util: Extract non-Android utility interfaces

As part of a refactoring that will likely introduce more custom
collection classes, move the non-Android-specific parts outside the
com.wireguard.android package.

1 files changed, 28 insertions, 0 deletions

diff --git a/app/src/main/java/com/wireguard/util/KeyedList.java b/app/src/main/java/com/wireguard/util/KeyedList.java
new file mode 100644
index 00000000..1478dc19
--- /dev/null
+++ b/app/src/main/java/com/wireguard/util/KeyedList.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright © 2018 Samuel Holland <samuel@sholland.org>
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+package com.wireguard.util;
+
+import java.util.Collection;
+import java.util.List;
+
+/**
+ * A list containing elements that can be looked up by key. A {@code KeyedList} cannot contain
+ * {@code null} elements.
+ */
+
+public interface KeyedList<K, E extends Keyed<? extends K>> extends List<E> {
+    boolean containsAllKeys(Collection<K> keys);
+
+    boolean containsKey(K key);
+
+    E get(K key);
+
+    E getLast(K key);
+
+    int indexOfKey(K key);
+
+    int lastIndexOfKey(K key);
+}