Maps: Map that should be sorted on the basis of values and not keys.

rpanjrath · rpanjrath · commit 87d120cee151 · 2014-02-05T15:09:26.000-08:00
diff --git a/README.md b/README.md
@@ -117,6 +117,9 @@ Maps
 2.  Least Recently Used (LRU) cache implementation.
     Link: https://github.com/techpanja/interviewproblems/blob/master/src/maps/lrucache/LRUCache.java
 
+3.  Map that should be sorted on the basis of values and not keys. (Use of treemap and comparator.)
+    Link:
+
 Number-Problems
 ---------------
 1.  Concatenate two numbers. for e.g. 123, 0456 = 1230456
diff --git a/src/maps/sortofvaluesinmap/SortOnValuesInMap.java b/src/maps/sortofvaluesinmap/SortOnValuesInMap.java
@@ -0,0 +1,56 @@
+package maps.sortofvaluesinmap;
+
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * A map that should be sorted on the basis of values and not keys.
+ * Created by techpanja
+ * Created on 2/5/14 2:33 PM.
+ */
+public class SortOnValuesInMap {
+
+    private SortOnValuesInMap() {
+
+    }
+
+    public static Map<String, Integer> sortOnValuesInMap(Map<String, Integer> inputMap) {
+        ValueComparator valueComparator = new ValueComparator(inputMap);
+        Map<String, Integer> sortedMapOnValue = new TreeMap<>(valueComparator);
+        sortedMapOnValue.putAll(inputMap);
+        return sortedMapOnValue;
+    }
+
+    static class ValueComparator implements Comparator<String> {
+
+        private Map<String, Integer> inputMap;
+
+        public ValueComparator(Map<String, Integer> inputMap) {
+            this.inputMap = inputMap;
+        }
+
+        @Override
+        public int compare(String string1, String string2) {
+            if (inputMap.get(string1) > inputMap.get(string2)) {
+                return -1;
+            } else {
+                return 1;
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        Map<String, Integer> map = new HashMap<>();
+        map.put("A", 2);
+        map.put("B", 1);
+        map.put("C", 3);
+        map.put("D", 0);
+        map.put("E", 8);
+        Map<String, Integer> output = sortOnValuesInMap(map);
+        for (String temp : output.keySet()) {
+            System.out.println(temp);
+        }
+    }
+}
