我在编程方面真的很新。我正在使用标签创建应用程序，每个标签都是一个片段，在此标签的一个标签中，我想将一些数据发送到服务器。这里是代码，看起来像所有的get（）函数在片段下不起作用。 （我已经解决了这个问题）现在程序无法运行。
这是我的代码
public class TabActivityMain extends Fragment implements OnClickListener {
TextView tvIsConnected;
EditText etName,etCountry,etTwitter;
Button btnPost;
Person person;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View V = inflater.inflate(R.layout.activity_tab_activity_main, container, false);
tvIsConnected = (TextView) V.findViewById(R.id.tvIsConnected);
etName = (EditText) V.findViewById(R.id.etName);
etCountry = (EditText) V.findViewById(R.id.etCountry);
etTwitter = (EditText) V.findViewById(R.id.etTwitter);
btnPost = (Button) V.findViewById(R.id.btnPost);
// check if you are connected or not
if(isConnected()){
tvIsConnected.setBackgroundColor(0xFF00CC00);
tvIsConnected.setText("You are conncted");
}
else{
tvIsConnected.setText("You are NOT conncted");
}
// add click listener to Button "POST"
btnPost.setOnClickListener(this);
return V;
}
public static String POST(String url, Person person){
InputStream inputStream = null;
String result = "";
try {
// 1. create HttpClient
HttpClient httpclient = new DefaultHttpClient();
// 2. make POST request to the given URL
HttpPost httpPost = new HttpPost(url);
String json = "";
// 3. build jsonObject
JSONObject jsonObject = new JSONObject();
jsonObject.accumulate("name", person.getName());
jsonObject.accumulate("country", person.getCountry());
jsonObject.accumulate("twitter", person.getTwitter());
// 4. convert JSONObject to JSON to String
json = jsonObject.toString();
// ** Alternative way to convert Person object to JSON string usin Jackson Lib
// ObjectMapper mapper = new ObjectMapper();
// json = mapper.writeValueAsString(person);
// 5. set json to StringEntity
StringEntity se = new StringEntity(json);
// 6. set httpPost Entity
httpPost.setEntity(se);
// 7. Set some headers to inform server about the type of the content
httpPost.setHeader("Accept", "application/json");
httpPost.setHeader("Content-type", "application/json");
// 8. Execute POST request to the given URL
HttpResponse httpResponse = httpclient.execute(httpPost);
// 9. receive response as inputStream
inputStream = httpResponse.getEntity().getContent();
// 10. convert inputstream to string
if(inputStream != null)
result = convertInputStreamToString(inputStream);
else
result = "Did not work!";
} catch (Exception e) {
Log.d("InputStream", e.getLocalizedMessage());
}
// 11. return result
return result;
}
public boolean isConnected(){
ConnectivityManager connMgr = (ConnectivityManager) getActivity().getSystemService(Activity.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isConnected())
return true;
else
return false;
}
@Override
public void onClick(View view) {
switch(view.getId()){
case R.id.btnPost:
if(!validate())
Toast.makeText(getActivity().getBaseContext(), "Enter some data!", Toast.LENGTH_LONG).show();
// call AsynTask to perform network operation on separate thread
new HttpAsyncTask().execute("http://hmkcode.appspot.com/jsonservlet");
break;
}
}
private class HttpAsyncTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
person = new Person();
person.setName(etName.getText().toString());
person.setCountry(etCountry.getText().toString());
person.setTwitter(etTwitter.getText().toString());
return POST(urls[0],person);
}
// onPostExecute displays the results of the AsyncTask.
