java - 如何将 json ListView 上选定项目的值发送到另一个 Activity ？

Question

我正在制作一个应用程序，它从 JSON 获取国家/地区数据(名称、纬度、经度等)并创建一个 listview，其中每个项目都是一个不同的国家。

该部分正在工作，但是每次我单击一个项目时，它都会打开 MapActivity， map 以该国家/地区为中心。问题是我无法将坐标从 MainActivity 发送到 MapsActivity。

public class TodasAsCategorias extends AppCompatActivity {

private String TAG = TodasAsCategorias.class.getSimpleName();
private ProgressDialog pDialog;
private ListView lv;
private static String url = "http://*************/api/continent/any/country/all?id=siF1uXXEsltXOi5CWlSIzy7EABlnE5iF33bnNmfAHJiYXYNmjY";
ArrayList<HashMap<String, String>> listaPaises;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_todas_as_categorias);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setTitle("Categorias");

    listaPaises = new ArrayList<>();
    lv = (ListView) findViewById(R.id.list);
    new GetPaises().execute();
}


@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            finish();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.main, menu);
    menu.findItem(R.id.spinner_cat).setVisible(false);
    menu.findItem(R.id.spinner_pais).setVisible(false);
    return true;
}

private class GetPaises extends AsyncTask<Void, Void, Void> implements Serializable {
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(TodasAsCategorias.this);
        pDialog.setMessage("Aguarde...");
        pDialog.setCancelable(false);
        pDialog.show();
    }

    @Override
    protected Void doInBackground(Void... params) {
        HttpHandler sh = new HttpHandler();
        final String jsonStr = sh.makeServiceCall(url);
        Log.e(TAG, "Response from URL: " + jsonStr);
        if (jsonStr != null) {
            try {
                JSONArray array = new JSONArray(jsonStr);
                for (int i = 0; i < array.length(); i++) {
                    JSONObject jsonObject = array.getJSONObject(i);
                    JSONArray paises = jsonObject.optJSONArray("paises");
                    if (paises != null) {
                        for (int j = 0; j < paises.length(); j++) {
                            JSONObject jsonObject1 = paises.getJSONObject(j);

                            String K_PAIS = jsonObject1.getString("K_PAIS");
                            String Designacao = jsonObject1.getString("Designacao");
                            String URL_IMAGE_SMALL = jsonObject1.getString("URL_IMAGE_SMALL");
                            String Coord_LAT = jsonObject1.getString("Coord_LAT");
                            String Coord_LONG = jsonObject1.getString("Coord_LONG");
                            String Coord_Zoom = jsonObject1.getString("Coord_Zoom");

                            HashMap<String, String> pais = new HashMap<>();

                            pais.put("K_PAIS", K_PAIS);
                            pais.put("Designacao", Designacao);
                            pais.put("URL_IMAGE_SMALL", URL_IMAGE_SMALL);
                            pais.put("Coord_LAT", Coord_LAT);
                            pais.put("Coord_LONG", Coord_LONG);
                            pais.put("Coord_Zoom", Coord_Zoom);

                            listaPaises.add(pais);
                        }
                    }
                }
            } catch (final JSONException e) {
                Log.e(TAG, "Json parsing error: " + e.getMessage());
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(), "Json parsin error: " + e.getMessage(), Toast.LENGTH_LONG).show();
                    }
                });
            }

        } else {
            Log.e(TAG, "Couldn't get json from server.");
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(), "Couldn't get json from server. Check LogCat for possible errpr!", Toast.LENGTH_LONG).show();
                }
            });
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        if (pDialog.isShowing()) {
            pDialog.dismiss();
        }
        ListAdapter adapter = new SimpleAdapter(TodasAsCategorias.this, listaPaises, R.layout.list_item, new String[]{ "Designacao","Coord_LAT", "Coord_LONG", "Coord_Zoom"},
                new int[]{R.id.Designacao,R.id.Lat, R.id.Long, R.id.Zoom});
        lv.setAdapter(adapter);
        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> pare, View view, int position, long id) {
                Intent intent = new Intent(TodasAsCategorias.this, MapsActivity.class);

                startActivity(intent);
            }
        });
    }
}
}

Answer 1

HashMap实现了 Serialized，因此我们可以使用 putExtra 发送 HashMap 对象并使用 getSerializableExtra 接收它

TodasAsCategorias Activity

  @Override
  public void onItemClick(AdapterView<?> pare, View view, int position, long id)     
  {
       Intent intent = new Intent(TodasAsCategorias.this, MapsActivity.class);
       intent.putExtra("data", listaPaises.get(position));
       startActivity(intent);
  }

在MapsActivity中

protected void onCreate(Bundle bundle) {
    super.onCreate(savedInstanceState);

    Intent intent = getIntent();
    HashMap<String, String> hashMap = (HashMap<String, String>)intent.getSerializableExtra("data");
    String lat = hashMap.get("Coord_LAT");
    String longi = hashMap.get("Coord_LONG");
}