很抱歉格式化很奇怪;我不知道如何在这里格式化，这是我的第一个问题。
如果我直接从我的onCreate（）调用方法accessDatabase（），但是一旦我尝试使用异步任务，我无法使其工作，它可以正常工作，它当前形成的应用程序只是崩溃。当我没有崩溃时，它仍然不显示accessDatabase（）应该具有的信息。
任何建议表示赞赏。
package com.example.packagetrackingsystem;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.concurrent.ExecutionException;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.location.Address;
import android.location.Geocoder;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Parcelable;
import android.provider.Settings;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
/**
* An activity that displays a valid package id's locations.
* Allows for user to click a button to go into map view.
* @author kr
*
*/
public class PackageTextView extends Activity {
//String url2;
//JSONParser jsonParser = new JSONParser();
static JSONReader jr = new JSONReader();
static JSONReader jr2 = new JSONReader();
static JSONReader jr3 = new JSONReader();
String[] sArr = new String[1];
private String jsonResult, jsonResult2, jsonResult3;
static String locationsUrl = "http://ptsuwgb.comxa.com/ptsdbs4/get_all_locations.php";
static String packagesUrl = "http://ptsuwgb.comxa.com/ptsdbs4/get_all_packages.php";
static String customersUrl = "http://ptsuwgb.comxa.com/ptsdbs4/get_all_customers.php";
final static int LOCATIONS = 1;
final static int PACKAGES = 2;
final static int CUSTOMERS = 3;
private MapLocations mapLocation = new MapLocations();
private String packageId;
private ListView listViewLocations;
TextView textViewTest, textViewDateOfShipment;
Button buttonMapView;
private ArrayList<String> locationStrings = new ArrayList<String>();
private ArrayList<JSONObject> locationsArrayList = new ArrayList<JSONObject>();
private ArrayList<JSONObject> packagesArrayList = new ArrayList<JSONObject>();
private ArrayList<JSONObject> customersArrayList = new ArrayList<JSONObject>();
//ArrayList<JSONObject> packageActivity = new ArrayList<JSONObject>();
/**
* Sets content view, button, and views.
* Displays package statuses.
* Generates a Location object for map view.
* @param savedInstanceState
*/
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.package_text_view);
textViewTest = (TextView)findViewById(R.id.textViewTest);
textViewDateOfShipment = (TextView)findViewById(R.id.textViewDateOfShipment);
listViewLocations = (ListView) findViewById(R.id.listViewLocations);
buttonMapView = (Button)findViewById(R.id.buttonMapView);
Bundle extras = getIntent().getExtras();
if (extras != null) {
packageId = extras.getString("PACKAGE_ID");
}
else
textViewTest.setText("null");
//accessDatabase(locationsUrl, LOCATIONS, jr);
//accessDatabase(packagesUrl, PACKAGES, jr2);
//accessDatabase(customersUrl, CUSTOMERS, jr3);
DisplayAsyncTask dat = new DisplayAsyncTask();
dat.execute();
createLocation(locationsArrayList, packagesArrayList, customersArrayList);
//Toast.makeText(this, "Your information has been retieved.", Toast.LENGTH_LONG).show();
buttonMapView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Class ourClass;
try {
Bundle extras = new Bundle();
extras.putParcelable("MAP_LOCATION", mapLocation);
ourClass = Class.forName("com.example.packagetrackingsystem.MainMapActivity");
Intent ourIntent = new Intent(PackageTextView.this, ourClass);
ourIntent.putExtras(extras);
textViewTest.setText(mapLocation.getLocation(mapLocation.getLength() - 1) + "");
//ourIntent.putExtra("MAP_LOCATION", mapLocation);
//startActivity(ourIntent);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
private class DisplayAsyncTask extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
Toast.makeText(PackageTextView.this, "Your info is being retieved.", Toast.LENGTH_LONG).show();
}
@Override
protected Void doInBackground(Void... params) {
PackageTextView.this.accessDatabase(locationsUrl, LOCATIONS, jr);
PackageTextView.this.accessDatabase(packagesUrl, PACKAGES, jr2);
PackageTextView.this.accessDatabase(customersUrl, CUSTOMERS, jr3);
return null;
}
protected void onPostExec() {
//Toast.makeText(PackageTextView.this, "Your information has been retieved.", Toast.LENGTH_LONG).show();
}
}
/**
* Fills mapLocation with data.
* @param locList The locations for the package.
* @param packList The list to link the location with a customer
* @param custList The list of customers to look through and find correct customer for a package.
