HashMap sort TreeMap

core-java-collections/src/main/java/com/baeldung/performance/Employee.java

@@ -44,4 +44,12 @@ public class Employee {
         result = 31 * result + name.hashCode();
         return result;
     }
+
+    @Override
+    public String toString() {
+        return "Employee{" +
+                "id=" + id +
+                ", name='" + name + '\'' +
+                '}';
+    }
 }

core-java-collections/src/main/java/com/baeldung/sort/SortHashMap.java

@@ -0,0 +1,42 @@
+package com.baeldung.sort;
+
+import com.baeldung.performance.Employee;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class SortHashMap {
+
+    private static Map<String, Employee> map = new HashMap<>();
+
+    public static void main(String[] args) {
+
+        initialize();
+
+        treeMapSortByKey();
+    }
+
+    public static void treeMapSortByKey()
+    {
+        TreeMap<String, Employee> sorted = new TreeMap<>(map);
+        sorted.putAll(map);
+
+        for (Map.Entry<String, Employee> entry : sorted.entrySet()) {
+            System.out.println("Key = " + entry.getKey() +
+                    ", Value = " + entry.getValue());
+        }
+
+    }
+
+    private static void initialize() {
+        Employee employee1 = new Employee(1L, "Mher");
+        map.put(employee1.getName(), employee1);
+        Employee employee2 = new Employee(22L, "Annie");
+        map.put(employee2.getName(), employee2);
+        Employee employee3 = new Employee(8L, "John");
+        map.put(employee3.getName(), employee3);
+        Employee employee4 = new Employee(2L, "George");
+        map.put(employee4.getName(), employee4);
+    }
+}