我知道这个问题已经有很多例子，但我似乎无法找到一个特定于我的情况的答案。我一直在关注我在网上看过的一个教程，很多反馈说它对他们有用。运行模拟器时显示带有背景的屏幕，但随后崩溃并显示错误消息“不幸的是，Sabre1已停止”。 这是我的.java文件代码
public class MainActivity extends Activity {
private String jsonResult;
private String url = "localhost/foldername/connection php"; //-my connection string in .php
private ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listView1);
accessWebService();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
// Async Task to access the web
private class JsonReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(
response.getEntity().getContent()).toString();
}
catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
}
catch (IOException e) {
// e.printStackTrace();
Toast.makeText(getApplicationContext(),
"Error..." + e.toString(), Toast.LENGTH_LONG).show();
}
return answer;
}
@Override
protected void onPostExecute(String result) {
ListDrwaer();
}
}// end async task
public void accessWebService() {
JsonReadTask task = new JsonReadTask();
// passes values for the urls string array
task.execute(new String[] { url });
}
// build hash set for list view
public void ListDrwaer() {
List<Map<String, String>> employeeList = new ArrayList<Map<String, String>>();
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("login_tb");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
String Fname = jsonChildNode.optString("Fname");
String Mname = jsonChildNode.optString("Mname");
String Lname = jsonChildNode.optString("Lname");
String number = jsonChildNode.optString("Employee_ID");
String outPut = Fname + "-" + Mname + "-" + Lname + "-" + number;
employeeList.add(createEmployee("employees", outPut));
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
SimpleAdapter simpleAdapter = new SimpleAdapter(this, employeeList,
android.R.layout.simple_list_item_1,
new String[] { "employees" }, new int[] { android.R.id.text1 });
listView.setAdapter(simpleAdapter);
}
private HashMap<String, String> createEmployee(String name, String number) {
HashMap<String, String> employeeNameNo = new HashMap<String, String>();
employeeNameNo.put(name, number);
return employeeNameNo;
}
}
这是我的.xml文件代码
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity"
android:background="@drawable/adservewelcome">
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="14dp" >
</ListView>
</RelativeLayout>
这是我的logcat错误
12-20 04:08:04.360: E/memtrack(2466): Couldn't load memtrack module (No such file or directory)
12-20 04:08:04.360: E/android.os.Debug(2466): failed to load memtrack module: -2
12-20 04:13:13.410: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:13.420: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:13.430: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:13.430: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:13.430: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:13.430: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressStandard.ogg
12-20 04:13:13.430: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressSpacebar.ogg
12-20 04:13:13.500: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressDelete.ogg
12-20 04:13:13.500: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressReturn.ogg
12-20 04:13:13.600: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressInvalid.ogg
12-20 04:13:21.960: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:22.020: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:22.140: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:22.160: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:22.170: E/SoundPool(1820): error loading /system/media/audio/ui/Effect_Tick.ogg
12-20 04:13:22.240: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressStandard.ogg
12-20 04:13:22.240: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressSpacebar.ogg
12-20 04:13:22.250: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressDelete.ogg
12-20 04:13:22.270: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressReturn.ogg
12-20 04:13:22.280: E/SoundPool(1820): error loading /system/media/audio/ui/KeypressInvalid.ogg
