I am facing a peculiar issue which I am not able to resolve. Not sure where I am going wrong.

Description – I have a JavaFX GUI. On GUI I have 2 input fields which accepts port number (string).
I have a java code which gets the data from the bean and creates yaml file with the configuration.

Code –

import org.springframework.stereotype.Service;
import org.yaml.snakeyaml.DumperOptions;
import org.yaml.snakeyaml.Yaml;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.time.LocalDateTime;
import java.util.LinkedHashMap;
import java.util.Map;

@Service
public class GenerateYamlFileImpl implements GenerateYamlFile {

    private static final Logger logger = LogManager.getLogger(GenerateYamlFileImpl.class);

    public void writeYamlfile(Container container, File file) {
        try (FileWriter writer = new FileWriter(file.getPath() + LocalDateTime.now() + FXMLPageConstants.FILE_TYPE)) {
            DumperOptions options = new DumperOptions();
            options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
            options.setPrettyFlow(true);
            Yaml yaml = new Yaml(options);
            Map<String, Object> data = new LinkedHashMap<>();
            data.put("name", container.getName());

            Map<String, Object> topology = new LinkedHashMap<>();
            Map<String, Object> nodes = new LinkedHashMap<>();
            for (Map.Entry<String, NodesProperties> entry : container.getTopology().getNodes().entrySet()) {
                Map<String, Object> nodeDetails = new LinkedHashMap<String, Object>();
                NodesProperties nodeProps = entry.getValue();
                nodeDetails.put("kind", nodeProps.getKind());
                nodeDetails.put("image", nodeProps.getImage());
                if (nodeProps.getGroup() != null && !nodeProps.getGroup().isBlank()) {
                    nodeDetails.put("group", nodeProps.getGroup());
                }
                if (nodeProps.getStartupConfig() != null && !nodeProps.getStartupConfig().isBlank()) {
                    nodeDetails.put("startup-config", nodeProps.getStartupConfig());
                }
                if (nodeProps.getPorts() != null && !nodeProps.getPorts().isEmpty()) {
                    String[] ports = nodeProps.getPorts().stream().map(port -> port+":"+"22").toArray(String[]::new);
                    nodeDetails.put("ports", ports);
                }
                nodes.put(entry.getKey(), nodeDetails);
            }
            topology.put("nodes", nodes);
            StringBuilder linksYaml = new StringBuilder();
            linksYaml.append("  links:n");
            for (Link link : container.getTopology().getLinks()) {
                linksYaml.append("    - endpoints: ["");
                linksYaml.append(String.join("", "", link.getEndpoints()));
                linksYaml.append(""]n");
            }
            topology.put("nodes", nodes);
            data.put("topology", topology);
            yaml.dump(data, writer);
            writer.write(linksYaml.toString());
            writer.flush();
            logger.info("YAML file generated successfully: ");
        } catch (IOException e) {
            logger.error("Error while writing YAML file", e);
        }
    }
}

public class Container {

    private String name;
    private Topology topology;

}

public class Topology {

    private Map<String, NodesProperties> nodes;
    private List<Link> links;
}

public class NodesProperties {

    private String kind;
    private String image;
    private List<String> ports;
    private String group;
    private String startupConfig;
}

public class Link {

    private List<String> endpoints;
}

With the above code I am able to achieve below config-

name: srlceostopo
topology:
  nodes:
    srl1:
      kind: nokia_srlinux
      image: ghcr.io/nokia/srlinux
      group: leaf
      ports:
      - '1000:22'
    ceos1:
      kind: ceos
      image: ceos:4.32.0.1F
      group: leaf
      ports:
      - '2000:22'
    srl2:
      kind: nokia_srlinux
      image: ghcr.io/nokia/srlinux
      group: leaf
      ports:
      - '3000:22'
  links:
    - endpoints: ["srl1:e1-1", "ceos1:eth1"]
    - endpoints: ["srl2:e1-1", "srl1:e1-2"]
    - endpoints: ["srl2:e1-2", "ceos1:eth3"]

Please note –
With one port, the config is generated fine.
ports:
– ‘2000:22’

But when I am trying to add 2 ports, the yaml file is breaking. Instead of reading it as string, it is reading it as numbers.
e.g.

ports:
- '2000:22
- 3000:80

This error causing issue while executing the yaml in other places.

Question – How can I update my code so that it can generate the configuration for ports in String i.e. with double quotes or single quotes

Please Note – Because of the issue, right now I have modified the GUI to accept only 1 port. I want to enable multiple ports and generate configurations accordingly.

I have alreaty tried with Representer, but I am not getting appropriate result with it.

`
 Representer representer = new Representer(options) {
                @Override
                protected Node representScalar(Tag tag, String value) {
                    // Ensure all scalar values are double-quoted
                    return super.representScalar(tag, value, DumperOptions.ScalarStyle.DOUBLE_QUOTED);
                }
            };
`
...
`
if (nodeProps.getPorts() != null && !nodeProps.getPorts().isEmpty()) {
                    List<String> ports = nodeProps.getPorts().stream()
                            .map(port -> """ + port + """)
                            .collect(Collectors.toList());
                    nodeDetails.put("ports", ports);
                }
`

I want the code to generate yaml file with multiple ports in string format

ports:
- "2000:22"
- "3000:80"