Android 如何将ListView放入自定义顺序?
我正在创建一个从服务器加载数据的列表视图! 如何根据变量的值(例如double)对列表进行排序? 为了帮助你更多,该应用程序计算设备之间的距离,我希望列表从最小到最大的距离开始!这是我的密码,有什么想法吗Android 如何将ListView放入自定义顺序?,android,Android,我正在创建一个从服务器加载数据的列表视图! 如何根据变量的值(例如double)对列表进行排序? 为了帮助你更多,该应用程序计算设备之间的距离,我希望列表从最小到最大的距离开始!这是我的密码,有什么想法吗 public class DriversList extends ListActivity{ private ProgressDialog pDialog; JSONParser jParser = new JSONParser(); ArrayList<HashMap<St
public class DriversList extends ListActivity{
private ProgressDialog pDialog;
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> driversList;
private static String url_all_drivers = "http://192.168.2.4/drivers/get_all_drivers.php";//192.168.2.4 , 10.0.2.2 , taxidroid.yzi.me
private static final String TAG_SUCCESS = "success";
private static final String TAG_DRIVERSID = "drivers";
private static final String TAG_ID = "id";
private static final String TAG_EMAIL="email";
private static final String TAG_NAME = "name";
private static final String TAG_SURNAME="surname";
private static final String TAG_TELEPHONE="telephone";
private static final String TAG_PLATE="plate";
private static final String TAG_CARMODEL="carmodel";
private static final String TAG_LATITUDE="latitude";
private static final String TAG_LONTITUDE="lontitude";
private static final String TAG_AVAILABLE="available";
private static final String DISTANCE="distance";
private static final String MILL="hh";
private double Clat,Clon;
JSONArray drivers = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.drivers_list_layout);
driversList=new ArrayList<HashMap<String,String>>();
new LoadAllDrivers().execute();
Clat=getIntent().getExtras().getDouble("ClLat");
Clon=getIntent().getExtras().getDouble("ClLon");
Toast.makeText(getBaseContext(), ""+Clat+""+Clon, Toast.LENGTH_LONG).show();
}
class LoadAllDrivers extends AsyncTask<String, String, String>{
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(DriversList.this);
pDialog.setMessage("Loading products. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();}
@Override
protected String doInBackground(String... args) {
List<NameValuePair> params = new ArrayList<NameValuePair>();
JSONObject json = jParser.makeHttpRequest(url_all_drivers, "GET", params);
Log.d("All Drivers: ", json.toString());
try {
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
drivers = json.getJSONArray(TAG_DRIVERSID);
for (int i = 0; i < drivers.length(); i++) {
JSONObject c = drivers.getJSONObject(i);
String id = c.getString(TAG_ID);
String email=c.getString(TAG_EMAIL);
String name = c.getString(TAG_NAME);
String surname=c.getString(TAG_SURNAME);
String telephone=c.getString(TAG_TELEPHONE);
String plate=c.getString(TAG_PLATE);
String carmodel=c.getString(TAG_CARMODEL);
double lat=c.getDouble(TAG_LATITUDE);
double lon=c.getDouble(TAG_LONTITUDE);
String avail=c.getString(TAG_AVAILABLE);
double R = 6371; // earth’s radius (mean radius = 6,371km)
double dLat = Math.toRadians(Clat-lat);
double dLon = Math.toRadians(Clon-lon);
double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(Math.toRadians(Clat)) * Math.cos(Math.toRadians(lat)) *
Math.sin(dLon/2) * Math.sin(dLon/2);
double c1 = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
double d = R * c1;
double gg=d*1000;
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_ID, id);
