Question

OK so for background I’ve only been using Java for a little more than a week and I am making a basic GUI “Recipe Book” application just to test out some of the techniques I’ve learned. Currently I’m working on the “Add New Recipe” page that allows the user to make a new recipe by adding ingredients one at a time. The ingredients have 3 attributes: Name, amount, and unit (like cups, oz, etc) that come from two text fields and a combo box respectively. The 3 values are stores as strings to a String array that represents the ingredient, then the arrays are stored in a vector that holds all of the ingredients for one recipe. When an ingredient is added, the user first types in the 3 necessary values into empty boxes/combo box dropdown and then clicks “Add Ingredient”. Here is my code for when the button is clicked:

public void actionPerformed(ActionEvent event) {
    Object source = event.getSource();
    if (source == addIngredientButton) {
        //make sure 3 ingredient fields are not blank
        if (!ingredientNameField.getText().equals("") && !ingredientAmountField.getText().equals("") && !ingredientUnitDropdown.getSelectedItem().equals("")) {
            tempIngredientsArray[0] = ingredientNameField.getText(); //set ingredient name to first position in array
            tempIngredientsArray[1] = ingredientAmountField.getText(); //set ingredient amount to second position in array
            tempIngredientsArray[2] = (String) ingredientUnitDropdown.getSelectedItem(); //set ingredient unit to third position in array
            int ingredientsVectorSize = tempRecipe.ingredientsVector.size();
            tempRecipe.ingredientsVector.add(this.tempIngredientsArray);  //why would it matter if this and previous statement were switched
            for (int k = 0; k < ingredientsVectorSize + 1; k++ ) {
                liveIngredientsListArea.append("\n" + tempRecipe.makeIngredientSentence(k));
                System.out.println(Arrays.toString(tempIngredientsArray));  //shows that tempIngredientsArray gets messed up each time
                }
            }

Now here’s the really strange problem I’ve been having. The first time the user adds an ingredient everything works fine. The second time, the String[] for that ingredient seems to be duplicated, and the third time it’s triplicated. Aka the first time it runs the System.out.println might return “{Sugar, 3, Cups}” and the second time it will return “{Flour, 2, Oz.} {Flour, 2, Oz.}” etc. What’s causing this strange problem? All help greatly appreciated, let me know if you need any clarification.

Answer 1

Something I noticed:

tempRecipe.ingredientsVector.add(this.tempIngredientsArray);

That’s adding tempIngredientsArray to your vector. The array, just like that. There’s no copying going on or anything. The array, a single object, is added to the end of the vector. If you now put different values into the array, then it will contain different values. If you add the new, changed array to the vector, you will have the same array in the vector twice, with the most recent values, because… it’s the same array.

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EDIT:

My suggestion on creating the array inside the if:

if (!ingredientNameField.getText().equals("") ... {
    String[] tempIngredientsArray = new String[3];
    tempIngredientsArray[0] = ingredientNameField.getText();
        ...

… and you’ll have to remove the declaration of tempIngredientsArray wherever it is now, of course.