Android Studio：某些手机上的应用程序崩溃

Question

我是 android 开发的新手，对这个问题感到非常困惑。 我正在制作一个简单的应用程序，它有 3 个 TextViews：text、text2 和 text3。

• 文本显示用户的纬度
• text2 显示用户的经度和
• text3 显示用户与名为“Azadi Square”的地方之间的距离。

应用程序在 Samsung Galaxy S4 和 Samsung Galaxy Tab S 上正常运行，但在 Huawei Y511 和 @987654324 之一@（我不知道确切的名称。），应用程序无法打开并显示 The App has unfortunately stopped

这是我的 Java 代码：

public class Map extends Activity implements LocationListener {

private TextView text,text2,text3;
private String provider;
private LocationManager locationManager;
private double latitude,longitude;
private Location azadiSquare;

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

    text = (TextView)findViewById(R.id.text);
    text2 = (TextView)findViewById(R.id.text2);
    text3 = (TextView)findViewById(R.id.text3);

    locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);

    Criteria criteria = new Criteria();
    provider = locationManager.getBestProvider(criteria,false);

    azadiSquare = new Location(provider);
    azadiSquare.setLatitude(35.6996540);
    azadiSquare.setLongitude(51.3379906);

    Location location = locationManager.getLastKnownLocation(provider);


    text.setText(location.getLatitude()+"");
    text2.setText(location.getLongitude()+"");
    text3.setText(distanceBetweenMeter(azadiSquare,location)+"");
}

@Override
protected void onResume() {
    super.onResume();

    locationManager.requestLocationUpdates(provider,400,1,this);
}

@Override
protected void onPause() {
    super.onPause();

    locationManager.removeUpdates(this);
}

@Override
public void onLocationChanged(Location location) {
    latitude = location.getLatitude();
    longitude = location.getLongitude();

    text.setText(latitude+"");
    text2.setText(longitude+"");

    text3.setText(distanceBetweenMeter(azadiSquare,location)+"");
}

@Override
public void onStatusChanged(String s, int i, Bundle bundle) {
    // TODO Auto-generated method stub
}

@Override
public void onProviderEnabled(String s) {
    Toast.makeText(this,"Enabled new provider " + provider,Toast.LENGTH_LONG).show();
}

@Override
public void onProviderDisabled(String s) {
    Toast.makeText(this,"Disabled provider " + provider,Toast.LENGTH_LONG).show();
}


private double getDistanceFromLatLonInKm(double lat1,double lon1,double lat2,double lon2) {
    double R = 6371; // Radius of the earth in km
    double dLat = deg2rad(lat2-lat1);  // deg2rad below
    double dLon = deg2rad(lon2-lon1);
    double a =
            Math.sin(dLat/2) * Math.sin(dLat/2) +
                    Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
                            Math.sin(dLon/2) * Math.sin(dLon/2)
            ;
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    double d = R * c; // Distance in km
    return d;
}

private double deg2rad(double deg) {
    return deg * (Math.PI/180);
}

private int distanceBetweenMeter(Location location1, Location location2){
    double distanceKM = getDistanceFromLatLonInKm(location1.getLatitude(),location1.getLongitude(),
            location2.getLatitude(),location2.getLongitude());
    int distanceMeter = (int)(distanceKM*1000);
    return distanceMeter;
}
}

注意：我刚刚删除了导入！

清单文件：

<?xml version="1.0" encoding="utf-8"?>

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".Map" android:screenOrientation="landscape">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

注意：我在打开应用之前打开了手机的位置，所以这不是问题。我想说的另一件事是，所有的计算都没有问题，并且运行良好。

Answer 1

在Android 6.0 (API level 23) 及更高版本上，您需要在运行时请求ACCESS_COARSE_LOCATION 和ACCESS_FINE_LOCATION 的权限。见，Requesting Permissions at Run Time。可能就是这样。

Answer 2

最好的办法是记录问题并回溯它，这样你就可以看到它哪里出了问题，或者至少有一个线索。如果 user35603 的回答无效，请尝试此操作并发布有关您的问题的 logcat 部分。

Answer 3

问题终于解决了！这部分代码出了问题：

Location location = locationManager.getLastKnownLocation(provider);

text.setText(location.getLatitude()+"");
text2.setText(location.getLongitude()+"");

我想location 需要一点时间才能获得当前位置。实际上，当 app 想要运行下面这行代码时， location 仍然为 null 并且 app 崩溃了：

text1.setText(location.getLatitude()+"");

我用这样的方法解决了崩溃：

Location location = locationManager.getLastKnownLocation(provider);

while(location==null){}

text.setText(location.getLatitude()+"");
text2.setText(location.getLongitude() + "");
text3.setText(distanceBetweenMeter(azadiSquare,location)+"");

崩溃已解决，但应用程序冻结并出现白屏。我不确切知道，但我猜它被困在 while 循环中。谢谢！

Answer 4

public class MainActivity extends AppCompatActivity {

pb=findViewById(R.id.progressbar);
Example ex=new Example();//The subclass object is created here
boolean stop=false;//a boolean variable to start or stop the thread to get location. 
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (location== null) {
        showSettingDialog();//this will show your custom way of displaying 
                              //the location setting intent
        new Thread(ex).start();//here the fetching location gets started
    }
    else{
       //here write code after your location is fetched
       //here to got some other base activity or stay in this
        finish();//if you wan to stay in this activity then omit this line.
    }
}

public class Example implements Runnable{ //This is a sub class in your main activity.

    @Override
    public void run() {//overriding run medthod
            try {

                while(location==null) { //this part keeps on running whithout 
                                         //ui freeze
                     if (stop) {
                        return;
                    }
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            pb.setVisibility(View.VISIBLE);
                        }
                    });

                    getLastLocation();//this function will fetch location.
                    Thread.sleep(1500);
                    pb.setVisibility(View.INVISIBLE);
                    if (location != null) {
                        //do your code here
                        stop = true;
                        finish();
                    }
                }
            }


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

            }

        }