How do I use if-else in two Adapters

Question

I have two adapters, one is for the country and another is continents.

What I want to happen is: When I pick a continent in the Continent's Spinner for example "Asia", the other countries which are: "Belgium", "France", "Italy", "Germany", "Spain" will not display in the list when I click the Countries' Spinner . Thus, only the "China" will display in the list.

Note: I don't know if the codes are working right I just based the continents code from a github post and edited it.

The link where I copied the codes: https://stackoverflow.com/questions/ask

Countries Adapter and Spinner:

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                 android.R.layout.simple_dropdown_item_1line, COUNTRIES);
         BetterSpinner textView = (BetterSpinner)
                 findViewById(R.id.countries_list);
         textView.setAdapter(adapter);
     }

     private static final String[] COUNTRIES = new String[] {
         "Belgium", "France", "Italy", "Germany", "Spain", "China"
     };

Continents Adapter and Spinner:

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                 android.R.layout.simple_dropdown_item_1line, CONTINENTS);
         BetterSpinner textView = (BetterSpinner)
                 findViewById(R.id.continents_list);
         textView.setAdapter(adapter);
     }

     private static final String[] COUNTRIES = new String[] {
         "Asia", "Europe", "North America", "South America"
     };

Answer 1

You can try this

Continents Adapter and Spinner:

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                     android.R.layout.simple_dropdown_item_1line, CONTINENTS);
             BetterSpinner textView = (BetterSpinner)
                     findViewById(R.id.continents_list);
             textView.setAdapter(adapter);
             textView.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> adapterView, View view, int pos, long l) {
                    String selectedContinent=CONTINENTS[pos];
                    if(selectedContinente.equals("Asia"){
                        //Code to generate another spinner for countries
                        setCountrySpinner();    

                    }

                }

                @Override
                public void onNothingSelected(AdapterView<?> adapterView) {

                }
            });

         }

         private static final String[] CONTINENTS = new String[] {
             "Asia", "Europe", "North America", "South America"
         };

 private static final String[] ASIA_COUNTRIES = new String[] {
          "India","China"
     };

 private static final String[] OTHER_COUNTRIES = new String[] {
          "Belgium", "France", "Italy", "Germany", "Spain"
     };



private void setCountrySpinner(){
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                 android.R.layout.simple_dropdown_item_1line, ASIA_COUNTRIES);
         BetterSpinner textView = (BetterSpinner)
                 findViewById(R.id.countries_list);
         textView.setAdapter(adapter);
     }
}

Using this way you need to make diffrent array for diffrent country. This is not the best way. i recommend you to make one Model class for this like:

private class CountryModel{
      private String continentName;
      private String countryName;

}

Using this model class you can fetch country name according to ContinentName.

Answer 2

For Countries instead of String array:

private static final String[] COUNTRIES = new String[] {
     "Belgium", "France", "Italy", "Germany", "Spain", "China"
 };

Use ArrayList of String arrays:

private static ArrayList COUNTRIES = new ArrayList<>();
arrayList.add(new String[]{"Belgium", "France", "Italy", "Germany", "Spain"});
arrayList.add(new String[]{"China"});

Now according to the user's selection position on the spinner you can simply show the countries from String Array of that position in ArrayList.