The best way to store data in java with more dimensions?

Question

I have some input like :

  package 1 : org.orchestr.something  version= 5.1.3

      uses = org.do.resource   ; version= 1.2.1
      uses = org.test.summer   ; version= 1.5.2


  package 2 : fr.test.something  version= 5.1.3

      uses = com.java.rest     ; version= 1.0.1
      uses = org.osgi.summer   ; version= 1.4.2

  ....

So in this data I have set of packages defined by their version and bunch others packages that they use within a specific version, and i want to know with is the best way/ practical way to store this kind of data.

Answer 1

It sounds like you intend to represent some graph like structure.

A first naive implementation could/would be using specific classes, like Package and Entry where a Package probably has a list/set of of Entry objects (and an Entry has a name + version string).

Of course, as you are in the end intend to create some sort of graph, you probably should look into solutions such as graphql , too.

Answer 2

Something like this might work, assuming there's one-level of nested dependency in your case:

A base Artifact class:

  class Artifact {
    protected String name;
    protected String version;

    public Artifact(String name, String version) {
      this.name = name;
      this.version = version;
    }

    public String getName() {
      return name;
    }

    public void setName(String name) {
      this.name = name;
    }

    public String getVersion() {
      return version;
    }

    public void setVersion(String version) {
      this.version = version;
    }
  }

A Package class that extends Artifact and adds another parameter uses :

class Package extends Artifact {

    public Package(String name, String version, List<Artifact> uses) {
      super(name, version);
      this.uses = uses;
    }

    private List<Artifact> uses;

    public List<Artifact> getUses() {
      return uses;
    }

    public void setUses(List<Artifact> uses) {
      this.uses = uses;
    }
  }

You can then store it as a List or Map as needed.

Example of using in a Map :

    Map<String, Package> map = new HashMap<>();
    map.put("package1", new Package("org.orchestr.something", "5.1.3", Arrays.asList(
        new Artifact("org.do.resource", "1.2.1"),
        new Artifact("org.test.summer", "1.5.2")))
    );

    map.put("package2", new Package("fr.test.something", "5.1.3", Arrays.asList(
        new Artifact("com.java.rest", "1.0.1"),
        new Artifact("org.osgi.summer", "1.4.2")))
    );

Answer 3

The package and uses data look equal. So i would use a map:

class Uses { private path, version; }
Map<Uses, Set<Uses>> data;

The packages are the keys, the used dependencies are elements of the value.

Answer 4

You could model it as a map of artifacts :

import java.util.Objects;

public class Artifact {
    private String name;
    private String version;

    public Artifact(String name, String version) {
        this.name = name;
        this.version = version;
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Artifact that = (Artifact) o;
        return version.equals(that.version) &&
                name.equals(that.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(version, name);
    }
}

And here would be a usage of this :

    public static void main(String[] args) {
        Map<Artifact, Set<Artifact>>  map = new HashMap<>();


        Set<Artifact> dependencies = new HashSet<>();
        dependencies.add(new Artifact("org.do.resource ", "1.2.1"));
        dependencies.add(new Artifact("org.test.summer ", "1.5.2"));

        map.put(new Artifact("org.orchestr.something", "5.1.3"), dependencies);
    }

I had to override equals and hashcode methods for Artifact class because objects of this class will be used as keys in HashMap . If you want to also support package version just add such field to Artifact class and add apropriate constructor, getters, setters and modify equals and hashcode methods accordingly.