Lambda Sample Examples

✅ 1. Lambda with No Parameters

Runnable greet = () -> System.out.println("Hello from Lambda!");
greet.run();

✅ 2. Lambda with One Parameter

Consumer<String> printer = name -> System.out.println("Welcome, " + name);
printer.accept("Aftab");

✅ 3. Lambda with Two Parameters (Add Two Numbers)

BiFunction<Integer, Integer, Integer> add = (a, b) -> a + b;
System.out.println(add.apply(5, 3)); // Output: 8

✅ 4. Sorting a List with Lambda

List<String> names = Arrays.asList("Ravi", "Aftab", "Neha");

names.sort((s1, s2) -> s1.compareToIgnoreCase(s2));
System.out.println(names); // [Aftab, Neha, Ravi]

✅ 5. Lambda with Custom Functional Interface

@FunctionalInterface
interface MathOperation {
    int operate(int a, int b);
}

MathOperation multiply = (a, b) -> a * b;
System.out.println(multiply.operate(4, 5)); // Output: 20

✅ 6. Filtering a List Using Predicate + Lambda

List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

numbers.stream()
       .filter(n -> n % 2 == 0)
       .forEach(System.out::println); // Output: 2, 4

✅ 7. Using Lambda in Threads

new Thread(() -> System.out.println("Running in a thread")).start();

✅ 8. Mapping List to Uppercase Using Lambda

List<String> cities = Arrays.asList("delhi", "mumbai", "noida");

List<String> upperCities = cities.stream()
                                 .map(city -> city.toUpperCase())
                                 .collect(Collectors.toList());

System.out.println(upperCities); // [DELHI, MUMBAI, NOIDA]

✅ 9. Lambda with Optional

Optional<String> name = Optional.of("Neha");

name.ifPresent(n -> System.out.println("Hello " + n)); // Output: Hello Neha

✅ 10. Lambda to Count Words Longer Than 3 Letters

List<String> words = Arrays.asList("Hi", "Java", "Lambda", "Fun");

long count = words.stream()
                  .filter(w -> w.length() > 3)
                  .count();

System.out.println("Count: " + count); // Output: 2

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