Collections
Java provides the Collections utility class for common operations.
Collections.sort(list);
Collections.reverse(list);
Collections.max(list);
Collections.min(list);
Collections.frequency(list, value);Arrays
For arrays, use Arrays:
Arrays.sort(arr);
Arrays.binarySearch(arr, target);
Arrays.fill(dp, -1);For immutable or fixed-size collections:
Arrays.asList()returns a fixed-size list backed by the array.List.of()returns an unmodifiable list.
List<Integer> fixed = Arrays.asList(1, 2, 3);
List<Integer> immutable = List.of(1, 2, 3);StringBuilder
Efficient string construction
StringBuilder sb = new StringBuilder();
sb.append("hello");
sb.reverse();