Skip to content

Instantly share code, notes, and snippets.

@NAVNEETOJHA

NAVNEETOJHA/DependencyInversionControl.java

Created March 21, 2021 17:39
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save NAVNEETOJHA/659cfa277031f73ca76101170c4c6cd5 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save NAVNEETOJHA/659cfa277031f73ca76101170c4c6cd5 to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. NAVNEETOJHA created this gist Mar 21, 2021.
    99 changes: 99 additions & 0 deletions DependencyInversionControl.java
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,99 @@

    import org.javatuples.Triplet;

    import java.util.ArrayList;
    import java.util.List;
    import java.util.Objects;
    import java.util.stream.Collectors;

    // A. High-level modules should not depend on low-level modules.
    // Both should depend on abstractions.

    // B. Abstractions should not depend on details.
    // Details should depend on abstractions.

    enum Relationship
    {
    PARENT,
    CHILD,
    SIBLING
    }

    class Person
    {
    public String name;
    // dob etc.


    public Person(String name) {
    this.name = name;
    }
    }

    interface RelationshipBrowser
    {
    List<Person> findAllChildrenOf(String name);
    }

    class Relationships implements RelationshipBrowser
    {
    public List<Person> findAllChildrenOf(String name) {

    return relations.stream()
    .filter(x -> Objects.equals(x.getValue0().name, name)
    && x.getValue1() == Relationship.PARENT)
    .map(Triplet::getValue2)
    .collect(Collectors.toList());
    }

    // Triplet class requires javatuples
    private List<Triplet<Person, Relationship, Person>> relations =
    new ArrayList<>();

    public List<Triplet<Person, Relationship, Person>> getRelations() {
    return relations;
    }

    public void addParentAndChild(Person parent, Person child)
    {
    relations.add(new Triplet<>(parent, Relationship.PARENT, child));
    relations.add(new Triplet<>(child, Relationship.CHILD, parent));
    }
    }

    class Research
    {
    public Research(Relationships relationships)
    {
    // high-level: find all of john's children
    List<Triplet<Person, Relationship, Person>> relations = relationships.getRelations();
    relations.stream()
    .filter(x -> x.getValue0().name.equals("John")
    && x.getValue1() == Relationship.PARENT)
    .forEach(ch -> System.out.println("John has a child called " + ch.getValue2().name));
    }

    public Research(RelationshipBrowser browser)
    {
    List<Person> children = browser.findAllChildrenOf("John");
    for (Person child : children)
    System.out.println("John has a child called " + child.name);
    }
    }

    class DIPDemo
    {
    public static void main(String[] args)
    {
    Person parent = new Person("John");
    Person child1 = new Person("Chris");
    Person child2 = new Person("Matt");

    // low-level module
    Relationships relationships = new Relationships();
    relationships.addParentAndChild(parent, child1);
    relationships.addParentAndChild(parent, child2);

    new Research(relationships);
    }
    }