added array manipulation snippets

snippets/java/array-manipulation/remove-duplicates.md

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+---
+title: Remove duplicates
+description: Removes duplicate elements from an list
+author: Mcbencrafter
+tags: list,duplicates,unique
+---
+
+```java
+import java.util.List;
+import java.util.stream.Collectors;
+
+public static <T> List<T> removeDuplicates(List<T> list) {
+    return list.stream()
+        .distinct()
+        .collect(Collectors.toList());
+}
+
+// Usage:
+List<Integer> list = List.of(1, 2, 3, 4, 5, 1, 2, 3, 4, 5);
+List<Integer> result = removeDuplicates(list);
+System.out.println("List with duplicates removed: " + result); // [1, 2, 3, 4, 5]
+```

snippets/java/array-manipulation/reverse-list.md

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+---
+title: Reverse list
+description: Reverses the contents of an list
+author: Mcbencrafter
+tags: list,reverse
+---
+
+```java
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public static <T> List<T> reverseList(List<T> list) {
+    List<T> reversedList = new ArrayList<>(list);
+    Collections.reverse(reversedList);
+    return reversedList;
+}
+
+// Usage:
+List<Integer> list = List.of(1, 3, 5, 7, 5);
+List<Integer> result = reverseList(lst);
+System.out.println("List reversed: " + result); // [5, 7, 5, 3, 1]
+```

snippets/java/array-manipulation/sort-list.md

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+---
+title: Sort list
+description: Sorts the contents of an numeric list
+author: Mcbencrafter
+tags: list,sorting,numberic,order,ascending,descending
+---
+
+```java
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public static <T extends Number & Comparable<T>> List<T> sortNumericList(List<T> list, boolean ascending) {
+    return list.stream()
+        .sorted(ascending ? Comparator.naturalOrder() : Comparator.reverseOrder())
+        .collect(Collectors.toList());
+}
+
+// Usage:
+List<Integer> list = List.of(5, 3, 1, 4, 2);
+List<Integer> result = sortNumericList(list, true);
+System.out.println("List sorted in ascending order: " + result); // [1, 2, 3, 4, 5]
+result = sortNumericList(list, false);
+System.out.println("List sorted in descending order: " + result); // [5, 4, 3, 2, 1]
+```