android.support.v4.app.BackstackAccessor.java Source code

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Here is the source code for android.support.v4.app.BackstackAccessor.java

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/*
 * Copyright 2016 Hannes Dorfmann.
 *
 * 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 android.support.v4.app;

/**
 * With this utility class one can access the fragment backstack
 *
 * @author Hannes Dorfmann
 */
public class BackstackAccessor {

    private BackstackAccessor() {
        throw new IllegalStateException("Not instantiatable");
    }

    /**
     * Checks whether or not a given fragment is on the backstack of the fragment manager (could also
     * be on top of the backstack and hence visible)
     *
     * @param fragment The fragment you want to check if its on the back stack
     * @return true, if the given Fragment is on the back stack, otherwise false (not on the back
     * stack)
     */
    public static boolean isFragmentOnBackStack(Fragment fragment) {
        return fragment.isInBackStack();
    }
    /*
      public static boolean isFragmentOnBackStack(Fragment fragment) {
        
        FragmentManager fragmentManager = fragment.getFragmentManager();
        int backStackSize = fragmentManager.getBackStackEntryCount();
        for (int i = 0; i < backStackSize; i++) {
          BackStackRecord stackEntry = (BackStackRecord) fragmentManager.getBackStackEntryAt(i);
          int opsCount = stackEntry.mOps == null ? 0 : stackEntry.mOps.size();
          if (opsCount > 0) {
    BackStackRecord.Op op = stackEntry.mOps.get(opsCount-1);
    if (op.fragment == fragment) {
      return true;
    }
          }
        }
        
        return false;
      }
    */

    /*
      private static boolean findNext(@NonNull Fragment toFind, @Nullable BackStackRecord.Op next) {
        if (next == null) {
          return false;
        }
        
        if (toFind == next.fragment) {
          return true;
        } else {
          return findNext(toFind, next.next);
        }
      }
        
      private static boolean findPrevious(@NonNull Fragment toFind,
          @Nullable BackStackRecord.Op previous) {
        if (previous == null) {
          return false;
        }
        
        if (toFind == previous.fragment) {
          return true;
        } else {
          return findPrevious(toFind, previous.prev);
        }
      }
      */
}