Question

我有来自mysql的数据的列表视图，我想将所选项目传递给另一个活动，但总是错误空值。

这是我的活动

public class ReportActivity extends AppCompatActivity {

private String TAG = ReportActivity.class.getSimpleName();

private ProgressDialog pDialog;
private ListView lv;

// URL to get contacts JSON
private static String url = "http://demoweb.pe.hu/c_report_hp";

ArrayList<HashMap<String, String>> reportList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_report);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

    reportList = new ArrayList<>();

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

    new ReportActivity.GetLaporan().execute();
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                                int position, long id) {
            Intent intent = new Intent(getApplicationContext(), ReportDetail.class);
            intent.putExtra("area", String.valueOf(lv.getSelectedItem()));
            intent.putExtra("note", String.valueOf(lv.getSelectedItem()));
            intent.putExtra("alamat", String.valueOf(lv.getSelectedItem()));
            intent.putExtra("status", String.valueOf(lv.getSelectedItem()));
            startActivity(intent);
        }

    });
}

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

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

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(ReportActivity.this);
        pDialog.setMessage("Please wait...");
        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);

        Log.e(TAG, "Response from url: " + jsonStr);

        if (jsonStr != null) {
            try {
                JSONObject jsonObj = new JSONObject(jsonStr);

                // Getting JSON Array node
                JSONArray contacts = jsonObj.getJSONArray("laporan");

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

                    String id = c.getString("id");
                    String note = c.getString("note_infra");
                    String status = c.getString("report_status");
                    String area = c.getString("area_infra");
                    String alamat = c.getString("alamat_infra");



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

                    // adding each child node to HashMap key => value
                    contact.put("id", id);
                    contact.put("note", note);
                    contact.put("status", status);
                    contact.put("area", area);
                    contact.put("alamat", alamat);

                    // adding contact to contact list
                    reportList.add(contact);
                }
            } 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;
    }

    @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(
                ReportActivity.this, reportList,
                R.layout.list_laporan, new String[]{"area", "note",
                "alamat", "status"}, new int[]{R.id.areaInfra,
                R.id.noteInfra, R.id.alamatInfra, R.id.statusReport});

        lv.setAdapter(adapter);

    }

}
}

帮我发送listview

中的值

您的帮助将不胜感激。

Answer 1

将lv.getSelectedItem()更改为

parent.getAdapter().getItem(position)

默认情况下，当您单击ListView项目时，它不会将状态更改为 selected ，因此，当事件触发时您执行以下操作：

lv.getSelectedItem()

该方法无法返回任何内容。

Answer 2

lv.getSelectedItem()

应该是reportList.get（position）;

但是你有4个值，所以我不确定你想做什么。

正确的方法来做你想要的是一个可以Parcelable的POJO，你通过Intent传递那个对象

将数据从ListView传递到另一个活动

2 个答案: