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Diffstat (limited to 'java/com/android/dialer/common/FragmentUtils.java')
-rw-r--r-- | java/com/android/dialer/common/FragmentUtils.java | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/java/com/android/dialer/common/FragmentUtils.java b/java/com/android/dialer/common/FragmentUtils.java new file mode 100644 index 000000000..cb036959d --- /dev/null +++ b/java/com/android/dialer/common/FragmentUtils.java @@ -0,0 +1,98 @@ +/* + * Copyright (C) 2016 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.dialer.common; + +import android.support.annotation.CheckResult; +import android.support.annotation.NonNull; +import android.support.annotation.Nullable; +import android.support.annotation.VisibleForTesting; +import android.support.v4.app.Fragment; +import android.support.v4.app.FragmentActivity; + +/** Utility methods for working with Fragments */ +public class FragmentUtils { + + private static Object parentForTesting; + + @VisibleForTesting(otherwise = VisibleForTesting.NONE) + public static void setParentForTesting(Object parentForTesting) { + FragmentUtils.parentForTesting = parentForTesting; + } + + /** + * @return The parent of frag that implements the callbackInterface or null if no such parent can + * be found + */ + @CheckResult(suggest = "#checkParent(Fragment, Class)}") + @Nullable + public static <T> T getParent(@NonNull Fragment fragment, @NonNull Class<T> callbackInterface) { + if (callbackInterface.isInstance(parentForTesting)) { + @SuppressWarnings("unchecked") // Casts are checked using runtime methods + T parent = (T) parentForTesting; + return parent; + } + + Fragment parentFragment = fragment.getParentFragment(); + if (callbackInterface.isInstance(parentFragment)) { + @SuppressWarnings("unchecked") // Casts are checked using runtime methods + T parent = (T) parentFragment; + return parent; + } else { + FragmentActivity activity = fragment.getActivity(); + if (callbackInterface.isInstance(activity)) { + @SuppressWarnings("unchecked") // Casts are checked using runtime methods + T parent = (T) activity; + return parent; + } + } + return null; + } + + /** Returns the parent or throws. Should perform check elsewhere(e.g. onAttach, newInstance). */ + @NonNull + public static <T> T getParentUnsafe( + @NonNull Fragment fragment, @NonNull Class<T> callbackInterface) { + return Assert.isNotNull(getParent(fragment, callbackInterface)); + } + + /** + * Ensures fragment has a parent that implements the corresponding interface + * + * @param frag The Fragment whose parents are to be checked + * @param callbackInterface The interface class that a parent should implement + * @throws IllegalStateException if no parents are found that implement callbackInterface + */ + public static void checkParent(@NonNull Fragment frag, @NonNull Class<?> callbackInterface) + throws IllegalStateException { + if (parentForTesting != null) { + return; + } + if (FragmentUtils.getParent(frag, callbackInterface) == null) { + String parent = + frag.getParentFragment() == null + ? frag.getActivity().getClass().getName() + : frag.getParentFragment().getClass().getName(); + throw new IllegalStateException( + frag.getClass().getName() + + " must be added to a parent" + + " that implements " + + callbackInterface.getName() + + ". Instead found " + + parent); + } + } +} |