CODEWITHSUNDEEP
javaandroid
Kaloyan Roussev
Kaloyan Roussev

Reputation: 14711

Is it possible to merge these two methods in one, possibly using.. polymorphism?

In my android application I have ItemCategory POJO and ItemSubcategory POJO that both extend Category POJO holding some common characteristics.

I have a custom Load Spinner method that I pass an ArrayList of Objects to, and it loads them into a spinner (the Android name for drop-down/select)

I tried passing an ArrayList to a single method loadCategoriesIntoSpinner( that accepts an ArrayList as a parameter) and I expected it to sort out that what Im passing is an ArrayList but it didnt. 

public static void loadCategoriesIntoSpinner(Context context, ArrayList<ItemCategory> array, Spinner spinner) {

    // Creating adapter for spinner
    ArrayAdapter<ItemCategory> dataAdapter = new ArrayAdapter<ItemCategory>(context,
            R.drawable.simple_spinner_item, array);

    // Drop down layout style - list view with radio button
    dataAdapter
            .setDropDownViewResource(R.drawable.simple_spinner_dropdown_item);

    // Attaching data adapter to spinner
    spinner.setAdapter(dataAdapter);
}

public static void loadSubcategoriesIntoSpinner(Context context, ArrayList<ItemSubcategory> array, Spinner spinner) {

    // Creating adapter for spinner
    ArrayAdapter<ItemSubcategory> dataAdapter = new ArrayAdapter<ItemSubcategory>(context,
            R.drawable.simple_spinner_item, array);

    // Drop down layout style - list view with radio button
    dataAdapter
            .setDropDownViewResource(R.drawable.simple_spinner_dropdown_item);

    // Attaching data adapter to spinner
    spinner.setAdapter(dataAdapter);
}

Here are the Category objects:

Main class Category:

abstract public class Category {

    private int id;
    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return this.name;
    }

} // End of Class

inheriting class ItemCategory

public class ItemCategory extends Category {

    private String logo;

    public String getLogo() {
        return logo;
    }

    public void setLogo(String logo) {
        this.logo = logo;
    }

}  // End of Class

inheriting class ItemSubcategory:

public class ItemSubcategory extends Category {

    private int parentID;

    public void setParentID(int parentID) {
        this.parentID = parentID;
    }

    public int getParentID() {
        return parentID;
    }

}  // End of Class

Upvotes: 0

Views: 102

Answers (2)

lance-java
lance-java

Reputation: 27984

public static void <T extends Category> loadCategoriesIntoSpinner(Context context, List<T> array, Spinner spinner) {
    ArrayAdapter<T> dataAdapter = new ArrayAdapter<T>(context, R.drawable.simple_spinner_item, array);
    ...

Upvotes: 2

m0skit0
m0skit0

Reputation: 25873

public static void loadSubcategoriesIntoSpinner(Context context, List<? extends Category> array, Spinner spinner)

or also

public static void loadSubcategoriesIntoSpinner(Context context, List<Category> array, Spinner spinner)

if you create your list as List<Category>.

I suggest you use the interface List instead of a specific implementation like ArrayList. This way you can change the implementation (to LinkedList for example) without having to modify your code.

Upvotes: 3

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