我目前正在创建一个应用程序，它应该从服务器收集JSONObjects（或Groups），然后在ListView中打印它们。我成功解析了JSONObjects并可以遍历并打印LogCat中的所有组名，但是当我尝试填充ListView时，它总是空出来。
这是我连接到服务器的TCPConnection类：
public class TCPConnection {
private Controller controller;
private RunOnThread thread;
private Receive receive;
private Socket socket;
private DataInputStream input;
private DataOutputStream output;
private InetAddress address;
private int connectionPort;
private String ip;
private Exception exception;
private MainActivity main;
private static String id;
public TCPConnection(String ip, int connectionPort, MainActivity main) {
this.ip = ip;
this.connectionPort = connectionPort;
this.main = main;
thread = new RunOnThread();
}
public void setController(Controller controller) {
this.controller = controller;
}
public void connect() {
thread.start();
thread.execute(new Connect());
}
public void disconnect() {
thread.execute(new Disconnect());
}
public void newMessage(final String answer) {
main.runOnUiThread(new Runnable() {
public void run() {
String message = answer;
String type;
JSONObject jObj = null;
try {
jObj = new JSONObject(message);
type = jObj.getString("type");
if(type.equals("register")){
recieveID(jObj);
} else if(type.equals("groups")){
getAllGroups(jObj);
}else{
Log.i("TCPConnection", "Type does not exist");
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
}
//SENDING JOBJ to CONTROLLER
public void getAllGroups(JSONObject jObj){
Log.i("GRUPPER", "Jobj sent to controller");
controller.setAllGroups(jObj);
}
private class Receive extends Thread {
public void run() {
String result;
try {
while (receive != null) {
result = input.readUTF();
newMessage(result);
}
} catch (Exception e) { // IOException, ClassNotFoundException
receive = null;
}
}
}
private class Connect implements Runnable {
public void run() {
try {
Log.d("TCPConnection","Connect-run");
address = InetAddress.getByName(ip);
Log.d("TCPConnection-Connect","Skapar socket");
socket = new Socket(address, connectionPort);
Log.d("TCP-CONNECT", "SOCKET INITIALIZED");
input = new DataInputStream(socket.getInputStream());
Log.d("TCP-CONNECT", "INPUTSTREAM INITIALIZED");
output = new DataOutputStream(socket.getOutputStream());
output.flush();
Log.d("TCPConnection-Connect","Strömmar klara");
receive = new Receive();
receive.start();
} catch (Exception e) { // SocketException, UnknownHostException
Log.d("TCPConnection-Connect",e.toString());
exception = e;
}
}
}
public class Disconnect implements Runnable {
public void run() {
try {
if (socket != null)
socket.close();
if (input != null)
input.close();
if (output != null)
output.close();
thread.stop();
socket.close();
} catch(IOException e) {
exception = e;
}
}
}
public void send(String JSONQuery) {
thread.execute(new Send(JSONQuery));
}
public class Send implements Runnable {
final String JSONQuery;
public Send(String JSONQuery) {
this.JSONQuery = JSONQuery;
}
public void run() {
try {
output.writeUTF(JSONQuery);
output.flush();
} catch (IOException e) {
exception = e;
newMessage("EXCEPTION");
}
}
}
然后我有我的控制器：
public class Controller {
private MainActivity activity;
private CommunityFragment communityFragment;
private TCPConnection connection;
private boolean connected = false;
ArrayList<String> groupList = new ArrayList<String>();
public Controller() {
}
public Controller(MainActivity activity, CommunityFragment communityFragment, TCPConnection connection) {
this.activity = activity;
this.communityFragment = communityFragment;
communityFragment.setController(this);
this.connection = connection;
connection.setController(this);
connect();
}
public void allGroups() {
StringWriter stringWriter = new StringWriter();
JsonWriter jsonWriter = new JsonWriter(stringWriter);
Log.i("MyConnectService", "setAllGroups() kördes");
try {
jsonWriter.beginObject().name("type").value("groups").endObject();
} catch (IOException e) {
e.printStackTrace();
Log.e("MyConnectService", "setAllGroups fail");
}
connection.send( stringWriter.toString());
}
public void setAllGroups(JSONObject jObj) {