@Override
protected void onPostExecute(String result) {
Toast.makeText(getActivity().getBaseContext(), "Data Sent!", Toast.LENGTH_LONG).show();
}
}
private boolean validate(){
if(etName.getText().toString().trim().equals(""))
return false;
else if(etCountry.getText().toString().trim().equals(""))
return false;
else if(etTwitter.getText().toString().trim().equals(""))
return false;
else
return true;
}
private static String convertInputStreamToString(InputStream inputStream) throws IOException{
BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(inputStream));
String line = "";
String result = "";
while((line = bufferedReader.readLine()) != null)
result += line;
inputStream.close();
return result;
}
}
并且log cat信息是
09-09 09:30:59.907: E/AndroidRuntime(1311): FATAL EXCEPTION: main
09-09 09:30:59.907: E/AndroidRuntime(1311): Process: com.zanqi.mainpage1, PID: 1311
09-09 09:30:59.907: E/AndroidRuntime(1311): java.lang.SecurityException: ConnectivityService: Neither user 10063 nor current process has android.permission.ACCESS_NETWORK_STATE.
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.os.Parcel.readException(Parcel.java:1465)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.os.Parcel.readException(Parcel.java:1419)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.net.IConnectivityManager$Stub$Proxy.getActiveNetworkInfo(IConnectivityManager.java:813)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.net.ConnectivityManager.getActiveNetworkInfo(ConnectivityManager.java:563)
09-09 09:30:59.907: E/AndroidRuntime(1311): at com.zanqi.mainpage1.TabActivityMain.isConnected(TabActivityMain.java:128)
09-09 09:30:59.907: E/AndroidRuntime(1311): at com.zanqi.mainpage1.TabActivityMain.onCreateView(TabActivityMain.java:58)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.support.v4.app.Fragment.performCreateView(Fragment.java:1504)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:942)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1121)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1484)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:482)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.support.v4.app.FragmentTabHost.onAttachedToWindow(FragmentTabHost.java:283)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.View.dispatchAttachedToWindow(View.java:12585)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2458)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2465)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2465)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.ViewGroup.dispatchAttachedToWindow(ViewGroup.java:2465)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1217)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.Choreographer.doFrame(Choreographer.java:544)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.os.Handler.handleCallback(Handler.java:733)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.os.Handler.dispatchMessage(Handler.java:95)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.os.Looper.loop(Looper.java:136)
09-09 09:30:59.907: E/AndroidRuntime(1311): at android.app.ActivityThread.main(ActivityThread.java:5017)
09-09 09:30:59.907: E/AndroidRuntime(1311): at java.lang.reflect.Method.invokeNative(Native Method)
09-09 09:30:59.907: E/AndroidRuntime(1311): at java.lang.reflect.Method.invoke(Method.java:515)
09-09 09:30:59.907: E/AndroidRuntime(1311): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
09-09 09:30:59.907: E/AndroidRuntime(1311): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
09-09 09:30:59.907: E/AndroidRuntime(1311): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：2)
return V;
必须位于函数的末尾，因为返回总是会退出函数并停止编译其余代码。
至于你的Logcat：添加
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
位于AndroidManifest.xml文件中的应用程序标记上方。
答案 1 :(得分：1)
当您不再参加活动时，您需要为大多数这些功能设置上下文。
例如，findViewByID需要知道要查看的视图。
因此，在您的示例中，您将使用
V.findViewByID(..)
虽然通常你会使用getView（）。findViewByID
而在另一种情况下，你一直在寻找
getActivity().getSystemService
以下是获取上下文的不同方法的一个很好的解释： https://stackoverflow.com/a/9606712/3009199
通常onCreateView看起来像这样：
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.activity_tab_activity_main, container, false);
}
然后将onCreateView中的其余代码移动到onActivityCreated
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
//...more code goes here and you can easily just do getView().findViewByID
}
请注意你的回归V;被称为早期回归。一旦方法命中一个return语句，它就会执行它并且该方法中的其余代码“死”。
此外，您不应该访问AsyncTask中的UI线程。 AsyncTask正在打开一个新线程，并不一定能访问UI。因此，您应该将包含所有人员详细信息的对象传递到AsyncTask中。
最后一件事，这是偏好或风格，我相信人们会不同意。我会说作为新手避免if和while语句没有大括号是一个好习惯：
为：
if(whatever == 1)
//blah blah
相反，你应该隐含你的括号：
好：
if(whatever == 1){
//blah blah
}