Android 列表视图无法正常工作？
Android Listview not working properly?
我最近一直在使用教程为我的 android 应用程序开发 CRUD 操作。 类 没有错误，应用程序与我的本地主机同步。但是，当我想单击一个按钮来查看我的所有用户配置文件时，我得到一个空白屏幕，但我的 logCat 显示一条成功消息？
请帮忙！
Class 控制查看：
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class AllProfile extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> profileList;
// url to get all products list
private static String url_all_profile = "http://MYIPADDRESS:8888/android_connect/get_all_profiles.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_USERPROFILE = "userprofile";
private static final String TAG_PID = "pid";
private static final String TAG_FIRSTNAME = "firstname";
// products JSONArray
JSONArray userprofile = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_profile);
// Hashmap for ListView
profileList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProfile().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(),
EditProfile.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 LoadAllProfile extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllProfile.this);
pDialog.setMessage("Loading profiles. 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_profile, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Profiles: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
userprofile = json.getJSONArray(TAG_USERPROFILE);
// looping through All Products
for (int i = 0; i < userprofile.length(); i++) {
JSONObject c = userprofile.getJSONObject(i);
// Storing each json item in variable
String pid = c.getString(TAG_PID);
String firstname = c.getString(TAG_FIRSTNAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, pid);
map.put(TAG_FIRSTNAME, firstname);
// adding HashList to ArrayList
profileList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
AddProfile.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(
AllProfile.this, profileList,
R.layout.list_item, new String[] { TAG_PID,
TAG_FIRSTNAME},
new int[] { R.id.pid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}
}
我的 php 正在运行，因为我已经调试它并在 HTML 上对其进行了测试，它显示了我想要的内容。
logCAT:
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme D/All Profiles:﹕ {"success":1,"UserProfile":[{"updated_at":"0000-00-00 00:00:00","address":"Tottenham Hale","age":"21","created_at":"2015-02-04 21:22:09","gender":"Male","lastname":"Sharma","pid":"4","firstname":"Ankhit","comments":"Help Me"}]}
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ org.json.JSONException: No value for userprofile
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at org.json.JSONObject.get(JSONObject.java:354)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at org.json.JSONObject.getJSONArray(JSONObject.java:544)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at com.example.ankhit.saveme.AllProfile$LoadAllProfile.doInBackground(AllProfile.java:144)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at com.example.ankhit.saveme.AllProfile$LoadAllProfile.doInBackground(AllProfile.java:110)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at android.os.AsyncTask.call(AsyncTask.java:287)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.util.concurrent.FutureTask.run(FutureTask.java:234)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at android.os.AsyncTask$SerialExecutor.run(AsyncTask.java:230)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.lang.Thread.run(Thread.java:856)
02-04 22:11:59.199 20039-20039/com.example.ankhit.saveme D/AbsListView﹕ unregisterIRListener() is called
02-04 22:11:59.199 20039-20039/com.example.ankhit.saveme D/AbsListView﹕ unregisterIRListener() is called
02-04 22:11:59.209 20039-20039/com.example.ankhit.saveme E/ViewRootImpl﹕ sendUserActionEvent() mView == null
我的列表视图文件没有错误。 add_profile 有一个带有 id/list 的列表视图，list_item 有两个分别带有 id/pid 和 id/name 的文本视图。有什么想法吗？
你需要改变这个：
private static final String TAG_USERPROFILE = "userprofile";
至
private static final String TAG_USERPROFILE = "UserProfile";
您没有正确解析 JSON。
"UserProfile" != "userprofile"
要从 JSON 中获取值，您必须使用适当的键。因为您使用了不正确的键，所以 org.json.JSONException 被抛出，并且大多数时候，您应该注意抛出的异常。 :)
我最近一直在使用教程为我的 android 应用程序开发 CRUD 操作。 类 没有错误，应用程序与我的本地主机同步。但是，当我想单击一个按钮来查看我的所有用户配置文件时，我得到一个空白屏幕，但我的 logCat 显示一条成功消息？
请帮忙！
Class 控制查看：
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
public class AllProfile extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> profileList;
// url to get all products list
private static String url_all_profile = "http://MYIPADDRESS:8888/android_connect/get_all_profiles.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_USERPROFILE = "userprofile";
private static final String TAG_PID = "pid";
private static final String TAG_FIRSTNAME = "firstname";
// products JSONArray
JSONArray userprofile = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_profile);
// Hashmap for ListView
profileList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
new LoadAllProfile().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(),
EditProfile.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 LoadAllProfile extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllProfile.this);
pDialog.setMessage("Loading profiles. 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_profile, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Profiles: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
userprofile = json.getJSONArray(TAG_USERPROFILE);
// looping through All Products
for (int i = 0; i < userprofile.length(); i++) {
JSONObject c = userprofile.getJSONObject(i);
// Storing each json item in variable
String pid = c.getString(TAG_PID);
String firstname = c.getString(TAG_FIRSTNAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, pid);
map.put(TAG_FIRSTNAME, firstname);
// adding HashList to ArrayList
profileList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
AddProfile.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(
AllProfile.this, profileList,
R.layout.list_item, new String[] { TAG_PID,
TAG_FIRSTNAME},
new int[] { R.id.pid, R.id.name });
// updating listview
setListAdapter(adapter);
}
});
}
}
}
我的 php 正在运行，因为我已经调试它并在 HTML 上对其进行了测试，它显示了我想要的内容。
logCAT:
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme D/All Profiles:﹕ {"success":1,"UserProfile":[{"updated_at":"0000-00-00 00:00:00","address":"Tottenham Hale","age":"21","created_at":"2015-02-04 21:22:09","gender":"Male","lastname":"Sharma","pid":"4","firstname":"Ankhit","comments":"Help Me"}]}
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ org.json.JSONException: No value for userprofile
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at org.json.JSONObject.get(JSONObject.java:354)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at org.json.JSONObject.getJSONArray(JSONObject.java:544)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at com.example.ankhit.saveme.AllProfile$LoadAllProfile.doInBackground(AllProfile.java:144)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at com.example.ankhit.saveme.AllProfile$LoadAllProfile.doInBackground(AllProfile.java:110)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at android.os.AsyncTask.call(AsyncTask.java:287)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.util.concurrent.FutureTask.run(FutureTask.java:234)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at android.os.AsyncTask$SerialExecutor.run(AsyncTask.java:230)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
02-04 22:11:59.189 20039-20371/com.example.ankhit.saveme W/System.err﹕ at java.lang.Thread.run(Thread.java:856)
02-04 22:11:59.199 20039-20039/com.example.ankhit.saveme D/AbsListView﹕ unregisterIRListener() is called
02-04 22:11:59.199 20039-20039/com.example.ankhit.saveme D/AbsListView﹕ unregisterIRListener() is called
02-04 22:11:59.209 20039-20039/com.example.ankhit.saveme E/ViewRootImpl﹕ sendUserActionEvent() mView == null
我的列表视图文件没有错误。 add_profile 有一个带有 id/list 的列表视图，list_item 有两个分别带有 id/pid 和 id/name 的文本视图。有什么想法吗？
你需要改变这个：
private static final String TAG_USERPROFILE = "userprofile";
至
private static final String TAG_USERPROFILE = "UserProfile";
您没有正确解析 JSON。
"UserProfile" != "userprofile"
要从 JSON 中获取值，您必须使用适当的键。因为您使用了不正确的键，所以 org.json.JSONException 被抛出，并且大多数时候，您应该注意抛出的异常。 :)