12-20 04:13:22.940: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:22.940: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:22.940: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:22.950: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:22.950: E/SurfaceFlinger(49): glCheckFramebufferStatusOES error -1603666533
12-20 04:13:22.950: E/SurfaceFlinger(49): got GL_FRAMEBUFFER_COMPLETE_OES error while taking screenshot
12-20 04:13:22.950: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:22.950: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:38.110: E/AndroidRuntime(2540): FATAL EXCEPTION: main
12-20 04:13:38.110: E/AndroidRuntime(2540): Process: com.example.sabre1, PID: 2540
12-20 04:13:38.110: E/AndroidRuntime(2540): java.lang.NullPointerException
12-20 04:13:38.110: E/AndroidRuntime(2540): at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
12-20 04:13:38.110: E/AndroidRuntime(2540): at org.json.JSONTokener.nextValue(JSONTokener.java:94)
12-20 04:13:38.110: E/AndroidRuntime(2540): at org.json.JSONObject.<init>(JSONObject.java:155)
12-20 04:13:38.110: E/AndroidRuntime(2540): at org.json.JSONObject.<init>(JSONObject.java:172)
12-20 04:13:38.110: E/AndroidRuntime(2540): at com.example.sabre1.MainActivity.ListDrwaer(MainActivity.java:105)
12-20 04:13:38.110: E/AndroidRuntime(2540): at com.example.sabre1.MainActivity$JsonReadTask.onPostExecute(MainActivity.java:90)
12-20 04:13:38.110: E/AndroidRuntime(2540): at com.example.sabre1.MainActivity$JsonReadTask.onPostExecute(MainActivity.java:1)
12-20 04:13:38.110: E/AndroidRuntime(2540): at android.os.AsyncTask.finish(AsyncTask.java:632)
12-20 04:13:38.110: E/AndroidRuntime(2540): at android.os.AsyncTask.access$600(AsyncTask.java:177)
12-20 04:13:38.110: E/AndroidRuntime(2540): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
12-20 04:13:38.110: E/AndroidRuntime(2540): at android.os.Handler.dispatchMessage(Handler.java:102)
12-20 04:13:38.110: E/AndroidRuntime(2540): at android.os.Looper.loop(Looper.java:137)
12-20 04:13:38.110: E/AndroidRuntime(2540): at android.app.ActivityThread.main(ActivityThread.java:4998)
12-20 04:13:38.110: E/AndroidRuntime(2540): at java.lang.reflect.Method.invokeNative(Native Method)
12-20 04:13:38.110: E/AndroidRuntime(2540): at java.lang.reflect.Method.invoke(Method.java:515)
12-20 04:13:38.110: E/AndroidRuntime(2540): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
12-20 04:13:38.110: E/AndroidRuntime(2540): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
12-20 04:13:38.110: E/AndroidRuntime(2540): at dalvik.system.NativeStart.main(Native Method)
12-20 04:13:38.350: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:38.360: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:38.360: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:38.360: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:38.360: E/SurfaceFlinger(49): glCheckFramebufferStatusOES error -1603666533
12-20 04:13:38.360: E/SurfaceFlinger(49): got GL_FRAMEBUFFER_COMPLETE_OES error while taking screenshot
12-20 04:13:38.370: E/libEGL(49): called unimplemented OpenGL ES API
12-20 04:13:38.370: E/libEGL(49): called unimplemented OpenGL ES API
请帮忙。我已经被困了好几天了。感谢。
答案 0 :(得分：0)
问题在于你的回答。您未在doInBackground中收到服务器的回复。
对此方法（onPostExecute）检查此验证。
@Override
protected void onPostExecute(String result) {
if (jsonResult != null && jsonResult.equalsIgnoreCase("")) {
ListDrwaer();
}
}
更新后的代码：
并且在doInBackground中因为它是默认的返回类型，所以你应该这样做，而不是为JSON_RESPONSE声明全局变量。
// Async Task to access the web
private class JsonReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
String mResponse = "";
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
mResponse = inputStreamToString(response.getEntity().getContent()).toString();
} catch (ClientProtocolException e) {
mResponse = "";
e.printStackTrace();
} catch (IOException e) {
mResponse = "";
e.printStackTrace();
}
return mResponse;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
} catch (IOException e) {
// Yon must not refresh views from the doInBackground method.
// Toast.makeText(getApplicationContext(), "Error..." + e.toString(), Toast.LENGTH_LONG).show();
}
return answer;
}
@Override
protected void onPostExecute(String result) {
if (result != null && result.equalsIgnoreCase("")) {
ListDrwaer(result);
}
}
}// end async task