java中的->代表什么含义 箭头运算符->在Java中如何使用看完这篇就懂了

// 传统写法
Runnable runnable = new Runnable() {
    @Override
    public void run() {
        System.out.println("Hello from Runnable!");
    }
};

// 使用lambda表达式
Runnable runnableLambda = () -> System.out.println("Hello from Runnable using lambda!");

runnable.run();
runnableLambda.run();

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class StreamExample {
    public static void main(String[] args) {
        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

        // 使用lambda表达式过滤偶数并求平方
        List<Integer> evenSquares = numbers.stream()
                .filter(n -> n % 2 == 0) // 过滤偶数
                .map(n -> n * n)         // 求平方
                .collect(Collectors.toList()); // 收集结果

        System.out.println("Even Squares: " + evenSquares);
    }
}

import java.util.Arrays;
import java.util.List;
import java.util.function.Predicate;

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

        // 使用类型推断
        Predicate<String> startsWithA = s -> s.startsWith("A");

        // 显式声明类型
        Predicate<String> startsWithB = (String s) -> s.startsWith("B");

        names.stream()
                .filter(startsWithA)
                .forEach(System.out::println); // 输出 Alice

        names.stream()
                .filter(startsWithB)
                .forEach(System.out::println); // 没有输出
    }
}

public class VariableCaptureExample {
    public static void main(String[] args) {
        int number = 10; // effectively final

        Runnable runnable = () -> {
            System.out.println("The number is: " + number);
        };

        runnable.run();
    }
}

public class VariableCaptureExample {
    public static void main(String[] args) {
        int number = 10;

        // 编译错误：Variable used in lambda expression should be final or effectively final
        // Runnable runnable = () -> {
        //     number = number + 5;
        //     System.out.println("The number is: " + number);
        // };

        // runnable.run();
    }
}

import java.util.Arrays;
import java.util.List;

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

        // 使用方法引用
        names.forEach(System.out::println);

        // 等价的lambda表达式
        names.forEach(name -> System.out.println(name));
    }
}