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import java.util.*; import java.util.stream.Collectors; public class CollectionsDemo { public static void main(String[] args) { // ArrayList - ordered, allows duplicates List<String> fruits = new ArrayList<>(Arrays.asList("Apple", "Banana", "Cherry")); fruits.add("Date"); fruits.remove("Banana"); System.out.println(fruits); // HashMap - key-value pairs Map<String, Integer> scores = new HashMap<>(); scores.put("Alice", 95); scores.put("Bob", 87); scores.put("Charlie", 92); for (Map.Entry<String, Integer> entry : scores.entrySet()) { System.out.println(entry.getKey() + ": " + entry.getValue()); } // Stream API List<String> filtered = fruits.stream() .filter(f -> f.startsWith("A")) .map(String::toUpperCase) .sorted() .collect(Collectors.toList()); System.out.println(filtered); } }
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