Throw exception if assigning value of wrong type

1 files changed, 14 insertions, 0 deletions

diff --git a/src/main/java/org/zwobble/couscous/util/CousCousMaps.java b/src/main/java/org/zwobble/couscous/util/CousCousMaps.java
new file mode 100644
index 0000000..5fb4dca
--- /dev/null
+++ b/src/main/java/org/zwobble/couscous/util/CousCousMaps.java
@@ -0,0 +1,14 @@
+package org.zwobble.couscous.util;
+
+import java.util.Map;
+import java.util.function.Function;
+
+import static java.util.stream.Collectors.toMap;
+
+public class CousCousMaps {
+    public static <K1, K2, V> Map<K2, V> mapKeys(Map<K1, V> map, Function<K1, K2> func) {
+        return map.entrySet()
+            .stream()
+            .collect(toMap(entry -> func.apply(entry.getKey()), entry -> entry.getValue()));
+    }
+}