*/
private void createLocation(ArrayList<JSONObject> locList, ArrayList<JSONObject> packList, ArrayList<JSONObject> custList) {
// we don't want to display a checked out status on map since a check in would already have been shown
for(int i = 0; i < locList.size(); i++) {
if(!(locList.get(i).optString("Status").equals("CHECKEDOUT")))
mapLocation.addToArray(locList.get(i));
}
// getting customer id
int custId = 0;
for(int i = 0; i < packList.size(); i++) {
JSONObject jObj = packList.get(i);
if(jObj.optInt("PackageId") == Integer.parseInt(packageId)) {
custId = jObj.optInt("CustomerId");
}
}
String street = null;
String city = null;
String state = null;
String zipCode = null;
// getting address of correct customer, this represents final destination
for(int i = 0; i < custList.size(); i++) {
JSONObject jObj = custList.get(i);
if(jObj.optInt("CustomerId") == custId) {
street = jObj.optString("Street");
city = jObj.optString("City");
state = jObj.optString("State");
zipCode = jObj.optString("ZipCode");
}
}
String address = street + " " + city + " " + state + " " + zipCode;
// getting latitude and longitude from address of customer
Geocoder geoC = new Geocoder(PackageTextView.this.getApplicationContext(), Locale.getDefault());
List<Address> addresses = null;
try {
addresses = geoC.getFromLocationName(address, 1);
} catch (IOException e) {
e.printStackTrace();
}
Address location = addresses.get(0);
double latitude = location.getLatitude();
double longitude = location.getLongitude();
mapLocation.setFinalDestination(latitude, longitude);
}
/**
* Accesses certain parts of the database depending on parameters.
* @param url the url of the php file
* @param entity the table of the database to access
* @param jReader the JSONReader to use
*/
private void accessDatabase(String url, int entity, JSONReader jReader) {
try {
jsonResult = jReader.execute(new String[] { url }).get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
if(entity == LOCATIONS)
showAddressText();
else if(entity == PACKAGES)
getAllPackages();
else if(entity == CUSTOMERS)
getAllCustomers();
}
/**
* Gets all customers from the Customer table in database.
* Adds them to an ArrayList.
*/
private void getAllCustomers() {
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonCustomersArray = jsonResponse.optJSONArray("Customer");
for(int i = 0; i < jsonCustomersArray.length(); i++) {
JSONObject jsonCustomer = jsonCustomersArray.getJSONObject(i);
customersArrayList.add(jsonCustomer);
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
}
/**
* Gets all packages from the Package table in the database.
* Adds them to an ArrayList.
*/
private void getAllPackages() {
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonPackagesArray = jsonResponse.optJSONArray("Package");
for(int i = 0; i < jsonPackagesArray.length(); i++) {
JSONObject jsonPackage = jsonPackagesArray.getJSONObject(i);
packagesArrayList.add(jsonPackage);
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
}
/**
* Displays the correct locations based on packageId given.
* Fills an ArrayList with those locations.
*/
public void showAddressText() {
String dateTime = null;
String status = null;
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonLocationsArray = jsonResponse.optJSONArray("Location");
int currentLocationIndex = jsonLocationsArray.length() - 1;
for(int i = 0; i < jsonLocationsArray.length(); i++) {
JSONObject jsonLocation = jsonLocationsArray.getJSONObject(i);
if(jsonLocation.optInt("PackageId") == Integer.parseInt(packageId)) {
//packageActivity.add(jsonLocation);
locationsArrayList.add(jsonLocation);
String address = convertCoordsToAddress(jsonLocation);
dateTime = jsonLocation.optString("DateTime");
status = jsonLocation.optString("Status");
locationStrings.add(status + "\n" + address + "\n\t" + dateTime);;
}
}
if(locationStrings.isEmpty())
locationStrings.add("Id not valid");
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(
this,
android.R.layout.simple_list_item_1,
locationStrings );
listViewLocations.setAdapter(arrayAdapter);
}
/**
* Converts a JSONObject's latitude and longitude to readable address form.
* @param jsonChildNode The JSONObject to use.
* @return address the address generated from the JSONObject's information.
