Java 9 - 改进 Optional 类

package com.lfsun.java9study.optional;

import java.util.Optional;

public class OptionalImprovementsExample {
    
    

    public static void main(String[] args) {
    
    
        // 示例1：ifPresentOrElse 方法
        Optional<String> optionalValue = Optional.of("Hello, World!");

        optionalValue.ifPresentOrElse(
                value -> System.out.println("Value is present: " + value),
                () -> System.out.println("Value is empty.")
        );

        // 示例2：stream 方法
        Optional<String> optionalValue2 = Optional.of("Hello, World!");

        optionalValue2.stream()
                .map(value -> value + " Stream")
                .forEach(System.out::println);

        // 示例3：or 方法
        Optional<String> optionalValue3 = Optional.empty();
        Optional<String> backupValue = Optional.of("Backup Value");

        Optional<String> result = optionalValue3.or(() -> backupValue);
        System.out.println(result); // 输出：Optional[Backup Value]
    }
}