Set background for items in a spinner using a drawable resource - java android studio

Question

I've created a spinner using the code below. Now I want to use a drawable resource called circle.xml, to set the background for each item in the spinner so that each number appears inside a circle.

        Spinner equationSpinner = new Spinner(this);

        ArrayList<String> spinnerArray = new ArrayList<String>();
        spinnerArray.add("");
        spinnerArray.add("1");
        spinnerArray.add("2");
        spinnerArray.add("3");
        spinnerArray.add("4");
        spinnerArray.add("5");

        ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, spinnerArray);
        equationSpinner.setAdapter(spinnerArrayAdapter);

I can use the circle as a background in a TextView so I tried creating the spinnerArray as an array of TextViews but that appeared to be incompatible with the simple_spinner_dropdown_item. Anybody have an idea how I can do this? I just want each number to appear inside a circle in the spinner. I will also need to be able to access the number selected in the spinner. Thanks

P.S. Is there any way in Android to create a 'slot machine' style spinner like you have in iOS? I prefer the look of those.

EDIT: I've now found that I can use my circle resource by creating a custom layout (called spinner_item.xml) like this:

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="28dip"
    android:layout_height="28dip"
    android:gravity="center"
    android:textSize="20sp"
    android:background="@drawable/circle"
    android:textColor="#ff0000" />

I then set the adapter for my spinner programmatically like this:

ArrayAdapter adapter = ArrayAdapter.createFromResource(this, R.array.equations, R.layout.spinner_item);
        adapter.setDropDownViewResource(R.layout.spinner_item);
        equationSpinner.setAdapter(adapter);

However, this method requires that I have a predefined string array set up in my strings.xml file (R.array.equations). I need to be able to specify the array of strings to be used programmatically depending on the state of the app. Can I modify the array once its set up?

EDIT 2: Additionally I've found I can set the background of the dropdown items and use my own programmatical array like this:

ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, spinnerArray);
        spinnerArrayAdapter.setDropDownViewResource(R.layout.spinner_item);
        equationSpinner.setAdapter(spinnerArrayAdapter);

The only problem then is being able to apply the resource to the background of the spinner itself (not the drop down items). There does not appear to be an equivalent to setDropDownViewResource for the main spinner item.

Answer 1

Check this answer about Android Wheel: https://stackoverflow.com/a/9503372/3677394

There's a very good 3rd party open source project called Android Wheel that pretty much does everything involved in creating a slot machine for you. And if you want to customise it, it's under an Apache licence, so no issues there.

Answer 2

lets say textview_background.xml is the background you want to give to the textView to Spinner

make a file in drawable and name it this textview_background.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="@android:color/holo_blue_dark" />
<corners android:radius="7dp" />
<stroke
    android:width="3dp"
    android:color="@android:color/tertiary_text_light" />
</shape>

make a Spinner in your activity

 <Spinner
    android:id="@+id/SpinnerOneActivity_spinner"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" />

make a layout with name list_text_view.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/text1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:minHeight="?android:attr/listPreferredItemHeightSmall"
android:padding="4dp"
android:text="some"
android:background="@drawable/textview_background"
android:textAppearance="?android:attr/textAppearanceListItemSmall"
android:textColor="@android:color/black" />

make a class which will fill data from a list to your spinner, in this code your Adapter class is taking list of String but you can have your own custom object list given to it to populate the spinner, watch out how adapter's constructor parameters.

first-Context

Second-layout which will be given to each item in spinner

Third-a textView id from the above layout

Forth-your list of objects which you want to populate

TestAdapter.java

public class TestAdapter extends ArrayAdapter {

private ArrayList<String> strings;
private Context context;
private LayoutInflater layoutInflater;

public TestAdapter(Context context, int resource,int id, ArrayList<String> strings) {
    super(context, resource, id, strings);
    this.context = context;
    this.strings = strings;
    this.layoutInflater = LayoutInflater.from(this.context);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View view = layoutInflater.inflate(R.layout.list_text_view, parent, false);
    TextView textView = (TextView) view.findViewById(R.id.text1);
    textView.setText("" + strings.get(position));
    return view;
}
}

in your activity you can write this code

 ArrayList<String> list = new ArrayList<>();
    list.add("one");
    list.add("Two");
    list.add("Three");
    list.add("four");
    Spinner spinner = (Spinner) findViewById(R.id.SpinnerOneActivity_spinner);
    spinner.setAdapter(new TestAdapter(getApplicationContext(), R.layout.list_text_view, R.id.text1,list));

As you wanted you can increase the list or generate things dynamically to add or remove from the list once your list is attached to adapter which will be provided to Spinner you can call notifyDataSetChanged() on adapter to updated the list