Log.i("GRUPPER", "groupList iteration start");
groupList.add("TEST");
try {
JSONArray jsonArr = jObj.getJSONArray("groups");
for (int i = 0; i < jsonArr.length(); i++) {
Log.d("GRUPPER", "RECIEVED IN LOOP: " + jsonArr.getJSONObject(i).getString("group"));
groupList.add(jsonArr.getJSONObject(i).getString("group").toString());
}
} catch (Exception e) {
Log.i("GRUPPER", "error in getMembers() for " + e);
}
Log.i("GRUPPER", "groupList iteration - Done!");
}
public ArrayList<String> getGroupList(){
Log.i("GRUPPER", "groupList collected by communityFrag");
return groupList;
}
}
这是我的CommunityFragment，它包含listView，这也是你创建组的地方
public class CommunityFragment extends Fragment {
private Controller controller = new Controller();
private EditText etGroup;
private EditText etMember;
private Button btnSave;
private ListView lvGroups;
private String groupName, userName;
private ArrayAdapter<String> mArrayAdapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_community, container, false);
initializeComponents(rootView);
// controller.allGroups();
initializeAdapter();
return rootView;
}
public void setController(Controller controller) {
this.controller = controller;
}
private void initializeComponents(View rootView) {
.
.
.
}
});
}
public void initializeAdapter() {
ArrayList<String> groupList = controller.getGroupList();
//Adapter definierad och sätts till list fragmentet
mArrayAdapter = new GroupAdapter(getActivity(), R.id.lv_groups, groupList);
lvGroups.setAdapter(mArrayAdapter);
Log.i("GRUPPER", "Adapter created");
}
}
这是GroupAdapter：
public class GroupAdapter extends ArrayAdapter<String> {
private ArrayList<String> ArrayListGroups;
private int Resource;
private Context context;
private LayoutInflater vi;
public GroupAdapter(Context context, int resource, ArrayList<String> objects) {
super(context, resource, objects);
ArrayListGroups = objects;
Resource = resource;
this.context = context;
vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if(convertView==null){
convertView = vi.inflate(Resource, null);
//recycling views using viewholder (items getting offscreen)
holder = new ViewHolder();
holder.groupName = (TextView) convertView.findViewById(R.id.tv_list_title);
convertView.setTag(holder);
}else{
holder = (ViewHolder)convertView.getTag();
}
//setting text in each item based on the position in the list
holder.groupName.setText(ArrayListGroups.get(position));
return convertView;
}
static class ViewHolder{
public TextView groupName;
}
public void updateList(){
notifyDataSetChanged();
}
}
这是LogCat：
10-29 13:34:32.962 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ onVisibilityChanged() is called, visibility : 4
10-29 13:34:32.962 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:33.002 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ onVisibilityChanged() is called, visibility : 0
10-29 13:34:33.002 31680-31699/se.mah.sofand.mapapplication D/TCP-CONNECT﹕ SOCKET INITIALIZED
10-29 13:34:33.002 31680-31699/se.mah.sofand.mapapplication D/TCP-CONNECT﹕ INPUTSTREAM INITIALIZED
10-29 13:34:33.002 31680-31699/se.mah.sofand.mapapplication D/TCPConnection-Connect﹕ Strömmar klara
10-29 13:34:33.002 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:33.122 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:33.142 31680-31680/se.mah.sofand.mapapplication I/Adreno-EGL﹕ <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: ()
OpenGL ES Shader Compiler Version: E031.24.00.08+13
Build Date: 03/20/14 Thu
Local Branch: 0320_AU200_patches
Remote Branch:
Local Patches:
Reconstruct Branch:
10-29 13:34:33.182 31680-31680/se.mah.sofand.mapapplication D/OpenGLRenderer﹕ Enabling debug mode 0
10-29 13:34:33.202 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:144 height:144 bitmap id is 199
10-29 13:34:33.202 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:144 height:144 bitmap id is 200
10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ onVisibilityChanged() is called, visibility : 4
10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
