应用程序崩溃时，有没有持续的互联网连接

本文介绍了应用程序崩溃时，有没有持续的互联网连接的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

以下code是从谷歌地图的活动找到用户input.It工作正常，但崩溃的特定位置时，有没有持续的互联网connection.Please帮我解决这个问题。    该MainActivity.java类看起来是这样的：

进口android.location.Address;进口android.location.Geo codeR;进口android.os.AsyncTask;进口android.os.Bundle;进口android.support.v4.app.FragmentActivity;进口android.view.View;进口android.view.View.OnClickListener;进口android.widget.Button;进口android.widget.EditText;进口android.widget.Toast;进口com.google.android.gms.maps.CameraUpdateFactory;进口com.google.android.gms.maps.GoogleMap;进口com.google.android.gms.maps.SupportMapFragment;进口com.google.android.gms.maps.model.LatLng;进口com.google.android.gms.maps.model.MarkerOptions;进口java.io.IOException异常;进口的java.util.List;公共类MainActivity    扩展FragmentActivity {    GoogleMap的GoogleMap的;    的MarkerOptions的MarkerOptions;    经纬度的latLng;    @覆盖    保护无效的onCreate（捆绑savedInstanceState）{        super.onCreate（savedInstanceState）;        的setContentView（R.layout.activity_main）;        SupportMapFragment supportMapFragment =（SupportMapFragment）getSupportFragmentManager（）findFragmentById（R.id.map）。        //获取到地图的参考        GoogleMap的= supportMapFragment.getMap（）;        //获取参考btn_find布局activity_main的        按钮btn_find =（按钮）findViewById（R.id.btn_find）;        //定义按钮点击事件侦听器查找按钮        OnClickListener findClickListener =新OnClickListener（）{            @覆盖            公共无效的onClick（视图v）{                的EditText etLocation =（EditText上）findViewById（R.id.et_location）;                //获取用户输入的位置                。字符串位置= etLocation.getText（）的toString（）;                如果（位置= NULL＆放大器;！＆安培;！location.equals（））{                    新的地缘coderTask（）执行（位置）;                }            }        };        //设置按钮点击事件侦听器查找按钮        btn_find.setOnClickListener（findClickListener）;    }    //一个AsyncTask的类访问地址解析网络服务    私有类地理coderTask        延伸AsyncTask的＆LT;弦乐，太虚，列表与LT;地址＆gt;＆GT; {        @覆盖        保护列表与LT;地址＆gt; doInBackground（字符串... LOCATIONNAME）{            //创建地理codeR类的一个实例            地理codeR地理codeR =新的地缘codeR（getBaseContext（））;            清单＆LT;地址＆gt;地址= NULL;            尝试{                //获取最多3个地址，输入文本相匹配                地址=地理coder.getFromLocationName（LOCATIONNAME [0]，3）;            }赶上（IOException异常五）{                e.printStackTrace（）;            }            返回地址;        }        @覆盖        保护无效onPostExecute（列表＆LT;地址＆gt;地址）{            如果（地址== NULL || addresses.size（）== 0）{                Toast.makeText（getBaseContext（），无位置找到Toast.LENGTH_SHORT）.show（）;            }            //清除地图上所有的现有标记            googleMap.clear（）;            //添加谷歌地图上标记为每个匹配的地址            的for（int i = 0; I＆LT; addresses.size（）;我++）{                地址地址=（地址）addresses.get（I）                //创建的GeoPoint的一个实例，在谷歌地图中显示                的latLng =新经纬度（address.getLatitude（），address.getLongitude（））;                串addressText =的String.format（％S％S，address.getMaxAddressLineIndex（）大于0 address.getAddressLine（0）：，address.getCountryName（））;                的MarkerOptions =新的MarkerOptions（）;                markerOptions.position（的latLng）;                markerOptions.title（addressText）;                googleMap.addMarker（的MarkerOptions）;                //找到的第一个位置                如果（我== 0）{                    googleMap.animateCamera（CameraUpdateFactory.newLatLng（的latLng））;                }            }        }    }}

这是我的崩溃报告：

02-25 17：17：42.157 4312-4312 / aravindaby.myapp123 E /测试：异常02-25 17：17：42.157 4312-4312 / aravindaby.myapp123 E / AndroidRuntime：致命异常：主要显示java.lang.NullPointerException在aravindaby.myapp123.MainActivity $地理coderTask.onPostExecute（MainActivity.java:100）在aravindaby.myapp123.MainActivity $地理coderTask.onPostExecute（MainActivity.java:72）在android.os.AsyncTask.finish（AsyncTask.java:631）在android.os.AsyncTask.access $ 600（AsyncTask.java:177）在android.os.AsyncTask $ InternalHandler.handleMessage（AsyncTask.java:644）在android.os.Handler.dispatchMessage（Handler.java:99）在android.os.Looper.loop（Looper.java:137）在android.app.ActivityThread.main（ActivityThread.java:4793）在java.lang.reflect.Method.invokeNative（本机方法）在java.lang.reflect.Method.invoke（Method.java:511）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:808）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:575）在dalvik.system.NativeStart.main（本机方法）

