Source Code for BAEL-2534 : Determine if all elements are the same in a Java list

core-java-collections-list/src/main/java/com/baeldung/allequalelements/VerifyAllEqualListElements.java

@@ -1,5 +1,7 @@
 package com.baeldung.allequalelements;
 
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import org.apache.commons.collections4.IterableUtils;
 import com.google.common.base.Predicate;
@@ -9,21 +11,32 @@ public class VerifyAllEqualListElements {
 
     public boolean verifyAllEqualUsingALoop(List<String> list) {
         for (String s : list) {
-            if(!s.equals(list.get(0)))
+            if (!s.equals(list.get(0)))
                 return false;
         }
         return true;
     }
 
+    public boolean verifyAllEqualUsingHashSet(List<String> list) {
+        return new HashSet<String>(list).size() <= 1;
+    }
+
+    public boolean verifyAllEqualUsingFrequency(List<String> list) {
+        return list.isEmpty() || Collections.frequency(list, list.get(0)) == list.size();
+    }
+
     public boolean verifyAllEqualUsingStream(List<String> list) {
-          return list.stream().distinct().limit(2).count() <= 1;
+        return list.stream()
+            .distinct()
+            .limit(2)
+            .count() <= 1;
     }
 
     public boolean verifyAllEqualAnotherUsingStream(List<String> list) {
-        return list.isEmpty() || list.stream().allMatch(list.get(0)::equals);
+        return list.isEmpty() || list.stream()
+            .allMatch(list.get(0)::equals);
     }
 
-
     public boolean verifyAllEqualUsingGuava(List<String> list) {
         return Iterables.all(list, new Predicate<String>() {
             public boolean apply(String s) {