我正在开发一个小应用程序，它获取当前的地理坐标并使用 json 对象返回相关地址。问题是：如果我在三星 Galaxy S 上运行应用程序，它可以完美运行，但是，如果我在 Galaxy S3 上运行它，则会发生运行时错误，例如，它获取当前位置坐标但无法检索 json 对象。代码如下：
package com.demobasar;
import android.content.Context;
import android.location.Criteria;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Handler;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
public class MainActivity extends ActionBarActivity implements LocationListener {
TextView longT, latT, ulke, sehir, ilce, sokak, mahalle;
private LocationManager locationManager;
private String provider;
Location location;
double lat, lng;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
longT = (TextView) findViewById(R.id.longT);
latT = (TextView) findViewById(R.id.lat);
ulke = (TextView) findViewById(R.id.ulke);
sehir = (TextView) findViewById(R.id.sehir);
ilce = (TextView) findViewById(R.id.ilce);
sokak = (TextView) findViewById(R.id.sokak);
mahalle =(TextView) findViewById(R.id.mahalle);
locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
location = locationManager.getLastKnownLocation(provider);
if (location != null) {
onLocationChanged(location);
} else {
longT.setText("Location not available");
latT.setText("Location not available");
}
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
try {
ulke.setText(getJson("http://maps.basarsoft.com.tr/yb5.ashx?f=rg&x=" + lng + "&y=" +lat).getString("Order0"));
sehir.setText(getJson("http://maps.basarsoft.com.tr/yb5.ashx?f=rg&x=" + lng + "&y=" +lat).getString("Order1"));
ilce.setText(getJson("http://maps.basarsoft.com.tr/yb5.ashx?f=rg&x=" + lng + "&y=" +lat).getString("Order8"));
mahalle.setText(getJson("http://maps.basarsoft.com.tr/yb5.ashx?f=rg&x=" + lng + "&y=" +lat).getString("Order9"));
sokak.setText(getJson("http://maps.basarsoft.com.tr/yb5.ashx?f=rg&x=" + lng + "&y=" +lat).getString("Street"));
} catch (JSONException e) {
e.printStackTrace();
}
}
}, 10000);
}
@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) {
lat = location.getLatitude();
lng = location.getLongitude();
longT.setText("" + lng);
latT.setText("" + lat);
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
Toast.makeText(this, "Enabled new provider " + provider,
Toast.LENGTH_SHORT).show();
}
@Override
public void onProviderDisabled(String provider) {
Toast.makeText(this, "Disabled provider " + provider,
Toast.LENGTH_SHORT).show();
}
public static JSONObject getJson(String url){
InputStream is = null;
String result = "";
JSONObject jsonObject = null;
try {
HttpClient httpclient = new DefaultHttpClient();
HttpGet httppost = new HttpGet(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch(Exception e) {
return null;
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"utf-8"),8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch(Exception e) {
return null;
}
try {
jsonObject = new JSONObject(result);
} catch(JSONException e) {
return null;
}
return jsonObject;
}
}
android清单如下：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.demobasar"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="10"
android:targetSdkVersion="19" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERACT_ACROSS_USERS_FULL"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.demobasar.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>
最后是LogCat：
01-19 22:01:14.689 23948-23948/com.demobasar E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.demobasar.MainActivity$1.run(MainActivity.java:68)
at android.os.Handler.handleCallback(Handler.java:730)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:176)
at android.app.ActivityThread.main(ActivityThread.java:5419)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
at dalvik.system.NativeStart.main(Native Method)