AsyncTask sample (non-retain Fragment)

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button
        android:id="@+id/update"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="start updateText" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="" />

</LinearLayout>

MainActivity.java

package test.fragment.asynctask;

import test.fragment.R;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        Log.d(getClass().getName(), "[onCreate(activity)]");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        findViewById(R.id.update).setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                startUpdateText();
            }
        });
    }

    @Override
    protected void onDestroy() {
        Log.d(getClass().getName(), "[onDestroy(activity)]");
        super.onDestroy();
    }

    private void startUpdateText() {
        UpdateTextFragment fragment = UpdateTextFragment.newInstance();
        getFragmentManager().beginTransaction().add(fragment, "updateText").commit();
        fragment.startUpdateText();
    }
}

UpdateTextFragment.java

package test.fragment.asynctask;

import test.fragment.R;
import android.app.Activity;
import android.app.Fragment;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class UpdateTextFragment extends Fragment {

    public static UpdateTextFragment newInstance() {
        return new UpdateTextFragment();
    }

    private AsyncTask<Void, String, Void> task;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        Log.d(getClass().getName(), "[onCreate]");
        super.onCreate(savedInstanceState);

        // Activity再生成時に Activity#onCreate/onDestroy が走らないようにする
        setRetainInstance(true);
    }

    @Override
    public void onDestroy() {
        Log.d(getClass().getName(), "[onDestroy]");
        super.onDestroy();

        if (task != null) {
            task.cancel(true);
        }
    }

    /**
     * テキスト更新処理(非同期)
     */
    public void startUpdateText() {
        task = new UpdateAsyncTask();
        task.execute();
    }

    private class UpdateAsyncTask extends AsyncTask<Void, String, Void> {

        @Override
        protected Void doInBackground(Void... params) {
            while (!isCancelled()) {
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                }

                // テキスト更新
                publishProgress("time: " + System.currentTimeMillis());
            }
            return null;
        }

        @Override
        protected void onProgressUpdate(String... values) {
            updateTextView(values[0]);
        }

        private void updateTextView(String text) {
            final Activity activity = getActivity();
            if (activity == null) {
                return;
            }

            final TextView textView = ((TextView) activity.findViewById(R.id.text));
            if (textView == null) {
                return;
            }
            textView.setText(text);
        }
    }

    @Override
    public void onAttach(Activity activity) {
        Log.d(getClass().getName(), "[onAttach]");
        super.onAttach(activity);
    }

    @Override
    public void onDetach() {
        Log.d(getClass().getName(), "[onDetach]");
        super.onDetach();
    }
}