java/com/android/incallui/TransactionSafeFragmentActivity.java

/*
 * Copyright (C) 2011 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.incallui;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;

/**
 * A common superclass that keeps track of whether an {@link Activity} has saved its state yet or
 * not.
 */
public abstract class TransactionSafeFragmentActivity extends FragmentActivity {

  private boolean isSafeToCommitTransactions;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    isSafeToCommitTransactions = true;
  }

  @Override
  protected void onStart() {
    super.onStart();
    isSafeToCommitTransactions = true;
  }

  @Override
  protected void onResume() {
    super.onResume();
    isSafeToCommitTransactions = true;
  }

  @Override
  protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    isSafeToCommitTransactions = false;
  }

  /**
   * Returns true if it is safe to commit {@link FragmentTransaction}s at this time, based on
   * whether {@link Activity#onSaveInstanceState} has been called or not.
   *
   * <p>Make sure that the current activity calls into {@link super.onSaveInstanceState(Bundle
   * outState)} (if that method is overridden), so the flag is properly set.
   */
  public boolean isSafeToCommitTransactions() {
    return isSafeToCommitTransactions;
  }
}