根据选择将 JSON 数据输入 Spinner

Data is coming form JSON RESPONSE. In JSON, Every Tag contains number of nodes. Relevant data into second spinner is based on selection of First. My JSON Is Like Here

如何解析 JSON 并首先将所有主要节点解析为 First Spinner。然后当用户选择点时，根据选择的数据必须反映到第二个微调器中。请指导我。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // Download JSON file AsyncTask
    new DownloadJSON().execute();

}

// Download JSON file AsyncTask
private class DownloadJSON extends AsyncTask<Void, Void, Void> {

    @Override
    protected Void doInBackground(Void... params) {
        // Locate the WorldPopulation Class 
        world = new ArrayList<WorldPopulation>();
        // Create an array to populate the spinner 
        worldlist = new ArrayList<String>();
        // JSON file URL address
        jsonobject = JSONfunctions
                .getJSONfromURL("http://www.androidbegin.com/tutorial/jsonparsetutorial.txt");

        try {
            // Locate the NodeList name
            jsonarray = jsonobject.getJSONArray("worldpopulation");
            for (int i = 0; i < jsonarray.length(); i++) {
                jsonobject = jsonarray.getJSONObject(i);

                WorldPopulation worldpop = new WorldPopulation();

                worldpop.setRank(jsonobject.optString("rank"));
                worldpop.setCountry(jsonobject.optString("country"));
                worldpop.setPopulation(jsonobject.optString("population"));
                worldpop.setFlag(jsonobject.optString("flag"));
                world.add(worldpop);

                // Populate spinner with country names
                worldlist.add(jsonobject.optString("country"));

            }
        } catch (Exception e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void args) {
        // Locate the spinner in activity_main.xml
        Spinner mySpinner = (Spinner) findViewById(R.id.my_spinner);

        // Spinner adapter
        mySpinner
                .setAdapter(new ArrayAdapter<String>(MainActivity.this,
                        android.R.layout.simple_spinner_dropdown_item,
                        worldlist));

        // Spinner on item click listener
        mySpinner
                .setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

                    @Override
                    public void onItemSelected(AdapterView<?> arg0,
                            View arg1, int position, long arg3) {
                        // TODO Auto-generated method stub
                        // Locate the textviews in activity_main.xml
                        TextView txtrank = (TextView) findViewById(R.id.rank);
                        TextView txtcountry = (TextView) findViewById(R.id.country);
                        TextView txtpopulation = (TextView) findViewById(R.id.population);

                        // Set the text followed by the position 
                        txtrank.setText("Rank : "
                                + world.get(position).getRank());
                        txtcountry.setText("Country : "
                                + world.get(position).getCountry());
                        txtpopulation.setText("Population : "
                                + world.get(position).getPopulation());
                    }

                    @Override
                    public void onNothingSelected(AdapterView<?> arg0) {
                        // TODO Auto-generated method stub
                    }
                });
    }
}

这段代码可以让您了解如何填充对象JSON您可以从 API 获取。

你想要做的事情非常简单，但我试图让事情尽可能通用，这样其他人就不能使用这段代码。

the spinner代码中表示的填充为ArrayList of WorldPopulation类型。你会注意到toString of WorldPopulation被覆盖，它可以用在ArrayAdapter所以国家的名字将会被选取。

public class LoadDataActivity extends AppCompatActivity {

    private Spinner spinner;
    private ArrayList<WorldPopulation> worldPopulations;

    private TextView rank_TextView;
    private TextView country_TextView;
    private TextView population_TextView;
    private TextView url_TextView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_load_data);


        spinner = (Spinner) findViewById(R.id.LoadDataActivity_spinner);

        rank_TextView = (TextView) findViewById(R.id.LoadDataActivity_rank_textView);
        country_TextView = (TextView) findViewById(R.id.LoadDataActivity_country_textView);
        population_TextView = (TextView) findViewById(R.id.LoadDataActivity_population_textView);
        url_TextView = (TextView) findViewById(R.id.LoadDataActivity_url_textView);

        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                WorldPopulation population = (WorldPopulation) spinner.getItemAtPosition(position);
                rank_TextView.setText("" + population.getRank());
                country_TextView.setText("" + population.getCountry());
                population_TextView.setText("" + population.getPopulation());
                url_TextView.setText("" + population.getFlag());
            }

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

            }
        });

        new DownloadData().execute();
    }


    private class DownloadData extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... params) {

            try {
                worldPopulations = new ArrayList<>();
                URL url = new URL("http://www.androidbegin.com/tutorial/jsonparsetutorial.txt");
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                httpURLConnection.connect();
                String result = IOUtils.toString(httpURLConnection.getInputStream());
                System.out.println("" + result);
                JSONObject jsonObject = new JSONObject(result);
                JSONArray jsonArray = jsonObject.getJSONArray("worldpopulation");
                for (int i = 0; i < jsonArray.length(); i++) {
                    JSONObject singleItem = jsonArray.getJSONObject(i);
                    WorldPopulation population = new WorldPopulation();
                    population.rank = singleItem.getString("rank");
                    population.country = singleItem.getString("country");
                    population.population = singleItem.getString("population");
                    population.flag = singleItem.getString("flag");
                    worldPopulations.add(population);
                }

                Log.d("TAG", "" + result);
                Log.d("TAG", "size: " + worldPopulations.size());
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            super.onPostExecute(aVoid);
            ArrayAdapter<WorldPopulation> adapter = new ArrayAdapter<WorldPopulation>(getApplicationContext(), android.R.layout.simple_spinner_dropdown_item, worldPopulations);
            adapter.setDropDownViewResource(android.R.layout.simple_list_item_1);
            spinner.setAdapter(adapter);
        }
    }

    class WorldPopulation {
        private String rank;
        private String country;
        private String population;
        private String flag;

        public String getRank() {
            return rank;
        }

        public void setRank(String rank) {
            this.rank = rank;
        }

        public String getCountry() {
            return country;
        }

        public void setCountry(String country) {
            this.country = country;
        }

        public String getPopulation() {
            return population;
        }

        public void setPopulation(String population) {
            this.population = population;
        }

        public String getFlag() {
            return flag;
        }

        public void setFlag(String flag) {
            this.flag = flag;
        }

        @Override
        public String toString() {
            return country;
        }
    }

}

活动加载数据.xml

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="4dp"
    android:orientation="vertical">


    <Spinner
        android:id="@+id/LoadDataActivity_spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_margin="4dp" />

    <TextView
        android:id="@+id/LoadDataActivity_rank_textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="4dp"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/LoadDataActivity_country_textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="4dp"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/LoadDataActivity_population_textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="4dp"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/LoadDataActivity_url_textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="4dp"
        android:textAppearance="?android:attr/textAppearanceMedium" />
</LinearLayout>

Output

现在您已将数据填充到Spinner您可以利用它来触发填充第二个spinner取决于第一个的选择spinner.

显然我没有看到任何链接可以告诉我第二个数据源，我将把答案留在这里直到下次更新。