安卓：我們無法根據一個片段導航到另一個

This is the login screen, which leads to the next screen(Chat Screen)安卓：我們無法根據一個片段導航到另一個

This is the Chat Screen- which I am unable to navigate to

我想實現一個聊天功能，其中兩個登錄和聊天屏幕是fragments.I我不是任何得到錯誤。但是，該應用沒有導航到聊天屏幕。我不知道我在哪裏失蹤。任何類型的建議，將不勝感激。

********登錄片段********

public class LoginFragment extends Fragment { 

private EditText mUsernameView; 
private Button signInButton; 
private String mUsername; 
private Socket mSocket; 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 

    View loginview = inflater.inflate(R.layout.fragment_login, container, false); 

    ChatApplication app = (ChatApplication) getActivity().getApplication(); 
    mSocket = app.getSocket(); 

    // this is the login form 
    mUsernameView = (EditText) loginview.findViewById(R.id.username_input); 
    mUsernameView.setOnEditorActionListener(new TextView.OnEditorActionListener() 
    { 
     @Override 
     public boolean onEditorAction(TextView textView, int id, KeyEvent keyEvent) 
     { 
      if(id == R.id.login || id == EditorInfo.IME_NULL) 
      { 
       attemptLogin(); 
       return true; 
      } 
       return false; 
     } 
    }); 

    signInButton = (Button) loginview.findViewById(R.id.sign_in_button); 
    signInButton.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) 
     { 
      attemptLogin(); 
     } 
    }); 

    mSocket.on("login",onLogin); 

    return loginview; 
} 

@Override 
public void onDestroy() { 
    super.onDestroy(); 

    mSocket.off("login", onLogin); 
} 

/* 
    This method attempts the following 
    1- clears the error message/resets the error message. 
    2- checks if the user has entered valid username 
    3- attempts user login 
*/ 
private void attemptLogin() 
{ 
    mUsernameView.setError(null); //1 
    String username = mUsernameView.getText().toString().trim(); 
    if(TextUtils.isEmpty(username)) //2 
    { 
     mUsernameView.setError("This field is required!"); 
     mUsernameView.requestFocus(); 
     return; 
    } 

    mUsername = username; 

    mSocket.emit("add user", username); //3 
} 

private Emitter.Listener onLogin = new Emitter.Listener() 
{ 
    @Override 
    public void call(Object... args) 
    { 
     JSONObject data = (JSONObject) args[0]; 
     int numUsers; 
     try 
     { 
      numUsers = data.getInt("numUsers"); 
     } 
     catch (JSONException e) 
     { 
      return; 
     } 

     Intent intent = new Intent(); 
     intent.putExtra("username",mUsername); 
     intent.putExtra("numUsers",numUsers); 
     getActivity().setResult(RESULT_OK,intent); 
     getActivity().finish(); 
    } 
};

}

**************聊天片段*************

public class ChatFragment extends Fragment 
{ 


    private static final int REQUEST_LOGIN = 1; 

    private static final int TYPING_TIMER_LENGTH = 600; 

    private RecyclerView mMessagesView; 
    private EditText mInputMessageView; 
    private List<Message> mMessages = new ArrayList<Message>(); 
    private RecyclerView.Adapter mAdapter; 
    private boolean mTyping = false; 
    private Handler mTypingHandler = new Handler(); 
    private String mUsername; 
    private Socket mSocket; 

    private Boolean isConnected = true; 

    public ChatFragment() { 
     super(); 
    } 

    @Override 
    public void onAttach(Context context) { 
     super.onAttach(context); 
     mAdapter = new MessageAdapter(context, mMessages); 
    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     setHasOptionsMenu(true); 

     ChatApplication app = (ChatApplication) getActivity().getApplication(); 
     mSocket = app.getSocket(); 
     mSocket.on(Socket.EVENT_CONNECT,onConnect); 
     mSocket.on(Socket.EVENT_DISCONNECT,onDisconnect); 
     mSocket.on(Socket.EVENT_CONNECT_ERROR, onConnectError); 
     mSocket.on(Socket.EVENT_CONNECT_TIMEOUT, onConnectError); 
     mSocket.on("new message", onNewMessage); 
     mSocket.on("user joined", onUserJoined); 
     mSocket.on("user left", onUserLeft); 
     mSocket.on("typing", onTyping); 
     mSocket.on("stop typing", onStopTyping); 
     mSocket.connect(); 

     startSignIn(); 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     return inflater.inflate(R.layout.fragment_chat, container, false); 
    } 

    @Override 
    public void onDestroy() { 
     super.onDestroy(); 

     mSocket.disconnect(); 

     mSocket.off(Socket.EVENT_CONNECT, onConnect); 
     mSocket.off(Socket.EVENT_DISCONNECT, onDisconnect); 
     mSocket.off(Socket.EVENT_CONNECT_ERROR, onConnectError); 
     mSocket.off(Socket.EVENT_CONNECT_TIMEOUT, onConnectError); 
     mSocket.off("new message", onNewMessage); 
     mSocket.off("user joined", onUserJoined); 
     mSocket.off("user left", onUserLeft); 
     mSocket.off("typing", onTyping); 
     mSocket.off("stop typing", onStopTyping); 
    } 

    @Override 
    public void onViewCreated(View view, Bundle savedInstanceState) { 
     super.onViewCreated(view, savedInstanceState); 

     mMessagesView = (RecyclerView) view.findViewById(R.id.messages); 
     mMessagesView.setLayoutManager(new LinearLayoutManager(getActivity())); 
     mMessagesView.setAdapter(mAdapter); 

     mInputMessageView = (EditText) view.findViewById(R.id.message_input); 
     mInputMessageView.setOnEditorActionListener(new TextView.OnEditorActionListener() { 
      @Override 
      public boolean onEditorAction(TextView v, int id, KeyEvent event) { 
       if (id == R.id.send || id == EditorInfo.IME_NULL) { 
        attemptSend(); 
        return true; 
       } 
       return false; 
      } 
     }); 
     mInputMessageView.addTextChangedListener(new TextWatcher() { 
      @Override 
      public void beforeTextChanged(CharSequence s, int start, int count, int after) { 
      } 

      @Override 
      public void onTextChanged(CharSequence s, int start, int before, int count) { 
       if (null == mUsername) return; 
       if (!mSocket.connected()) return; 

       if (!mTyping) { 
        mTyping = true; 
        mSocket.emit("typing"); 
       } 

       mTypingHandler.removeCallbacks(onTypingTimeout); 
       mTypingHandler.postDelayed(onTypingTimeout, TYPING_TIMER_LENGTH); 
      } 

      @Override 
      public void afterTextChanged(Editable s) { 
      } 
     }); 

     ImageButton sendButton = (ImageButton) view.findViewById(R.id.send_button); 
     sendButton.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       attemptSend(); 
      } 
     }); 
    } 

    @Override 
    public void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 
     if (Activity.RESULT_OK != resultCode) { 
      getActivity().finish(); 
      return; 
     } 

     mUsername = data.getStringExtra("username"); 
     int numUsers = data.getIntExtra("numUsers", 1); 

     addLog(getResources().getString(R.string.message_welcome)); 
     addParticipantsLog(numUsers); 
    } 

    @Override 
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     inflater.inflate(R.menu.menu_main, menu); 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_leave) { 
      leave(); 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 

    private void addLog(String message) { 
     mMessages.add(new Message.Builder(Message.TYPE_LOG) 
       .message(message).build()); 
     mAdapter.notifyItemInserted(mMessages.size() - 1); 
     scrollToBottom(); 
    } 

    private void addParticipantsLog(int numUsers) { 
     addLog(getResources().getQuantityString(R.plurals.message_participants, numUsers, numUsers)); 
    } 

    private void addMessage(String username, String message) { 
     mMessages.add(new Message.Builder(Message.TYPE_MESSAGE) 
       .username(username).message(message).build()); 
     mAdapter.notifyItemInserted(mMessages.size() - 1); 
     scrollToBottom(); 
    } 

    private void addTyping(String username) { 
     mMessages.add(new Message.Builder(Message.TYPE_ACTION) 
       .username(username).build()); 
     mAdapter.notifyItemInserted(mMessages.size() - 1); 
     scrollToBottom(); 
    } 

    private void removeTyping(String username) { 
     for (int i = mMessages.size() - 1; i >= 0; i--) { 
      Message message = mMessages.get(i); 
      if (message.getType() == Message.TYPE_ACTION && message.getUsername().equals(username)) { 
       mMessages.remove(i); 
       mAdapter.notifyItemRemoved(i); 
      } 
     } 
    } 

    private void attemptSend() { 
     if (null == mUsername) return; 
     if (!mSocket.connected()) return; 

     mTyping = false; 

