongitude();

            LatLng Point = new LatLng(lat,lng);
            setAddressMarker(Point);    
        }
    }

    public void setTargetPosition()
    {
        TextView tLocationText = (TextView) findViewById(R.id.Location_text);

        CameraPosition TargetPosition = mMap.getCameraPosition();

        double lat = TargetPosition.target.latitude;
        double lng = TargetPosition.target.longitude;

        LatLng Point = new LatLng(lat,lng);

        setAddressMarker(Point);    
    }

    void setAddressMarker(LatLng Point)
    {
        TextView tLocationText = (TextView) findViewById(R.id.Location_text);

        Geocoder gc = new Geocoder(this);


        try{
            List<Address> addresses = gc.getFromLocation(Point.latitude, Point.longitude, 1);
            //targetAddress.getLocale()

            if(addresses.size()>0)
            {
                Address targetAddress = addresses.get(0);   

                if(targetAddress.getLocality()!=null)
                {
                    localityString = targetAddress.getLocality();
                }
                else
                {
                    localityString = "Somewhere in";
                }

                if(targetAddress.getCountryName()!=null)
                {
                    countryString = targetAddress.getCountryName();
                }
                else
                {
                    countryString = "the middle of the ocean";
                }

            }
            else
            {
                localityString = "Somewhere in";
                countryString = "the middle of the ocean";
            }

        }
        catch (IOException e) 
        {
            e.printStackTrace();
        }

        tLocationText.setText("You're target is: "+ localityString +" "+ countryString);

        mMap.addMarker(new MarkerOptions()
        .title(localityString)
        .snippet(countryString)
        .position(Point));
    }
}

list 文件:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.playservicestest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="18" />

    <uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
<!-- The following two permissions are not required to use
     Google Maps Android API v2, but are recommended. -->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

<uses-feature
        android:glEsVersion="0x00020000"
        android:required="true"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <meta-data android:name="com.google.android.gms.version"
           android:value="@integer/google_play_services_version" />
        <meta-data
    android:name="com.google.android.maps.v2.API_KEY"
    android:value="AIzaSyA4XfZDxD_pzC4wyF4nsQPjvMZIl3V-Mew"/>
        <activity
            android:name="com.example.playservicestest.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Answer 1

所以问题是位置，请从互联网上查看一些如何使用它的示例。像这样https://thenewcircle.com/s/post/311/tutorial_android_location_service_example