Android Developer Interview

Suppose you have a v-shape array, e.g [1, 12, 31, 44, 51, 54, 23, 22, 10]. How to find the maximum value in a v-shape array?

假如我们有一个v-shape数组，如[1, 12, 31, 44, 51, 54, 23, 22, 10]。怎样找出它的最大值？

• Describe three common use cases for using an Intent.

• Under what condition could the code sample below crash your application? How would you modify the code to avoid this potential problem? Explain your answer.

Intent sendIntent = new Intent();
sendIntent.setAction(Intent.ACTION_SEND);
sendIntent.putExtra(Intent.EXTRA_TEXT, textMessage);
sendIntent.setType(HTTP.PLAIN_TEXT_TYPE); // "text/plain" MIME type
startActivity(sendIntent);

• What is the relationship between the life cycle of an AsyncTask and an Activity? What problems can this result in? How can these problems be avoided?

• What is difference between Serializable and Parcelable ? Which is best approach in Android ?

public class MainActivity extends Activity implements OnClickListener {
 
  final String TAG = "States";
 
  Button btnActTwo;
 
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
 
    btnActTwo = (Button) findViewById(R.id.btnActTwo);
    btnActTwo.setOnClickListener(this);
 
    Log.d(TAG, "MainActivity: onCreate()");
  }
 
  @Override
  protected void onRestart() {
    super.onRestart();
    Log.d(TAG, "MainActivity: onRestart()");
  }
 
  @Override
  protected void onStart() {
    super.onStart();
    Log.d(TAG, "MainActivity: onStart()");
  }
 
  @Override
  protected void onResume() {
    super.onResume();
    Log.d(TAG, "MainActivity: onResume()");
  }
 
  @Override
  protected void onPause() {
    super.onPause();
    Log.d(TAG, "MainActivity: onPause()");
  }
 
  @Override
  protected void onStop() {
    super.onStop();
    Log.d(TAG, "MainActivity: onStop()");
  }
 
  @Override
  protected void onDestroy() {
    super.onDestroy();
    Log.d(TAG, "MainActivity: onDestroy()");
  }
 
  @Override
  public void onClick(View v) {
    Intent intent = new Intent(this, ActivityTwo.class);
    startActivity(intent);
  }
}

public class ActivityTwo extends Activity {
 
  final String TAG = "States";
 
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.two);
    Log.d(TAG, "ActivityTwo: onCreate()");
  }
 
  @Override
  protected void onRestart() {
    super.onRestart();
    Log.d(TAG, "ActivityTwo: onRestart()");
  }
 
  @Override
  protected void onStart() {
    super.onStart();
    Log.d(TAG, "ActivityTwo: onStart()");
  }
 
  @Override
  protected void onResume() {
    super.onResume();
    Log.d(TAG, "ActivityTwo: onResume()");
  }
 
  @Override
  protected void onPause() {
    super.onPause();
    Log.d(TAG, "ActivityTwo: onPause()");
  }
 
  @Override
  protected void onStop() {
    super.onStop();
    Log.d(TAG, "ActivityTwo: onStop()");
  }
 
  @Override
  protected void onDestroy() {
    super.onDestroy();
    Log.d(TAG, "ActivityTwo: onDestroy()");
  }
}

public class ActivityThree extends Activity {
 
  final String TAG = "States";
 
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.three);
    Log.d(TAG, "ActivityThree: onCreate()");
    this.finish();
  }
 
  @Override
  protected void onRestart() {
    super.onRestart();
    Log.d(TAG, "ActivityThree: onRestart()");
  }
 
  @Override
  protected void onStart() {
    super.onStart();
    Log.d(TAG, "ActivityThree: onStart()");
  }
 
  @Override
  protected void onResume() {
    super.onResume();
    Log.d(TAG, "ActivityThree: onResume()");
  }
 
  @Override
  protected void onPause() {
    super.onPause();
    Log.d(TAG, "ActivityThree: onPause()");
  }
 
  @Override
  protected void onStop() {
    super.onStop();
    Log.d(TAG, "ActivityThree: onStop()");
  }
 
  @Override
  protected void onDestroy() {
    super.onDestroy();
    Log.d(TAG, "ActivityThree: onDestroy()");
  }
}

• Write down the log results at 4 different cases
  • Start MainActivity
  • Invoke onClick() at MainActivity
  • User press back button from ActivityTwo
  • Start ActivityThree