     String message = mInputMessageView.getText().toString().trim(); 
     if (TextUtils.isEmpty(message)) { 
      mInputMessageView.requestFocus(); 
      return; 
     } 

     mInputMessageView.setText(""); 
     addMessage(mUsername, message); 

     // perform the sending message attempt. 
     mSocket.emit("new message", message); 
    } 

    private void startSignIn() { 
     mUsername = null; 
    /* Error: 
     Intent intent = new Intent(getActivity(), LoginFragment.class); 
     startActivityForResult(intent, REQUEST_LOGIN); 
    */ 

    // Solution 1: for calling a fragment from a fragment 
     Intent intent = new Intent(getActivity(),LoginFragment.class); 
     getActivity().startActivityForResult(intent,REQUEST_LOGIN); 

/* 
    // Solution 2: for calling a fragment from a fragment 
     LoginFragment loginFragment = new LoginFragment(); 
     FragmentManager fManager = getFragmentManager(); 
     FragmentTransaction fTransaction = fManager.beginTransaction(); 
     fTransaction.replace(R.id.id_fragment_chat,loginFragment); 
     fTransaction.addToBackStack(null); 
     fTransaction.commit(); 

*/ 
    } 

    private void leave() { 
     mUsername = null; 
     mSocket.disconnect(); 
     mSocket.connect(); 
     startSignIn(); 
    } 

    private void scrollToBottom() { 
     mMessagesView.scrollToPosition(mAdapter.getItemCount() - 1); 
    } 

    private Emitter.Listener onConnect = new Emitter.Listener() { 
     @Override 
     public void call(Object... args) { 
      getActivity().runOnUiThread(new Runnable() { 
       @Override 
       public void run() { 
        if(!isConnected) { 
         if(null!=mUsername) 
          mSocket.emit("add user", mUsername); 
         Toast.makeText(getActivity().getApplicationContext(), 
           R.string.connect, Toast.LENGTH_LONG).show(); 
         isConnected = true; 
        } 
       } 
      }); 
     } 
    }; 
. 
. 
. 
}

來源

2016-12-26 Meghana

應該有錯誤...'LoginFragment'不是一個活動。你不能使用'startActivity' –

不清楚你如何嘗試啓動'ChatFragment'，雖然 –

是的，LoginFragment不是一個活動.. – Meghana

關於您的private void startSignIn() { mUsername = null; Intent intent = new Intent(getActivity(), LoginFragment.class); startActivityForResult(intent, 0); } ...你想做什麼？開始另一項活動？然後你應該調用這個活動，並在這個活動中添加這個片段。或者，如果你想通過另一個相同的活動來替代一個片段，你應該這樣做，像這樣，而不是startActivity：

YourFragment fragment = new YourFragment(); 
     FragmentManager fragmentManager = getSupportFragmentManager(); 
     fragmentManager.beginTransaction() 
       .replace(R.id.fragmentContainer, fragment, YOUR_TAG) 
       .commit();

來源

2016-12-27 11:27:03 Hetfieldan24

使用核心片段結構，而不是使用直接的延伸

import android.support.v4.app.Fragment; 
import android.support.v4.app.FragmentManager; 

/** 
* 
* This is main core fragment. All fragment defined in this project that extends this fragment. 
* 
* @author viral 
* 
*/ 
public class CoreFragment extends Fragment { 

    private static FragmentManager fm; 
    private CharSequence tabTitle; 

    /** 
    * This method switch fragment. 
    * 
    * @param fragment - from fragment 
    * @param viewReplace - Destination view/container 
    * 
    */ 
    public void switchFragment(Fragment fragment, int viewReplace){ 
     try { 
      FragmentManager fragmentManager = getFragmentManager(); 
      if(fragmentManager != null) 
       fm = fragmentManager; 

      fm.beginTransaction() 
       .replace(viewReplace, fragment) 
       .commit(); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 

    /** 
    * This method switch fragment. 
    * 
    * @param fragment - from fragment 
    * @param viewReplace - Destination view/container 
    * 
    */ 
    public void switchFragmentWithBackstack(Fragment fragment, int viewReplace){ 
     try { 
      FragmentManager fragmentManager = getFragmentManager(); 
      if(fragmentManager != null) 
       fm = fragmentManager; 
      fm.beginTransaction() 
       .replace(viewReplace, fragment) 
       .addToBackStack(null) 
       .commit(); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 
}

然後根據您的應用要求使用switchFragment/switchFragmentWithBackstack方法。

你所有的分片擴展CoreFragment

來源

2016-12-27 13:16:10

安卓：我們無法根據一個片段導航到另一個

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