Thread: Please help with correcting error "NON STATIC METHOD CANNOT BE CALLED FROM STATIC CONTEXT"

To call a non-static method, the code needs to have a reference to an instance of the class and use that reference to call the method:

   refToClass.theMethodToCall();  // call non-static method

To call a static method, use the classname dot method name:

  TheClassName.theStaticMethod();  // call static method

Please post here any code that you are asking about. Not as an attachment or link.

Thank you I tried to post my code initially but it gave me an error so I ended up having to attach it so in this case its referencing a method called addNewRecipe in another class called Recipe. I currently have it as this.listOfRecipes.add(Recipe.addNewRecipe());. Based on what you are saying should it be changed to this this.listOfRecipes.add(RecipeBox.addNewRecipe());? ?

See full code below:

package Final;

import java.util.ArrayList;

/**
*
* @author rijackson
*/
public class RecipeBox {
//Single private instance field
private ArrayList<Recipe> listOfRecipes;

/**
*Constructor for recipe box
*/
public RecipeBox() {
this.setListOfRecipes(new ArrayList<>());
}

/**
*
* @param listOfRecipes
*/
public RecipeBox(ArrayList<Recipe> listOfRecipes) {
this.setListOfRecipes(listOfRecipes);
}



//Accessor and mutator for list of recipes
/**
*
* @return list of recipes
*/
public ArrayList<Recipe> getListOfRecipes() {
return listOfRecipes;
}

/**
*
* @param listOfRecipes the list of recipes
*/
public void setListOfRecipes(ArrayList<Recipe> listOfRecipes) {
this.listOfRecipes = listOfRecipes;
}


/**
* method to add new recipe to the collection
*/
public void addNewRecipe() {
//call into static method on recipe class
this.listOfRecipes.add(Recipe.addNewRecipe());
}

//print all recipe names

/**
* Method to print all recipe names
*/
public void printAllRecipeNames() {
for(Recipe r : listOfRecipes) { //iterate over list
System.out.println(r.getRecipeName()); //print the name
}
}

/**
*
* @param name
*/
public void printRecipeDetails(String name) {
Recipe r = findRecipe(name); //look for recipe
if(r == null) { //if none found, notify user
System.out.println("Recipe not found");
} else {
r.printRecipe();//print full details
}
}

/**
*
* @param name
*/
public void deleteRecipe(String name) {
Recipe r = findRecipe(name); //find recipe by name
if(r == null) { //if no match, notify user
System.out.println("Recipe not found");
} else {
listOfRecipes.remove(r); //remove recipe from list
}
}

//helper to find a recipe by name
//Returns null if no match is found
private Recipe findRecipe(String name) {
for(Recipe r : listOfRecipes) {
if(r.getRecipeName().equals(name)) {
return r;
}
}
return null;
}
}

--- Update ---

Thank you I tried to post my code initially but it gave me an error so I ended up having to attach it. So in this case its referencing a method called addNewRecipe in another class called Recipe. I currently have it as this.listOfRecipes.add(Recipe.addNewRecipe());. Based on what you are saying should it be changed to this this.listOfRecipes.add(RecipeBox.addNewRecipe());? ?

See full code below:

package Final;
 
import java.util.ArrayList;
 
/**
 * 
 * @author rijackson
 */
public class RecipeBox {
	//Single private instance field
	private ArrayList<Recipe> listOfRecipes;
 
     /**
     *Constructor for recipe box
     */
	public RecipeBox() {
		this.setListOfRecipes(new ArrayList<>());
	}
 
    /**
     * 
     * @param listOfRecipes
     */
    public RecipeBox(ArrayList<Recipe> listOfRecipes) {
		this.setListOfRecipes(listOfRecipes);
	}
 
 
 
      //Accessor and mutator for list of recipes
    /**
     *
     * @return list of recipes
     */
	public ArrayList<Recipe> getListOfRecipes() {
		return listOfRecipes;
	}
 
    /**
     *
     * @param listOfRecipes the list of recipes
     */
    public void setListOfRecipes(ArrayList<Recipe> listOfRecipes) {
		this.listOfRecipes = listOfRecipes;
	}
 
 
    /**
     * method to add new recipe to the collection
     */
	public void addNewRecipe() {
            //call into static method on recipe class
            this.listOfRecipes.add(Recipe.addNewRecipe());
	}
 
	//print all recipe names 
 
    /**
     * Method to print all recipe names
     */
	public void printAllRecipeNames() {
		for(Recipe r : listOfRecipes) { //iterate over list
			System.out.println(r.getRecipeName()); //print the name
		}
	}
 
    /**
     * 
     * @param name
     */
	public void printRecipeDetails(String name) {
		Recipe r = findRecipe(name); //look for recipe
		if(r == null) { //if none found, notify user
			System.out.println("Recipe not found");
		} else {
			r.printRecipe();//print full details
		}
	}
 
    /**
     *
     * @param name
     */
    public void deleteRecipe(String name) {
		Recipe r = findRecipe(name); //find recipe by name
		if(r == null) { //if no match, notify user
			System.out.println("Recipe not found");
		} else {
			listOfRecipes.remove(r); //remove recipe from list
		}
	}
 
	//helper to find a recipe by name
	//Returns null if no match is found
	private Recipe findRecipe(String name) {
		for(Recipe r : listOfRecipes) {
			if(r.getRecipeName().equals(name)) {
				return r;
			}
		}
		return null;
	}
}

   this.listOfRecipes.add(Recipe.addNewRecipe());

What class is the method addNewRecipe defined in? The Recipe class was not posted.
Is there a reference to an instance of that class that is available when you want to call the method?

The syntax of the expression: Recipe.addNewRecipe() says that addNewRecipe is a static method in the Recipe class.



Please edit your post and wrap your code with code tags:

[code]
**YOUR CODE GOES HERE**
[/code]

to get highlighting and preserve formatting.

The addNewRecipe() method is not static, so it can not be called using the static syntax as I mentioned above.

Can it be changed to a static method?

Otherwise there needs to be a reference to an instance of the Recipe class that can be used as I mentioned above.

ahh ok I changed it to static and that removed the error message there but then it placed that same error message on this part of the code in the Recipe class now which is referring to the getRecipeIngredients() accsessor.

 
	            //Add the total Calories from this ingredient 
	            totalRecipeCalories = totalRecipeCalories + (ingredientCalories * ingredientAmount);      
	            [COLOR="#FF0000"]getRecipeIngredients().add(thisIngredient);[/COLOR]
            }
 
 
       } while (addMoreIngredients); //looping to add ingredients from user unless "end" 
                //create new recipe with user inputs 
               [COLOR="#FF0000"] Recipe recipe = new Recipe(recipeName,servings, (ArrayList<Ingredient>) getRecipeIngredients(), totalRecipeCalories);[/COLOR]
                recipe.printRecipe();
                return recipe;
 
 
    }

Could you give me an example of what an instance of the Recipe class would look like in this case? that may be what I need vs making the method static.

example of what an instance of the Recipe class would look like

An instance of a class is created with a new statement that calls the class's constructor. The following statement from your code creates an instance of the Recipe class and saves the reference in the recipe variable:

 Recipe recipe = new Recipe(recipeName,servings, (ArrayList<Ingredient>) getRecipeIngredients(), totalRecipeCalories);

same error message on this part of the code in the Recipe class

You can not make a method static if it uses other parts of the class that are not static.
The ingredients for a recipe belong to one recipe so their values can not be static (meaning shared between all instances of a class).

Look at where the original problem is. What recipe is it working with? The code needs a reference to that recipe so it can call one of its methods.