util: Add a keyed list class and a sorted variant

This is inspired by C#'s KeyedCollection. The sorted variant removes the
need for an observable SortedMap.

Signed-off-by: Samuel Holland <samuel@sholland.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/app/src/main/java/com/wireguard/android/util/Keyed.java b/app/src/main/java/com/wireguard/android/util/Keyed.java
new file mode 100644
index 00000000..d79fdb97
--- /dev/null
+++ b/app/src/main/java/com/wireguard/android/util/Keyed.java
@@ -0,0 +1,9 @@
+package com.wireguard.android.util;
+
+/**
+ * Interface for objects that have a identifying key of the given type.
+ */
+
+public interface Keyed<K> {
+    K getKey();
+}