Android Development
Interview Questions
You'll Most Likely Be Asked
Job Interview Questions Series
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Android Development Interview Questions You'll Most Likely Be Asked
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9. Binding to Data with AdapterView
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Android Development Interview Questions
Review these typical interview questions and think about how you would answer them. Read the answers listed; you will find best possible answers along with strategies and suggestions.
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1: How to declare an activity in the manifest?
Answer:
In order to declare your activity, open your manifest file and add an <activity> element as a child of the <application> element. For example::
<manifest ... >
<application ... >
<activity android:name=".ExampleActivity" />
...
</application ... >
...
</manifest >
2: How can an activity include intent filters?
Answer:
An activity can include intent filter like this:
<activity android:name=".ExampleActivity" android:icon="@drawable/app_icon">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
3: How to start an activity?
Answer:
Activity can be started as:
Intent intent = new Intent(this, SignInActivity.class);
startActivity(intent);
4: How can a user send an email message with the intent? Explain with an example.
Answer:
Example is as under:
Intent intent = new Intent(Intent.ACTION_SEND);
intent.putExtra(Intent.EXTRA_EMAIL, recipientArray);
startActivity(intent);
5: How to start an activity for a result?
Answer:
Sometimes we need to start an activity for a result. An example is given below:
private void pickContact() {
// Create an intent to "pick" a contact, as defined by the content provider URI
Intent intent = new Intent(Intent.ACTION_PICK, Contacts.CONTENT_URI);
startActivityForResult(intent, PICK_CONTACT_REQUEST);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// If the request went well (OK) and the request was PICK_CONTACT_REQUEST
if (resultCode == Activity.RESULT_OK && requestCode == PICK_CONTACT_REQUEST) {
// Perform a query to the contact's content provider for the contact's name
Cursor cursor = getContentResolver().query(data.getData(),
new String[] {Contacts.DISPLAY_NAME}, null, null, null);
if (cursor.moveToFirst()) { // True if the cursor is not empty
int columnIndex = cursor.getColumnIndex(Contacts.DISPLAY_NAME);
String name = cursor.getString(columnIndex);
// Do something with the selected contact's name...
}
}
}
6: How to shut Down an Activity?
Answer:
There can be two different ways to do so. By calling its finish() method and also by finishActivity().
7: In how many different states can an activity exist?
Answer:
There are three different states in which an activity can exist. Resumed, Paused and Stopped.
8: How to implement the lifecycle callbacks?
Answer:
Lifecycle callbacks can be implemented as:
public class ExampleActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// The activity is being created.
}
@Override
protected void onStart() {
super.onStart();
// The activity is about to become visible.
}
@Override
protected void onResume() {
super.onResume();
// The activity has become visible (it is now "resumed").
}
@Override
protected void onPause() {
super.onPause();
// Another activity is taking focus (this activity is about to be "paused").
}
@Override
protected void onStop() {
super.onStop();
// The activity is no longer visible (it is now "stopped")
}
@Override
protected void onDestroy() {
super.onDestroy();
// The activity is about to be destroyed.
}
}
9: When does entire lifetime of an activity happen?
Answer:
It happens between the call to onCreate() and the call to onDestroy().
10: When does visible lifetime of an activity happen?
Answer:
It happens between the call to onStart() and the call to onStop().
11: When does foreground lifetime of an activity happen?
Answer:
It happens between the call to onResume() and the call to onPause().
12: What is a Fragment?
Answer:
The fragment can be best explained as a behavior or a portion of user interface in an Activity.
13: Give an example of a fragment.
Answer:
Example is as under:
public static class ExampleFragment extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.example_fragment, container, false);
}
}
14: How to add a fragment to an activity?
Answer:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment android:name="com.example.news.ArticleListFragment"
android:id="@+id/list"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent" />
<fragment android:name="com.example.news.ArticleReaderFragment"
android:id="@+id/viewer"
android:layout_weight="2"
android:layout_width="0dp"
android:layout_height="match_parent" />
</LinearLayout>
15: How one can acquire an instance of FragmentTransaction from the FragmentManager?
Answer:
An example to acquire an instance of FragmentTransaction is given below:
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
16: How to create new fragment and transaction?
Answer:
Do the following:
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
17: How to add a transaction to the back stack?
Answer:
The following code snippet shows how to add a transaction to the back stack: