android - qué - que pasa si los neumaticos estan muy inflados

Cómo inflar la vista dentro del fragmento

Question

Si trato de inflar una vista dentro de un fragmento, obtengo NULL. Por ejemplo:

public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Here I will inflate my view using the layout ID & return.
return view;
}

Cada vez que se hace clic en un botón, necesito crear una vista dinámica, por ejemplo: button y agregar a LinearLayout. Me gustaría realizar esta operación dentro de mi clase de fragmento de esta manera:

public void addPlaces() {
Button button = new Button(null);
button.setText("button name");
// e.g. like adding button to enter code here linear layout
linearLayout.addView(button);
}

Entonces, si consigo inflar LinearLayout dentro de CreateView y usarlo en agregar clase, obtengo NULL. ¿Como alcanzar?

Answer 1

Declare la variable como una variable de instancia y luego inicialice el diseño lineal

LinearLayout linearLayout;
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment1, container, false);
linearLayout = (LinearLayout) rootView.findViewById(R.id.linearlayout);
return rootView;
}

Entonces

public void addPlaces() {
Button button = new Button(getActivity());
// needs activity context
// fragment hosted by a activity. use getActivity() to get the context of the hosting activity.
button.setText("button name");
linearlayout.addView(button);
}

Ejemplo: Modifique el siguiente según sus requisitos.

fragment1.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="Button" />
<LinearLayout
android:layout_width="fill_parent"
android:id="@+id/linearlayout"
android:layout_height="fill_parent"
android:layout_above="@+id/button1"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:orientation="vertical" >
</LinearLayout>
</RelativeLayout>

Myfragment.java

public class Myfragment extends Fragment {
LinearLayout linearLayout;
View rootView;
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Button b = (Button) rootView.findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
addPlaces();
}
});
linearLayout = (LinearLayout) rootView.findViewById(R.id.linearlayout);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment1, container, false);
return rootView;
}
public void addPlaces() {
Button button = new Button(getActivity()); // needs activity context
button.setText("button name");
linearLayout.addView(button);
}
}

Toma instantánea de mi emulador

Editar:

activity-main.xml

<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" >
<fragment android:name="com.example.fragments.Myfragment"
android:id="@+id/frag"
android:layout_above="@+id/button1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:text="Button" />
</RelativeLayout>

MainActivity.java

public class MainActivity extends FragmentActivity {
Button b;
Myfragment fragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragment = new Myfragment();
fragmentTransaction.add(R.id.frag, fragment);
fragmentTransaction.commit();
b = (Button) findViewById(R.id.button1);
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
fragment.addPlaces();
}
});
}
}

Myfragment.java

public class Myfragment extends Fragment {
LinearLayout linearLayout;
View rootView;
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
linearLayout = (LinearLayout) rootView.findViewById(R.id.linearlayout);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment1, container, false);
return rootView;
}
public void addPlaces() {
Button button = new Button(getActivity()); // needs activity context
button.setText("button name");
linearLayout.addView(button);
}
}