*/
private String convertCoordsToAddress(JSONObject jsonChildNode) {
String address = "";
Geocoder geoC = new Geocoder(PackageTextView.this.getApplicationContext(), Locale.getDefault());
List<Address> addresses = null;
double latitude = jsonChildNode.optDouble("Latitude");
double longitude = jsonChildNode.optDouble("Longitude");
try {
addresses = geoC.getFromLocation(latitude, longitude, 1);
} catch (IOException e) {
Log.e("LocationSampleActivity",
"IO Exception in getFromLocation()");
e.printStackTrace();
}
address += "\t" + addresses.get(0).getAddressLine(0) + "\n\t";
address += addresses.get(0).getAddressLine(1);
return address;
}
}
logcat的：
04-23 13:49:23.931: I/Adreno200-EGLSUB(13199): <ConfigWindowMatch:2081>: Format RGBA_8888.
04-23 13:49:23.951: D/memalloc(13199): /dev/pmem: Mapped buffer base:0x50ac3000 size:6733824 offset:6119424 fd:54
04-23 13:49:24.041: D/memalloc(13199): /dev/pmem: Mapped buffer base:0x512c3000 size:4890624 offset:4276224 fd:57
04-23 13:49:25.552: D/memalloc(13199): /dev/pmem: Mapped buffer base:0x5186d000 size:3129344 offset:2514944 fd:60
04-23 13:49:25.682: I/Adreno200-EGLSUB(13199): <ConfigWindowMatch:2081>: Format RGBA_8888.
04-23 13:49:25.692: D/memalloc(13199): /dev/pmem: Mapped buffer base:0x51c6f000 size:5505024 offset:4890624 fd:63
04-23 13:49:25.743: D/memalloc(13199): /dev/pmem: Mapped buffer base:0x521f4000 size:6119424 offset:5505024 fd:69
04-23 13:49:25.763: D/memalloc(13199): /dev/pmem: Unmapping buffer base:0x50ac3000 size:6733824 offset:6119424
04-23 13:49:25.763: D/memalloc(13199): /dev/pmem: Unmapping buffer base:0x512c3000 size:4890624 offset:4276224
04-23 13:49:25.763: D/memalloc(13199): /dev/pmem: Unmapping buffer base:0x5186d000 size:3129344 offset:2514944
04-23 13:49:26.203: D/memalloc(13199): /dev/pmem: Mapped buffer base:0x50ac3000 size:3129344 offset:2514944 fd:54
04-23 13:49:28.735: W/dalvikvm(13199): threadid=1: thread exiting with uncaught exception (group=0x40a6e1f8)
04-23 13:49:28.745: E/AndroidRuntime(13199): FATAL EXCEPTION: main
04-23 13:49:28.745: E/AndroidRuntime(13199): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.packagetrackingsystem/com.example.packagetrackingsystem.PackageTextView}: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.ActivityThread.access$600(ActivityThread.java:123)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.os.Handler.dispatchMessage(Handler.java:99)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.os.Looper.loop(Looper.java:137)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.ActivityThread.main(ActivityThread.java:4424)
04-23 13:49:28.745: E/AndroidRuntime(13199): at java.lang.reflect.Method.invokeNative(Native Method)
04-23 13:49:28.745: E/AndroidRuntime(13199): at java.lang.reflect.Method.invoke(Method.java:511)
04-23 13:49:28.745: E/AndroidRuntime(13199): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:812)
04-23 13:49:28.745: E/AndroidRuntime(13199): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:579)
04-23 13:49:28.745: E/AndroidRuntime(13199): at dalvik.system.NativeStart.main(Native Method)
04-23 13:49:28.745: E/AndroidRuntime(13199): Caused by: java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
04-23 13:49:28.745: E/AndroidRuntime(13199): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
04-23 13:49:28.745: E/AndroidRuntime(13199): at java.util.ArrayList.get(ArrayList.java:304)
04-23 13:49:28.745: E/AndroidRuntime(13199): at com.example.packagetrackingsystem.PackageTextView.createLocation(PackageTextView.java:199)
04-23 13:49:28.745: E/AndroidRuntime(13199): at com.example.packagetrackingsystem.PackageTextView.onCreate(PackageTextView.java:98)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.Activity.performCreate(Activity.java:4465)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
04-23 13:49:28.745: E/AndroidRuntime(13199): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
04-23 13:49:28.745: E/AndroidRuntime(13199): ... 11 more
不确定如何获得......还有11个。
答案 0 :(得分：3)
当您致电dat.execute()时，它不会立即运行。
首先，onPreExecute()函数将在主线程上执行。所以它会在你的onCreate()活动之后执行。
然后，doInBackground()函数将在另一个线程中运行。完成后，onPostExecute()将在主线程上执行。
因此，您不应在createLocation()之后致电dat.execute()。那时，还没有提取数据。您应该在onPostExecute()。
顺便说一下，它是onPostExecute()，而不是onPostExec()。