ラムダ式 解答例

BinaryOperator sum = (a, b) -> a + b;
System.out.println(sum.apply(3, 5)); // 8

Function doubleFunc = x -> x * 2;
System.out.println(doubleFunc.apply(3)); // 6

Function oddOrEven = x -> x % 2 == 0 ? "偶数" : "奇数";
System.out.println(oddOrEven.apply(3)); // 奇数

Predicate isPositive = x -> x > 0;
System.out.println(isPositive.test(3)); // true

Consumer printString = str -> System.out.println(str);
printString.accept("Hello, world!"); // Hello, world!

Supplier randomNum = () -> new Random().nextInt(10) + 1;
System.out.println(randomNum.get()); // 例: 7

Comparator lengthComparator = (s1, s2) -> Integer.compare(s1.length(), s2.length());
List strings = Arrays.asList("apple", "banana", "pear", "orange");
Collections.sort(strings, lengthComparator);
System.out.println(strings); // [pear, apple, banana, orange]

Runnable printHello = () -> System.out.println("Hello, world!");
printHello.run(); // Hello, world!

Function reverseString = str -> new StringBuilder(str).reverse().toString();
System.out.println(reverseString.apply("hello")); // olleh