public class Product implements Serializable {
    Category category;
    public Long id;
    public String name;
    public List<String> photoUrls = new ArrayList<String>();
    public String status;
    public List<Tag> tags = new ArrayList<Tag>();



    public Product(Long id, String name, List<String> photoUrl) {
        this.id = id;
        this.name = name;
        this.photoUrls = photoUrl; 
    }


    public Product(Long id, String name) {
        this.id = id;
        this.name = name;
        this.photoUrls.add(" ");
    }



    public Product() {
        this.id = -1L;
    }

    public Product(Category category, Long id, String name, List<String> photoUrls, String status, List<Tag> tags) {
        this.category = category;
        this.id = id;
        this.name = name;
        this.photoUrls = photoUrls;
        this.status = status;
        this.tags = tags;
    }
}

class Tag {
    int id;
    String name;

    public Tag(int id, String name) {
        this.id = id;
        this.name = name;
    }
}

class Category {
    public int id;
    public String name;

    public Category(int id, String name) {
        this.id = id;
        this.name = name;
    }
}

 Gson g = new Gson();
 Product product = g.fromJson(str, Product.class);

 Gson g = new Gson();
 Product product = g.fromJson(str, ProductList.class);