Android Fragment

Android Fragment

BaseFragmentActivity.java

import android.app.Activity;
import android.app.FragmentTransaction;
import android.os.Bundle;

import java.util.LinkedList;

public class BaseFragmentActivity extends Activity {

	private LinkedList<FragmentTransaction> mFragmentTransactions;
	private boolean mIsTransactionAllowed;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		mFragmentTransactions = new LinkedList<>();
	}

	@Override
	protected void onStop() {
		disableFragmentTransaction();
		super.onStop();
	}

	@Override
	protected void onSaveInstanceState(Bundle outState) {
		disableFragmentTransaction();
		super.onSaveInstanceState(outState);
	}

	@Override
	protected void onDestroy() {
		clearFragmentTransaction();
		super.onDestroy();
	}

	@Override
	protected void onPostResume() {
		super.onPostResume();
		allowFragmentTransaction();
		commitPendingFragmentTransactions();
	}

	private void disableFragmentTransaction() {
		mIsTransactionAllowed = false;
	}

	private void clearFragmentTransaction() {
		mFragmentTransactions.clear();
	}

	private void allowFragmentTransaction() {
		mIsTransactionAllowed = true;
	}

	private void commitPendingFragmentTransactions() {
		while (!mFragmentTransactions.isEmpty()) {
			FragmentTransaction fragmentTransaction = mFragmentTransactions.removeFirst();
			fragmentTransaction.commit();
		}
	}

	protected boolean commit(FragmentTransaction fragmentTransaction) {
		if (mIsTransactionAllowed) {
			fragmentTransaction.commit();
		} else {
			mFragmentTransactions.addLast(fragmentTransaction);
		}
		return true;
	}
}

LoadingFragment.java

// Fragment

public class LoadingFragment extends Fragment {

	private TaskCallbacks mTaskCallbacks;
	private MyTask mTask;

	public interface TaskCallbacks {
		void onProgressUpdate(int percent);
	}

	public static LoadingFragment newInstance() {
		LoadingFragment fragment = new LoadingFragment();
		return fragment;
	}

	@Override
	public void onAttach(Activity activity) {
		super.onAttach(activity);
		if (!(activity instanceof TaskCallbacks)) {
			throw new IllegalArgumentException("Activity must implement TaskCallbacks");
		}
		mTaskCallbacks = (TaskCallbacks) activity;
	}

	@Override
	public void onDetach() {
		super.onDetach();
		mTaskCallbacks = null;
	}

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setRetainInstance(true);
		mTask = new MyTask();
		mTask.execute();
	}
	
	public void cancel() {
		if(mTask != null) {
			mTask.cancel(true);
		}
	}

	private class MyTask extends AsyncTask<Void, Integer, Void> {

		@Override
		protected Void doInBackground(Void... params) {
			for (int i = 0; i <= 100 && !isCancelled(); i++) {
				SystemClock.sleep(100);
				publishProgress(i);
			}

			return null;
		}

		@Override
		protected void onProgressUpdate(Integer... values) {
			if (mTaskCallbacks != null) {
				mTaskCallbacks.onProgressUpdate(values[0]);
			}
		}
	}
}


// Activity

public class MyActivity extends Activity implements LoadingFragment.TaskCallbacks{

	private LoadingFragment mTaskFragment;

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

		L.LOG_TAG = "fragment lifecycle";

		FragmentManager fm = getFragmentManager();
		mTaskFragment = (LoadingFragment) fm.findFragmentByTag("task");

		// If the Fragment is non-null, then it is currently being
		// retained across a configuration change.
		if (mTaskFragment == null) {
			mTaskFragment = LoadingFragment.newInstance();
			fm.beginTransaction().add(mTaskFragment, "task").commit();
		}
	}

	@Override
	protected void onDestroy() {
		super.onDestroy();
		if (mTaskFragment != null) {
			mTaskFragment.cancel();
		}
	}

	@Override
	public void onProgressUpdate(int percent) {
		L.d("onProgressUpdate " + percent);
	}

}