Fragments inside LinearLayout - Android

Question

I'm new with fragments and I try to use these. My xml from activity is:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Loguin"
tools:ignore="MergeRootFrame">

    <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Fragment Test"
    android:id="@+id/btn_FragmentTest"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="20dp"
    android:layout_marginBottom="0dp" />

    <LinearLayout
    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:orientation="horizontal"
    android:id="@+id/frgContainer"
    android:layout_marginTop="20dp">

    <fragment
        android:id="@+id/frgLoguin"
        android:layout_marginTop="20dp"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:name="habitatprojects.hubbuildings.Loguin$PlaceholderFragment"
        tools:layout="@layout/fragment_loguin" />

    </LinearLayout>



</LinearLayout>

And I want to change the fragment inside of LinearLayout, my class of mainActivity is:

public class Loguin extends Activity {

private int num = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_loguin);
    if (savedInstanceState == null) {
        getFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment())
                .commit();
    }

    Button btnBoton1 = (Button)findViewById(R.id.btn_FragmentTest);

    btnBoton1.setOnClickListener(new View.OnClickListener() {
        public void onClick(View arg0)
        {
            FragmentManager fragmentManager = getFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

            if(num==0)
            {
                fragmentTransaction.replace(R.id.frgContainer, new PlaceholderFragment())
                        .commit();

                num++;
            }
            else{
                if(num==1)
                {
                    fragmentTransaction.replace(R.id.frgContainer, new PlaceholderFragment2())
                            .commit();

                    num++;
                }
                else{
                    fragmentTransaction.replace(R.id.frgContainer, new PlaceholderFragment3())
                            .commit();

                    num = 0;
                }
            }
        }
    });
 }

And my PlaceHolderFunctions are:

public static class PlaceholderFragment extends Fragment {

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

public static class PlaceholderFragment2 extends Fragment {

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

public static class PlaceholderFragment3 extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_blank2, container, false);
    }
}

Why doesn't work when I press the button? What do I doing bad? Srry for my english and thanks in advance!

PD: If you need more code or info advise me, thanks!

PD1: When I debug with my device the log cat just say me:

11-18 11:33:30.775 6065-6065/habitatprojects.hubbuildings I/ViewRootImpl﹕ ViewRoot's Touch Event: Touch Down 11-18 11:33:30.835 6065-6065/habitatprojects.hubbuildings I/ViewRootImpl﹕ ViewRoot's Touch Event: Touch UP

Answer 1

Solved I just need to change my LinearLayout for FrameLayout! Thanks for all!

Answer 2

It's this easy:

It's very likely your main activity would look like this. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <LinearLayout
        android:id="@+id/your_vertical_list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">
    </LinearLayout>
</ScrollView>

Say you have a fragment OneRow .

Here's how you would add three rows.

private void addRows() {
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    ft.add(R.id.your_vertical_list, new OneRow());
    ft.add(R.id.your_vertical_list, new OneRow());
    ft.add(R.id.your_vertical_list, new OneRow());
    ft.commit();
}

Note that in .add you simply pass in the layout id, R.id.your_vertical_list .

Normally you'd need the rows, hence

public class MainActivity extends AppCompatActivity {

    ArrayList<OneRow> rows = new ArrayList<OneRow>();

    private void addRows() {
        FragmentTransaction ft =
          getSupportFragmentManager().beginTransaction();
        for (int i = 0; i < 20; i++) {
            OneRow r = new OneRow();
            rows.add(r);
            ft.add(R.id.your_vertical_list, r);
        }
        ft.commit();
    }

However. Note that it's usually better to commit for each item , especially if you are setting any text labels etc. For example

    private void addRows() {
        for (int i = 0; i < 20; i++) {
            FragmentTransaction ft =
              getSupportFragmentManager().beginTransaction();
            OneRow r = new OneRow();
            r.set
            rows.add(r);
            ft.add(R.id.your_vertical_list, r);
            ft.commit();
        }
    }