如果用户在微调器中选择它，我想根据价格对我的项目进行排序。我该如何实现它？下面的代码就是我所做的。我对onitem选择的用法是否正确？我必须实现OnItemSelectedListener吗？
public class SearchResults extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
JSONObject json;
ArrayList<Products> productsList = new ArrayList<Products>();
// url to get all products list
// private static String url_all_products =
// "http://10.0.2.2:8000/project/display_items.php";
// private static String url_all_products =
// "http://inticlassifields.comze.com/phpscripts/display_items.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "product";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
private static final String TAG_BUDGET = "price";
private static final String TAG_DES = "description";
private static final String TAG_DATE_POSTED = "created_at";
private static final String TAG_CATEGORY = "category";
private static final String TAG_EMAIL = "email";
private static final String TAG_CONTACT = "contact";
// products JSONArray
JSONArray products = null;
Spinner spinTop;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_results);
String[] spinnerText = { "Sort by date posted (newest first)",
"Sort by price (lowest to highest)" };
LayoutInflater inflater = LayoutInflater.from(this);
spinTop = (Spinner) inflater.inflate(R.layout.spin, null);
getListView().addHeaderView(spinTop);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, spinnerText);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinTop.setAdapter(adapter);
// Hashmap for ListView
productsList = new ArrayList<Products>();
// 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();
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String description = ((TextView) view.findViewById(R.id.des))
.getText().toString();
String price = ((TextView) view.findViewById(R.id.budget))
.getText().toString();
String date = ((TextView) view.findViewById(R.id.date_posted))
.getText().toString();
String category = ((TextView) view.findViewById(R.id.category))
.getText().toString();
String email = ((TextView) view
.findViewById(R.id.email_request)).getText().toString();
String contact = ((TextView) view
.findViewById(R.id.contact_request)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
DisplayItemInfo.class);
// sending information to next activity
in.putExtra(TAG_PID, pid);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_DES, description);
in.putExtra(TAG_BUDGET, price);
in.putExtra(TAG_DATE_POSTED, date);
in.putExtra(TAG_CATEGORY, category);
in.putExtra(TAG_EMAIL, email);
in.putExtra(TAG_CONTACT, contact);
startActivity(in);
}
});
spinTop.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View view,
int pos, long id) {
String strSpinner = spinTop.getSelectedItem().toString();
if (strSpinner.equals("Sort by price (lowest to highest)")) {
Collections.sort(productsList, new PriceSort());
}
adapter.notifyDataSetChanged();
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
});
}
/**
* 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(SearchResults.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) {
// List<NameValuePair> params = new ArrayList<NameValuePair>();
Intent intent = getIntent();
// getting attached intent data
String jsonS = intent.getStringExtra("JSon");
if (jsonS == null) {
// getting JSON string from URL
/*
* json = jParser.makeHttpRequest(url_all_products, "GET",
* params);
*/
} else {
try {
JSONObject Jsonobj = new JSONObject(jsonS);
json = Jsonobj;
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// Check your log cat for JSON reponse
Log.d("All Products: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
products = json.getJSONArray(TAG_PRODUCTS);
// looping through All Products
for (int i = products.length() - 1; i != -1; 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 budget = c.getString(TAG_BUDGET);
String description = c.getString(TAG_DES);
String category = c.getString(TAG_CATEGORY);
String contact = c.getString(TAG_CONTACT);
String email = c.getString(TAG_EMAIL);
String dateS = c.getString(TAG_DATE_POSTED);
SimpleDateFormat formatter = new SimpleDateFormat(
"yyyy-mm-dd", java.util.Locale.getDefault());
Date dateD = null;
try {
dateD = formatter.parse(dateS);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (java.text.ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
SimpleDateFormat formatter2 = new SimpleDateFormat(
"dd-mm-yyyy", java.util.Locale.getDefault());
String date = formatter2.format(dateD);
// Create a new Product Object, set its Values
Products mProduct = new Products();
mProduct.pid = id;
mProduct.name = name;
mProduct.price = budget;
mProduct.description = description;
mProduct.date = date;
mProduct.category = category;
mProduct.email = email;
mProduct.contact = contact;
// adding Product to ArrayList
productsList.add(mProduct);
}
} else {
// no products found
Intent i = new Intent(getApplicationContext(),
MainMenu.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();
if (productsList.size() > 0) {
/**
* Updating parsed JSON data into ListView
* */
CustomAdapter adapter = new CustomAdapter(getBaseContext(),
productsList);// ,
if (getListView() != null) {
// updating listview
setListAdapter(adapter);
} else {
Log.d("ListView-Reference", "ListView is null");
}
} else {
Log.d("Product List", "Products list is empty");
}
}
}
}
PriceSort：
public class PriceSort implements Comparator<Products> {
public int compare(Products a, Products b) {
return a.getPrice().compareTo(b.getPrice());
}
}
答案 0 :(得分：0)
创建Comparator并在用户选择排序类型后调用Collections.sort(productsList, yourComparator)。并为适配器调用notifyDataSetChanged()。
这是可能的比较器
public class MyComparator implements Comparator<Product>
{
public int compare(Product p1, Product p2)
{
return c1.price.compareTo(c2.price);
}
}