src/com/android/mail/browse/ConfirmDialogFragment.java

/*******************************************************************************
 *      Copyright (C) 2012 Google Inc.
 *      Licensed to The Android Open Source Project.
 *
 *      Licensed under the Apache License, Version 2.0 (the "License");
 *      you may not use this file except in compliance with the License.
 *      You may obtain a copy of the License at
 *
 *           http://www.apache.org/licenses/LICENSE-2.0
 *
 *      Unless required by applicable law or agreed to in writing, software
 *      distributed under the License is distributed on an "AS IS" BASIS,
 *      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *      See the License for the specific language governing permissions and
 *      limitations under the License.
 *******************************************************************************/

package com.android.mail.browse;

import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.FragmentManager;
import android.content.DialogInterface;
import android.os.Bundle;

import com.android.mail.R;
import com.android.mail.ui.ControllableActivity;
import com.android.mail.ui.ConversationUpdater;

/**
 * A dialog which is also a fragment. This dialog shows a message, two buttons (ok/cancel), and runs
 * a listener only for the positive action (ok). Since this is a fragment, it is created
 * automatically over orientation changes. To make a listener that works with this dialog, create a
 * listener with {@link ConversationUpdater#makeDialogListener(int, boolean)}, which correctly
 * handles activity life-cycle events.
 */
public class ConfirmDialogFragment extends DialogFragment {
    /** Tag for saving the message shown in the dialog. */
    private static final String MESSAGE_KEY = "message";
    /** Tag for the dialog in the fragment manager. */
    private static final String DIALOG_TAG = "confirm-dialog";

    /**
     * Since the fragment can be easily destroyed, get the listener from the central activity
     * immediately after the positive button ("OK" in English) is clicked.  We cannot get the
     * listener in {@link #onActivityCreated(Bundle)} because the controller has not had a chance
     * to create the listener yet.
     */
    private final AlertDialog.OnClickListener POSITIVE_ACTION = new AlertDialog.OnClickListener() {
        @Override
        public void onClick(DialogInterface arg0, int arg1) {
            // Casting to ControllableActivity will crash if it fails. This is the expected
            // behavior, since the cast should always succeed. Cast failures only occur during
            // development.
            final AlertDialog.OnClickListener listener =
                    ((ControllableActivity) getActivity()).getConversationUpdater().getListener();
            if (listener != null) {
                listener.onClick(arg0, arg1);
            }
        }
    };

    /**
     * Needs a public empty constructor for instantiation on orientation changes.
     */
    public ConfirmDialogFragment() {}

    /**
     * Create a new {@link ConfirmDialogFragment}.
     * @param message
     * @return new {@link ConfirmDialogFragment} object.
     */
    public static ConfirmDialogFragment newInstance(CharSequence message) {
        final ConfirmDialogFragment f = new ConfirmDialogFragment();
        final Bundle args = new Bundle();
        args.putCharSequence(MESSAGE_KEY, message);
        f.setArguments(args);
        return f;
    }

    @Override
    public Dialog onCreateDialog(Bundle savedState) {
        final AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        final CharSequence message = (getArguments()).getCharSequence(MESSAGE_KEY);
        builder.setMessage(message)
               .setPositiveButton(R.string.ok, POSITIVE_ACTION)
               .setNegativeButton(R.string.cancel, null);
        return builder.create();
    }

    /**
     * Display this dialog with the provided fragment manager
     * @param manager
     */
    public final void displayDialog (FragmentManager manager) {
        show(manager, DIALOG_TAG);
    }
}