Question

I’m developing a program that mainly consists of 3 tabs, and I follow this tutorial to create the tabs. The problem I’ve faced is that when I want to align a button to the center of the tab, it is aligned only as horizontal-center (I need it to be centered both vertically and horizontally):

How can I fix this problem? Am I using the tabs in right way?

Here is my source code:

MainActivity.java

public class MainActivity extends TabActivity
{

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Resources res = getResources(); // Resource object to get Drawables
        TabHost tabHost = getTabHost();  // The activity TabHost
        TabHost.TabSpec spec;  // Resusable TabSpec for each tab
        Intent intent;  // Reusable Intent for each tab

        // Create an Intent to launch an Activity for the tab (to be reused)
        intent = new Intent().setClass(this, HomeActivity.class);

        // Initialize a TabSpec for each tab and add it to the TabHost
        spec = tabHost.newTabSpec("home").setIndicator("Home",
                          res.getDrawable(R.drawable.ic_tab_home))
                      .setContent(intent);
        tabHost.addTab(spec);

        // Do the same for the other tabs

        tabHost.setCurrentTab(0);
    }
}

---

HomeActivitiy.java

public class HomeActivity extends Activity
{
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.home);
    }
}

---

main.xml

<?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <LinearLayout
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:padding="5dp">
        <TabWidget
            android:id="@android:id/tabs"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content" />
        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:padding="5dp" >
        </FrameLayout>
    </LinearLayout>
</TabHost>

---

home.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <Button android:text="OPEN" android:id="@+id/btnOpen"
          android:gravity="center"
          android:layout_gravity="center"
          android:layout_width="100dp"
          android:layout_height="100dp">
  </Button>
</LinearLayout>

Answer 1

<?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:text="OPEN" 
          android:id="@+id/btnOpen"
          android:layout_centerInParent="true"
          android:layout_width="100dp"
          android:layout_height="100dp">
  </Button>
</RelativeLayout>

try using RelativeLayout.