Legacy of screens - Android

Question

Wanted to create a screen(Activity) base for the android app I’m developing, so that all other screens inherited from this base. Thus, the screen would have an area reserved for the top of the page, a central region where the content will be variable and a footer area that would contain two buttons.
How could I do that?

Answer 1

Other answers have already given some alternatives, but I think I can add one more.

My suggestion would be to create a layout unique as being a template and use a real ViewStub to define the dynamic content of this template during the creation of Activity's.

For example:

xml template.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp">

    <!-- Aqui entra seu topo -->
    <include ... />

    <!-- O ViewStub guarda lugar para um layout
         a ser definido por quem usar -->
    <ViewStub android:id="@+id/stub"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:weight="1" />

    <!-- Aqui entra seu fundo -->
    <include ... />
</LinearLayout>

To dynamically change the layout during the creation of Activity just do:

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

    // Pode "setar" normalmente seu layout
    setContentView(R.layout.template);

    ViewStub vs = findViewById(R.id.stub);

    // Define qual o layout a ser inflado
    vs.setLayoutResource(R.layout.seuLayoutAtual);
    View conteudoPrincipal = vs.inflate();
}

Recalling that the ViewStub will leave the tree and will give way to every subtree that is defined in the layout you pass in the method ViewStub.setLayoutResource. The method inflate returns the root layout you inflated.

That way you reuse the same layout just changing the content you need.

---

For the question of function/behaviour belonging to the template, you can create a class, can be abstract if you prefer, that inherits from some subclass or own Activity (FragmentActivity, ListActivity and so on) to contain this behavior that is common to all.

You’d have something like:

public abstract class BaseActivity extends Activity {

    // Template method para retornar o conteudo
    // interno ao template.
    // Sendo abstrato para obrigar que a subclass forneca
    public abstract @LayoutRes int getContentLayoutId();

    // Metodo responsavel por configurar o conteudo do template
    public abstract void onCreateContent(View conteudo);

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

        setContentView(R.layout.template);

        ViewStub vs = findViewById(R.id.stub);

        // Define qual o layout a ser inflado
        vs.setLayoutResource(getContentLayoutId());
        View conteudoPrincipal = vs.inflate();

        // Configuracao de listener de eventos e etc

        // Deixa a subclasse configurar o conteudo
        onCreateContent(conteudoPrincipal);
    }

    // Metodos comuns
}

Where each Activity that will use the template define the content:

public class ActivityLoja extends BaseActivity {
    @Override
    public int getContentLayoutId() {
        return R.layout.loja;
    }

    @Override
    public void onCreateContent(View conteudo) {
        // Configuracao do conteudo
    }

    // Restante do codigo da sua Activity
}

public class ActivityCarrinho extends BaseActivity {
    @Override
    public int getContentLayoutId() {
        return R.layout.carrinho;
    }

    @Override
    public void onCreateContent(View conteudo) {
        // Configuracao do conteudo
    }

    // Restante do codigo da sua Activity
}

The record is normal, as if there was no inheritance:

<activity
    android:name=".activity.ActivityLoja"
    android:label="@string/loja" />

<activity
    android:name=".activity.ActivityCarrinho"
    android:name="@string/carrinho" />

Some references:

• http://developer.android.com/reference/android/view/ViewStub.html
• http://android-developers.blogspot.com.br/2009/03/android-layout-tricks-3-optimize-with.html

Answer 2

I believe you want to be a Screen Designer(XML) and not Screen(Activity) I’m right?

If that is your question then, you want to know how to do an old practice of reuse of layouts as well as good practice on web pages.

To make a screen or an xml layout that can be reused everywhere from the app, so it has a top one body and a footer.

do..

master_top.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ffffff"
android:padding="5dp" >

<ImageView
    android:id="@+id/imageView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_alignParentTop="true"
    android:layout_margin="5dp"
    android:src="@drawable/my_logo" />

</RelativeLayout>

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#f0f0f0" >


<include android:id="@+id/topo_view"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    layout="@layout/master_top" />

<LinearLayout
    android:id="@+id/linearLayout1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_margin="10dp"
    android:background="#ffffff"
    android:orientation="vertical"
    android:padding="5dp" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="$$$$$$$ CORPO $$$$$$$"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textColor="#1AA52F" />

</LinearLayout>

<include
    android:id="@+id/rodape_view"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    layout="@layout/master_footer" />

</RelativeLayout>

master_footer.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ffffff"
android:padding="5dp" >

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:gravity="center"
    android:text="-----------RODAPE---------------"
    android:textColor="#EFEFEF" />

</RelativeLayout>

...

You can also use < merge >

REF official website. http://developer.android.com/training/improving-layouts/reusing-layouts.html

Answer 3

Have it so, it would be like you do the opposite of example! In the example is just make a copy of (XML) and change the body and ready. But there is no escape, a part of the layout you will not get out of the work of doing.

To do this way you spoke just do the opposite.

Example:

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#ffffff"
    android:padding="5dp" >

    <!-- Top -->
    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_margin="5dp"
        android:src="@drawable/my_logo" />



<!-- Body -->
    <include android:id="@+id/topo_view"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        layout="@layout/my_body" />



    <!-- Footer --> 
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:gravity="center"
        android:text="-----------RODAPE---------------"
        android:textColor="#EFEFEF" />

    </RelativeLayout>

my_body.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:background="#f0f0f0" >


    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:background="#ffffff"
        android:orientation="vertical"
        android:padding="5dp" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@@@@@@@ MY BODY @@@@@@@@"
            android:textAppearance="?android:attr/textAppearanceLarge"
            android:textColor="#1AA52F" />

    </LinearLayout>


    </RelativeLayout>