map.put(TAG_NAME, name);
map.put(TAG_SURNAME, surname);
map.put(TAG_CARMODEL, carmodel);
if (d<1) {map.put(DISTANCE,String.format("%.2f", gg)); map.put(MILL, "m"); }
else {map.put(DISTANCE, String.format("%.2f", d)); map.put(MILL, "km"); }
driversList.add(map);
}
} else {runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(DriversList.this,"Αυτη τη στιγμη δεν υπαρχει διαθεσιμος οδηγος",Toast.LENGTH_SHORT).show();}});
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String file_url) {
pDialog.dismiss();
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
DriversList.this, driversList,
R.layout.list_item, new String[] { TAG_ID,
TAG_NAME,TAG_SURNAME,TAG_CARMODEL,DISTANCE,MILL},
new int[] { R.id.id, R.id.name,R.id.surname,R.id.carmodel,R.id.txtdistance1,R.id.txtmorkm});
setListAdapter(adapter);
}
});
}
}
}
公共类驱动程序列表扩展了ListActivity{
私人对话;
JSONParser jParser=新的JSONParser();
ArrayList驱动列表;
专用静态字符串url\u所有\u驱动程序=”http://192.168.2.4/drivers/get_all_drivers.php“;//192.168.2.4,10.0.2.2,taxidroid.yzi.me
私有静态最终字符串标记_SUCCESS=“SUCCESS”;
私有静态最终字符串标记_DRIVERSID=“drivers”;
私有静态最终字符串标记\u ID=“ID”;
私有静态最终字符串标记\u EMAIL=“EMAIL”;
私有静态最终字符串标记_NAME=“NAME”;
私有静态最终字符串标记_姓氏=“姓氏”;
专用静态最终字符串标记_TELEPHONE=“TELEPHONE”;
专用静态最终字符串标签\u PLATE=“PLATE”;
私有静态最终字符串标记\u CARMODEL=“CARMODEL”;
私有静态最终字符串标记_LATITUDE=“LATITUDE”;
私有静态最终字符串标记_LONTITUDE=“LONTITUDE”;
私有静态最终字符串标记_AVAILABLE=“AVAILABLE”;
私有静态最终字符串距离=“距离”;
专用静态终轧管磨机=“hh”;
二等兵,克隆;
JSONArray驱动程序=null;
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
requestWindowFeature(窗口。功能\u无\u标题);
setContentView(R.layout.drivers\u list\u布局);
driversList=newarraylist();
新建LoadAllDrivers().execute();
Clat=getIntent().getExtras().getDouble(“ClLat”);
Clon=getIntent().getExtras().getDouble(“ClLon”);
Toast.makeText(getBaseContext(),“”+Clat+“”+Clon,Toast.LENGTH_LONG).show();
}
类LoadAllDrivers扩展了AsyncTask{
@凌驾
受保护的void onPreExecute(){
super.onPreExecute();
pDialog=newprogressdialog(DriversList.this);
pDialog.setMessage(“正在加载产品。请稍候…”);
pDialog.setUndeterminate(假);
pDialog.setCancelable(假);
pDialog.show();}
@凌驾
受保护的字符串doInBackground(字符串…args){
List params=new ArrayList();
JSONObject json=jParser.makeHttpRequest(url_all_驱动程序,“GET”,参数);
Log.d(“所有驱动程序:,json.toString());
试一试{
int success=json.getInt(TAG_success);
如果(成功==1){
drivers=json.getJSONArray(TAG_DRIVERSID);
对于(int i=0;i 如果(d您应该对ListView适配器进行子类化。这里创建一个排序函数。任何排序算法都应该这样做。然后将您的项目添加到适配器,对它们进行排序,最后将适配器设置到ListView。ListView与否在这里并不重要。您应该做的只是在将数据处理到ListView之前对数据进行排序。首先,为什么不创建一个类来表示驱动程序数据,而不是使用HashMap
无论如何,您要寻找的可以通过使用来完成,您需要做的是:
- 创建一个实现接口的类
public class DriverComparator implements Comparator<HashMap<String, String>> {
public int compare(HashMap<String, String> o1,
HashMap<String, String> o2) {
double distance1 = -1;
double distance2 = -1;
try {
distance1 = Double.parseDouble(o1.get("DISTANCE"));
} catch (NumberFormatException ex){
} catch (NullPointerException nex){
}
try {
distance2 = Double.parseDouble(o1.get("DISTANCE"));
} catch (NumberFormatException ex){
} catch (NullPointerException nex){
}
if (distance1 == distance2){
return 0;
}
if (distance1 > distance2) {
return 1;
}
return -1;
}
这是一个关于比较器的好教程:在插入listview之前,您需要对数据进行排序。谢谢您的帮助!我如何创建一个类而不是HashMap?这样做的好处是什么?可能是个愚蠢的问题,但我在开发方面是新手。以及
Collections.sort(list, new DriverComparator());