Accessing EditText Android

Question

I have a MainActivity with activity_main Layout. in activity_main layout i have 4 Fragments. in one of these fragments i have 2 text box and 1 button. its a login form. when i click on this button i want to know what is that text inside textbox. in MainActivity i defined Textbox with findviewbyid. but when i click on button i cant get text inside text view.

what should i do?

activity_main :

<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.decoration.MainActivity"
tools:ignore="MergeRootFrame"
android:background="#FFFFFF" 
android:orientation="horizontal"
android:focusableInTouchMode="true">

   <TableRow android:layout_weight="1" 
       android:gravity="top">


    <fragment
        android:id="@+id/UpLeft"
        android:name="com.example.decoration.UpLeftFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1" 
        android:gravity="left"  />




    <fragment
        android:id="@+id/UpRight"
        android:name="com.example.decoration.UpRightFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
                    android:gravity="right"  />


   </TableRow>


   <TableRow android:layout_weight="1"
       android:gravity="bottom" >



    <fragment
        android:id="@+id/DownLeft"
        android:name="com.example.decoration.DownLeftFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1" 
                    android:gravity="left" />



       <fragment
        android:id="@+id/DownRight"
        android:name="com.example.decoration.DownRightFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1" 
                    android:gravity="right" />

   </TableRow>

down_left_fragment :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="0px"
android:layout_height="match_parent"
android:layout_gravity="top"
android:background="#761F01"
android:orientation="vertical" >

    <ImageView
        android:id="@+id/imageview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:scaleType="fitXY"
        android:src="@drawable/bottomleft" />

<EditText
    android:id="@+id/Usernme"
    android:layout_width="150dp"
    android:layout_height="30dp"
    android:layout_gravity="center"
    android:background="@drawable/txtedges"
    android:gravity="center"
    android:hint="Username"
    android:inputType="text"
    android:singleLine="true" />

   <TextView 
    android:layout_width="wrap_content"
    android:layout_height="3dp"/>

<EditText
    android:id="@+id/Password"
    android:layout_width="150dp"
    android:layout_height="30dp"
    android:layout_gravity="center"
    android:background="@drawable/txtedges"
    android:gravity="center"
    android:hint="Password"
    android:inputType="textPassword"
    android:singleLine="true" />

    <TextView 
    android:layout_width="wrap_content"
    android:layout_height="3dp"/>

<Button
    android:id="@+id/SignInBtn"
    android:layout_width="150dp"
    android:layout_height="30dp"
    android:layout_gravity="center"
    android:background="@drawable/btnedges"
    android:text="SignIn"
    android:textColor="#FFFFFF" />

<CheckBox
    android:id="@+id/Save"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:checked="true"
    android:gravity="right|end"
    android:text="Save"
    android:textColor="#F7BA00" />

DownLeftFragment.java :

public class DownLeftFragment extends Fragment{

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

MainActivity :

public class MainActivity extends Activity {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
        final EditText a = (EditText) findViewById (R.id.Username);
    Button Login = (Button) findViewById(R.id.SignInBtn);
    Login.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v)
            {
            StrictMode.setThreadPolicy(policy); 
            String n = a.getText().toString();
            login(n);
            }
    });


public void login(String a)
{...
}

Answer 1

Don't get a new reference of the EditText inside your onClick(), because it will be a different object as the one where the user has done the input.

In addition, as ElDuderino suggested, if you have a layout for a Fragment get the instance of the Views with findViewById(..) in your Fragment. This way if the View isn't needed anymore it can be gargabe collected along with the Fragment. Otherwise it will be alive as long the Activity is.

Edit:

Try this in your Fragment:

public class DownLeftFragment extends Fragment {

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

    @Override
    public View onCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        View root = inflater.inflate(R.layout.down_left_fragment,  container, false);
        EditText edit = (EditText) findViewById (R.id.Username);
        Button login = (Button) findViewById(R.id.SignInBtn);
        login.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                StrictMode.setThreadPolicy(policy); 
                String n = edit.getText().toString();
                login(n);
             }
        });

        return root;
    }
    public void login(String a) {
         ...
    }
}

Your MainActivity looks like this now:

public class MainActivity extends Activity {

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    }
}

This way all VIews belong to the Fragment which inflates the specific layout.