解决方案

在没有互联网连接的情况下，地址是空。所以显示吐司消息后，你应该收益控制。

如果（地址== NULL || addresses.size（）== 0）{        Toast.makeText（getBaseContext（），无位置找到Toast.LENGTH_SHORT）.show（）;        返回;}

The following code is from a Google maps activity to find a particular location on user input.It works fine but crashes when there is no persistent internet connection.Please help me fix this problem. The MainActivity.java class looks like this:

import android.location.Address; import android.location.Geocoder; import android.os.AsyncTask; import android.os.Bundle; import android.support.v4.app.FragmentActivity; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import com.google.android.gms.maps.CameraUpdateFactory; import com.google.android.gms.maps.GoogleMap; import com.google.android.gms.maps.SupportMapFragment; import com.google.android.gms.maps.model.LatLng; import com.google.android.gms.maps.model.MarkerOptions; import java.io.IOException; import java.util.List; public class MainActivity extends FragmentActivity { GoogleMap googleMap; MarkerOptions markerOptions; LatLng latLng; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); SupportMapFragment supportMapFragment = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map); // Getting a reference to the map googleMap = supportMapFragment.getMap(); // Getting reference to btn_find of the layout activity_main Button btn_find = (Button) findViewById(R.id.btn_find); // Defining button click event listener for the find button OnClickListener findClickListener = new OnClickListener() { @Override public void onClick(View v) { EditText etLocation = (EditText) findViewById(R.id.et_location); // Getting user input location String location = etLocation.getText().toString(); if (location != null && !location.equals("")) { new GeocoderTask().execute(location); } } }; // Setting button click event listener for the find button btn_find.setOnClickListener(findClickListener); } // An AsyncTask class for accessing the GeoCoding Web Service private class GeocoderTask extends AsyncTask<String, Void, List<Address>> { @Override protected List<Address> doInBackground(String... locationName) { // Creating an instance of Geocoder class Geocoder geocoder = new Geocoder(getBaseContext()); List<Address> addresses = null; try { // Getting a maximum of 3 Address that matches the input text addresses = geocoder.getFromLocationName(locationName[0], 3); } catch (IOException e) { e.printStackTrace(); } return addresses; } @Override protected void onPostExecute(List<Address> addresses) { if (addresses == null || addresses.size() == 0) { Toast.makeText(getBaseContext(), "No Location found", Toast.LENGTH_SHORT).show(); } // Clears all the existing markers on the map googleMap.clear(); // Adding Markers on Google Map for each matching address for (int i = 0; i < addresses.size(); i++) { Address address = (Address) addresses.get(i); // Creating an instance of GeoPoint, to display in Google Map latLng = new LatLng(address.getLatitude(), address.getLongitude()); String addressText = String.format("%s, %s", address.getMaxAddressLineIndex() > 0 ? address.getAddressLine(0) : "", address.getCountryName()); markerOptions = new MarkerOptions(); markerOptions.position(latLng); markerOptions.title(addressText); googleMap.addMarker(markerOptions); // Locate the first location if (i == 0) { googleMap.animateCamera(CameraUpdateFactory.newLatLng(latLng)); } } } } }

And this is my crash report:

02-25 17:17:42.157 4312-4312/aravindaby.myapp123 E/test: Exception 02-25 17:17:42.157 4312-4312/aravindaby.myapp123 E/AndroidRuntime: FATAL EXCEPTION: main java.lang.NullPointerException at aravindaby.myapp123.MainActivity$GeocoderTask.onPostExecute(MainActivity.java:100) at aravindaby.myapp123.MainActivity$GeocoderTask.onPostExecute(MainActivity.java:72) at android.os.AsyncTask.finish(AsyncTask.java:631) at android.os.AsyncTask.access$600(AsyncTask.java:177) at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4793) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:808) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:575) at dalvik.system.NativeStart.main(Native Method)

解决方案

In the case of no internet connection, address is null. So after showing Toast message, you should return the control.

if(addresses==null || addresses.size()==0){ Toast.makeText(getBaseContext(), "No Location found", Toast.LENGTH_SHORT).show(); return; }