java - How to maintain ManyToMany -

there entities cookbook, recipe. it's manytomany relation: cookbook can have multiple recipes , recipe can assigned multiple cookbooks. added entity cookbookrecipe , connected entities onetomany.

where put method add/remove relation between cookbook , recipe - method has add new cookbookrecipe , add cookbookrecipe cookbook , recipe? in understanding expect

public void addrecipe(recipe recipe) {    cookbookrecipe relation = new cookbookrecipe();    relation.setcookbook(this);    relation.setrecipe(recipe);    this.cookbookrecipes.add( relation ); } 

is right direction? add method cookbook dao or recipe dao or put service?

@entity public class cookbook {     private integer id;     private string title;     private collection<cookbookrecipe> cookbookrecipes;     private collection<cookbooksortlevel> cookbooksortlevels;      @id     @generatedvalue(strategy = generationtype.identity)     @column(name = "id")     public integer getid() {         return id;     }      public void setid(integer id) {         this.id = id;     }      @basic     @column(name = "title")     public string gettitle() {         return title;     }      public void settitle(string title) {         this.title = title;     }      @override     public boolean equals(object o) {         if (this == o) return true;         if (o == null || getclass() != o.getclass()) return false;          cookbook cookbook = (cookbook) o;          if (id != null ? !id.equals(cookbook.id) : cookbook.id != null) return false;         if (title != null ? !title.equals(cookbook.title) : cookbook.title != null) return false;          return true;     }      @override     public int hashcode() {         int result = id != null ? id.hashcode() : 0;         result = 31 * result + (title != null ? title.hashcode() : 0);         return result;     }      @onetomany(mappedby = "cookbook", fetch = fetchtype.eager)     public collection<cookbookrecipe> getcookbookrecipes() {         return cookbookrecipes;     }      public void setcookbookrecipes(collection<cookbookrecipe> cookbookrecipes) {         this.cookbookrecipes = cookbookrecipes;     }      @onetomany(mappedby = "cookbook")     public collection<cookbooksortlevel> getcookbooksortlevels() {         return cookbooksortlevels;     }      public void setcookbooksortlevels(collection<cookbooksortlevel> cookbooksortlevels) {         this.cookbooksortlevels = cookbooksortlevels;     } }  @entity @table(name = "cookbook_recipe", schema = "", catalog = "") public class cookbookrecipe {     private integer id;     private recipe recipe;     private cookbook cookbook;      @id     @generatedvalue(strategy = generationtype.identity)     @column(name = "id")     public integer getid() {         return id;     }      public void setid(integer id) {         this.id = id;     }      @override     public boolean equals(object o) {         if (this == o) return true;         if (o == null || getclass() != o.getclass()) return false;          cookbookrecipe = (cookbookrecipe) o;          if (id != null ? !id.equals(that.id) : that.id != null) return false;          return true;     }      @override     public int hashcode() {         int result = id != null ? id.hashcode() : 0;         return result;     }      @manytoone     @joincolumn(name = "recipe_id", referencedcolumnname = "id")     public recipe getrecipe() {         return recipe;     }      public void setrecipe(recipe recipe) {         this.recipe = recipe;     }      @manytoone     @joincolumn(name = "cookbook_id", referencedcolumnname = "id", nullable=false,insertable=false,updatable=false )     public cookbook getcookbook() {         return cookbook;     }      public void setcookbook(cookbook cookbook) {         this.cookbook = cookbook;     } }   @entity public class recipe {     private integer id;     private string title;     private string text;      private collection<recipeingredient> recipeingredients;      @id     @generatedvalue(strategy = generationtype.identity)     @column(name = "id")     public integer getid() {         return id;     }      public void setid(integer id) {         this.id = id;     }      @basic     @column(name = "title")     public string gettitle() {         return title;     }      public void settitle(string title) {         this.title = title;     }      @basic     @column(name = "text")     public string gettext() {         return text;     }      public void settext(string text) {         this.text = text;     }      @override     public boolean equals(object o) {         if (this == o) return true;         if (o == null || getclass() != o.getclass()) return false;          recipe recipe = (recipe) o;          if (id != null ? !id.equals(recipe.id) : recipe.id != null) return false;         if (title != null ? !title.equals(recipe.title) : recipe.title != null) return false;         if (text != null ? !text.equals(recipe.text) : recipe.text != null) return false;          return true;     }      @override     public int hashcode() {         int result = id != null ? id.hashcode() : 0;         result = 31 * result + (title != null ? title.hashcode() : 0);         result = 31 * result + (text != null ? text.hashcode() : 0);         return result;     }      @onetomany(mappedby = "recipe")     public collection<recipeingredient> getrecipeingredients() {         return recipeingredients;     }      public void setrecipeingredients(collection<recipeingredient> recipeingredients) {         this.recipeingredients = recipeingredients;     } } 

are there github projects handling suggest?

this is, me, right direction. code looks good

i think should add in cookbookdao because cookbook contains recipes not opposite