feat: Add Comparator Example

JavaDsaWithTest/src/main/java/org/practice/dsa/collections/ComparatorExample.java

@@ -0,0 +1,27 @@
+package org.practice.dsa.collections;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+public class ComparatorExample {
+    public static void main(String[] args) {
+        List<ComparableDemo> demo = new ArrayList<>();
+        demo.add(new ComparableDemo(3, "V"));
+        demo.add(new ComparableDemo(1, "B"));
+        demo.add(new ComparableDemo(2, "X"));
+
+//        Collections.sort(demo, new Comparator<ComparableDemo>() {
+//            @Override
+//            public int compare(ComparableDemo o1, ComparableDemo o2) {
+//                return o1.getName().compareTo(o2.getName());
+//            }
+//        });
+        // short form
+        Collections.sort(demo, Comparator.comparing(ComparableDemo::getName));
+
+        System.out.println("Sort by names:");
+        demo.forEach(System.out::println);
+    }
+}