public class PracticalTest01MainActivity extends Activity {

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

    if (savedInstanceState != null) {
      if (savedInstanceState.containsKey("leftCount")) {
        leftEditText.setText(savedInstanceState.getString("leftCount"));
      } else {
        leftEditText.setText(String.valueOf(0));
      }
      if (savedInstanceState.containsKey("rightCount")) {
        rightEditText.setText(savedInstanceState.getString("rightCount"));
      } else {
        rightEditText.setText(String.valueOf(0));
      }
    } else {
      leftEditText.setText(String.valueOf(0));
      rightEditText.setText(String.valueOf(0));
    }
  }

  @Override
  protected void onSaveInstanceState(Bundle savedInstanceState) {
    savedInstanceState.putString("leftCount", leftEditText.getText().toString());
    savedInstanceState.putString("rightCount", rightEditText.getText().toString());
  }
  
  @Override
  protected void onRestoreInstanceState(Bundle savedInstanceState) {
    if (savedInstanceState.containsKey("leftCount")) {
      leftEditText.setText(savedInstanceState.getString("leftCount"));
    } else {
      leftEditText.setText(String.valueOf(0));
    }
    if (savedInstanceState.containsKey("rightCount")) {
      rightEditText.setText(savedInstanceState.getString("rightCount"));
    } else {
      rightEditText.setText(String.valueOf(0));
    }
  }
  
  // ...
}