使用函数接口确保参数，但推断更具体的返回类型

import java.util.Arrays;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class FunctionInterfaceExample {
    public static void main(String[] args) {
        List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David");

        // 使用Predicate过滤名字长度大于3的元素
        Predicate<String> lengthGreaterThanThree = s -> s.length() > 3;
        List<String> filteredNames = names.stream()
                                           .filter(lengthGreaterThanThree)
                                           .collect(Collectors.toList());
        System.out.println(filteredNames); // 输出: [Alice, Charlie, David]

        // 使用Function将名字转换为大写
        Function<String, String> toUpperCase = String::toUpperCase;
        List<String> uppercasedNames = names.stream()
                                             .map(toUpperCase)
                                             .collect(Collectors.toList());
        System.out.println(uppercasedNames); // 输出: [ALICE, BOB, CHARLIE, DAVID]

        // 使用Consumer打印每个名字
        Consumer<String> printName = System.out::println;
        names.forEach(printName);
    }
}

Function<Integer, String> intToString = (Integer i) -> String.valueOf(i);