小编dba*_*tor的帖子

我试图在本文后面的Java 8中实现Monad接口但是我有以下编译错误

找到2个错误:

• File:FunctorsMonads.java [line:36]

  错误:FOptional不是抽象的,并且不会覆盖Monad中的抽象方法flatMap(java.util.function.Function>)

• File:FunctorsMonads.java [line:50]

  错误:名称冲突:FOptional中的flatMap(java.util.function.Function>)和Monad中的flatMap(java.util.function.Function)具有相同的擦除,但都没有覆盖其他

该Functor接口工作得很好.任何帮助深表感谢.

这是代码:

import java.util.function.Function;

public class FunctorsMonads {

  public static void main(String[] args) {
    System.out.println(tryParse("47"));
    System.out.println(tryParse("a"));

    FOptional<String> str = FOptional.of("47");
    System.out.println(str);
    FOptional<FOptional<Integer>> num = str.map(FunctorsMonads::tryParse);
    System.out.println(num);
    FOptional<Integer> num2 = str.flatMap(FunctorsMonads::tryParse);
    System.out.println(num2);
  }

  static FOptional<Integer> tryParse(String s){
    try {
      final int i = Integer.parseInt(s);
      return FOptional.of(i);
    } catch (NumberFormatException e) {
      return FOptional.empty();
    }
  }
}

interface Functor<T, F extends Functor<?, ?>> {
  <R> F map(Function<T, R> f); …

我正在使用 Spring Boot 3.1.5、 Java21和 maven 3.9.5。我运行时出现以下错误mvn spring-boot:build-image

[INFO]  > Pulling builder image 'docker.io/paketobuildpacks/builder:base' 100%
[INFO]  > Pulled builder image 'paketobuildpacks/builder@sha256:17ea21162ba8c7717d3ead3ee3836a368aced7f02f2e59658e52029bd6d149e7'
[INFO]  > Pulling run image 'docker.io/paketobuildpacks/run:base-cnb' 100%
[INFO]  > Pulled run image 'paketobuildpacks/run@sha256:1af9935d8987fd52b2266d288200c9482d1dd5529860bbf5bc2d248de1cb1a38'
[INFO]  > Executing lifecycle version v0.16.5
[INFO]  > Using build cache volume 'pack-cache-8847f704ad41.build'
[INFO] 
[INFO]  > Running creator
[INFO]     [creator]     ===> ANALYZING
[INFO]     [creator]     Image with name "docker.io/library/elevate-insights:0.0.1-SNAPSHOT" not found
[INFO]     [creator]     ===> DETECTING
[INFO]     [creator]     6 of 26 buildpacks participating …