在单击时显示视图（活动）中相关的数据

Question

我从我的Api中获取我的Json对象/数组，并将其打印到我的视图中，foreach数组我在mainactivity中打印id和名称。

________________________
id     name      button      <- if one clicks on the button another activity shall show the description of it
________________________

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {


    private final static String TAG = MainActivity.class.getSimpleName();

    private ProgressDialog pDialog;
    private ListView lv;

    // URL to get contacts JSON
    private static String url = "http://192.168.178.58:8888/test";

    ArrayList<HashMap<String, String>> contactList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        contactList = new ArrayList<>();

        new GetContacts().execute();

        lv = (ListView) findViewById(R.id.list);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

    }

    /**
     * Async task class to get json by making HTTP call
     */
    private class GetContacts extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Showing progress dialog
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setCancelable(false);
            pDialog.show();

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            HttpHandler sh = new HttpHandler();

            // Making a request to url and getting response
            String jsonStr = sh.makeServiceCall(url);

            if (jsonStr != null) {
                try {
                    // Getting JSON Array node
                    JSONArray jsonArray = new JSONArray(jsonStr);

                    // looping through All Contacts
                    for (int i = 0; i < jsonArray.length(); i++) {
                        JSONObject c = jsonArray.getJSONObject(i);

                        String id = c.getString("id");
                        String name = c.getString("name");
                        String description = c.getString("description");

                        // tmp hash map for single contact
                        HashMap<String, String> data = new HashMap<>();

                        // adding each child node to HashMap key => value
                        data.put("id", id);
                        data.put("name", name);
                        data.put("description", description);

                        // adding contact to contact list
                        contactList.add(data);
                    }
                } catch (final JSONException e) {
                    Log.e(TAG, "Json parsing error: " + e.getMessage());
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(getApplicationContext(),
                                    "Json parsing 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 errors!",
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }

            return null;
        }

        /**
         * In onPostExecute() method the progress dialog is dismissed and the array list data is displayed in list view using an adapter.
         * @param result
         */
        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            // Dismiss the progress dialog
            if (pDialog.isShowing())
                pDialog.dismiss();
            /**
             * Updating parsed JSON data into ListView
             */
            ListAdapter adapter = new SimpleAdapter(
                    MainActivity.this, contactList,
                    R.layout.list_item,
                    new String[]{"name", "description"},
                    new int[]{R.id.name, R.id.description});

            lv.setAdapter(adapter);
        }

    }

}

这就是我的意图：

public void openDetails() { // button onclick name
   Intent myIntent = new Intent(MainActivity.this, DetailActivity.class);
    myIntent.putExtra("key", value);
    MainActivity.this.startActivity(myIntent);
}

Answer 1

public class MyData {
  private Object data;
  public Object getData() {
   return data;
  }
  public void setData(Object data) {
   this.data = data;
  }

  private static final MyData myData = new MyData();
  public static MyData getInstance() {
   return myData;
  }
}

那么在第一个活动中：

MyData.getInstance().setData(objToShare);

第二个是：

objShared = MyData.getInstance().getData();
//do something