**10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication I/GRUPPER﹕ Jobj sent to controller
10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication I/GRUPPER﹕ groupList iteration start
10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication D/GRUPPER﹕ RECIEVED IN LOOP: blajje
10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication I/GRUPPER﹕ groupList iteration - Done!**
10-29 13:34:33.212 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:96 height:96 bitmap id is 201
10-29 13:34:33.312 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:33.322 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:35.162 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ onVisibilityChanged() is called, visibility : 0
10-29 13:34:35.162 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:35.992 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:36.022 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 203
10-29 13:34:36.022 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 204
10-29 13:34:36.022 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 205
10-29 13:34:36.032 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 206
10-29 13:34:36.032 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 207
10-29 13:34:36.032 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 208
10-29 13:34:36.032 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 209
10-29 13:34:36.042 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 210
10-29 13:34:36.042 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 211
10-29 13:34:36.042 31680-31680/se.mah.sofand.mapapplication D/skia﹕ GFXPNG PNG bitmap created width:78 height:96 bitmap id is 212
10-29 13:34:36.062 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ Get MotionRecognitionManager
**10-29 13:34:36.062 31680-31680/se.mah.sofand.mapapplication I/GRUPPER﹕ groupList collected by communityFrag
10-29 13:34:36.062 31680-31680/se.mah.sofand.mapapplication I/GRUPPER﹕ Adapter created**
10-29 13:34:36.062 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:36.082 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
10-29 13:34:36.382 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ onVisibilityChanged() is called, visibility : 4
10-29 13:34:36.382 31680-31680/se.mah.sofand.mapapplication D/AbsListView﹕ unregisterIRListener() is called
注意只创建了一个组，这就是为什么只有＆＃39; blajje＆＃39;是可见的。
如您所见，列表是在创建适配器之前定义的，但我仍然无法显示它。没有Nullpointer或其他异常发生。有什么想法吗？
答案 0 :(得分：0)
您在此处使用的控制器
public void initializeAdapter() {
ArrayList<String> groupList = controller.getGroupList();
未设置为使用任何数据。它被初始化（= new Controller()），但之后你什么也没做。它没有数据可供使用。我认为你必须在这里使用你在Controller类中创建的方法
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_community, container, false);
initializeComponents(rootView);
// controller.allGroups();
controller.setAllGroups(); // this line should set the data
initializeAdapter();
return rootView;
}
如果控制器实例没有数据集，则没有数据传递给列表适配器，因此不会显示任何数据。
修改
您使用的Controller实例初始化为
private Controller controller = new Controller();
但是，Controller类有2个构造函数
public Controller() {
}
public Controller(MainActivity activity, CommunityFragment communityFragment, TCPConnection connection) {
this.activity = activity;
this.communityFragment = communityFragment;
communityFragment.setController(this);
this.connection = connection;
connection.setController(this);
connect();
}
您似乎使用了错误的构造函数，因为您当前使用的空构造函数不会初始化TCPConnection实例connection。
如果使用正确的构造函数初始化Controller实例，则该nullpointer将消失。
答案 1 :(得分：0)
I have checked the code, find that in this part:
public class CommunityFragment extends Fragment {
private Controller controller = new Controller();
}
When you init Controller, you should use this constructor
public Controller(MainActivity activity, CommunityFragment communityFragment, TCPConnection connection)
{
this.activity = activity;
this.communityFragment = communityFragment;
communityFragment.setController(this);
this.connection = connection;
connection.setController(this);
connect();
}
You can try this.