我只是通过在JSON的帮助下获取数据来更新我的列表视图，但是我想通过递增计数器来每5秒执行一次，这意味着;当计数器在获取数据后> gt = = 5然后将计数器设置为0，因此当它为5时它将再次刷新。
使数据完美无缺，没有检查计数器值的if语句。
当if语句为真时，我不确定在哪里键入if语句来获取结果。
这是我的全班;
public class AllProductsActivity extends ListActivity {
int delay = 5000; // delay for 5 sec.
int period = 1000; // repeat every sec.
int counterr=0;
// Progress Dialog
private ProgressDialog pDialog;
public boolean refresh=false;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> productsList;
// url to get all products list
private static String url_all_products = "http://XXXXXXX.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "products";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
private static final String TAG_PRICE = "price";
private static final String TAG_DESCRIPTION = "description";
// products JSONArray
JSONArray products = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_products);
//counterr=100;
Timer timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask()
{
public void run()
{
// Your code
counterr++;
System.out.println("COun "+counterr);
System.out.println("Refresh? "+refresh);
if(counterr>=3)
refresh=true;
}
}, delay, period);
// Hashmap for ListView
productsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProducts().execute();
// Get listview
ListView lv = getListView();
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String pid = ((TextView) view.findViewById(R.id.pid)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
EditProductActivity.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
}
// Response from Edit Product Activity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// if result code 100
if (resultCode == 100) {
// if result code 100 is received
// means user edited/deleted product
// reload this screen again
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllProducts extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllProductsActivity.this);
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
System.out.println(success);
if (success == 1){// && counterr>=5) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = 0; i < products.length(); i++) {
JSONObject c = products.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_PID);
String name = c.getString(TAG_NAME);
String price = c.getString(TAG_PRICE);
String description = c.getString(TAG_DESCRIPTION);
//if(counterr>=5){
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
map.put(TAG_PRICE, "" + price);
map.put(TAG_DESCRIPTION, description);
// adding HashList to ArrayList
productsList.add(map);
counterr=0;
refresh=false;
}
}
//counterr=0;
// }
else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
NewProductActivity.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
AllProductsActivity.this, productsList,
R.layout.list_item, new String[] { TAG_PID,
TAG_NAME, TAG_PRICE, TAG_DESCRIPTION},
new int[] { R.id.pid, R.id.name, R.id.price, R.id.description });
// updating listview
setListAdapter(adapter);
}
});
}
}
}
答案 0 :(得分：0)
似乎你不需要在TimerTask中放入任何if条件。如果要在5秒后启动计时器，则每5秒启动一次计时器。而不是
int delay = 5000; // delay for 5 sec.
int period = 5000; // repeat after every 5 sec.
如果您想立即启动任务，请将延迟减少到最小值。
试试希望它会起作用。
答案 1 :(得分：0)
通过实施这一点;在public void run（）{
中 if(counterr>=5){
counterr=0;
json = jParser.makeHttpRequest(url_all_products, "GET", params);
Intent i = new Intent(getApplicationContext(), AllProductsActivity.class);
startActivity(i);
}
诀窍！