在textview上顯示jsonarray數據

Question

即時嘗試爲學校製作android應用程序。這是我想要發生的事情 首先，當用戶登錄的用戶名保存在共享首選項 秒，使用sharedpreference我將檢索數據庫中的用戶信息。 第三，解析數據並在textviews中顯示信息。 這是我的PHP文件

 <?php 



    /* 
    Our "config.inc.php" file connects to database every time we include or require 
    it within a php script. Since we want this script to add a new user to our db, 
    we will be talking with our database, and therefore, 
    let's require the connection to happen: 
    */ 
    require("config.inc.php"); 

    if (!empty($_POST)) { 

     //initial query 
     $query = "Select * FROM userinfo where username = :user"; 

     $query_params = array(':user' = > $_POST['username']); 

     //execute query 
     try { 
      $stmt = $db - > prepare($query); 
      $result = $stmt - > execute($query_params); 
     } catch (PDOException $ex) { 
      $response["success"] = 0; 
      $response["message"] = "Database Error!"; 
      die(json_encode($response)); 
     } 

     // Finally, we can retrieve all of the found rows into an array using fetchAll 
     $rows = $stmt - > fetchAll(); 

     if ($rows) { 
      $response["success"] = 1; 
      $response["message"] = "Post Available!"; 
      $response["users"] = array(); 

      foreach($rows as $row) { 
       $user = array(); 
       $user["username"] = $row["username"]; 
       $user["firstname"] = $row["firstname"]; 
       $user["middlename"] = $row["middlename"]; 
       $user["lastname"] = $row["lastname"]; 
       $user["course"] = $row["course"]; 

       //update our repsonse JSON data 
       array_push($response["users"], $user); 
      } 

      // echoing JSON response 
      echo json_encode($response); 

     } else { 
      $response["success"] = 0; 
      $response["message"] = "No user available!"; 
      die(json_encode($response)); 
     } 
    } else {} 
      ?> 

，這是我的java代碼

import java.util.ArrayList; 
    import java.util.List; 
    import org.apache.http.NameValuePair; 
    import org.apache.http.message.BasicNameValuePair; 
    import org.json.JSONArray; 
    import org.json.JSONException; 
    import org.json.JSONObject; 
    import android.app.Activity; 
    import android.app.ProgressDialog; 
    import android.content.SharedPreferences; 
    import android.os.AsyncTask; 
    import android.os.Bundle; 
    import android.preference.PreferenceManager; 
    import android.util.Log; 
    import android.widget.TextView; 

    public class ProfileActivity extends Activity { 
    // All xml labels 

    TextView txtFname; 
    TextView txtMname; 
    TextView txtLname; 

    // Progress Dialog 
    private ProgressDialog pDialog; 

    // Creating JSON Parser object 
    JSONParser jsonParser = new JSONParser(); 

    // Profile json object 
    JSONArray user; 
    JSONObject hay; 
    // Profile JSON url 
    private static final String PROFILE_URL =   "http://10.0.2.2/webservice1/userprofile.php"; 

    // ALL JSON node names 
    private static final String TAG_PROFILE = "user"; 
    // private static final String TAG_ID = "id"; 
    private static final String TAG_USERNAME = "username"; 
    private static final String TAG_FIRSTNAME = "firstname"; 
    private static final String TAG_MIDDLENAME = "middlename"; 
    private static final String TAG_LASTNAME = "lastname"; 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_profile); 


    txtFname = (TextView) findViewById(R.id.fname); 
    txtMname = (TextView) findViewById(R.id.mname); 
    txtLname = (TextView) findViewById(R.id.lname); 

    // Loading Profile in Background Thread 
    new LoadProfile().execute(); 
    } 

    /** 
    * Background Async Task to Load profile by making HTTP Request 
    * */ 
    class LoadProfile extends AsyncTask<String, String, String> { 

    /** 
    * Before starting background thread Show Progress Dialog 
    * */ 

    public void test(){ 

       /** 
       * Updating parsed JSON data into ListView 
       * */ 
       // Storing each json item in variable 
       try { 
        String firstname = hay.getString(TAG_FIRSTNAME); 
        String middlename = hay.getString(TAG_MIDDLENAME); 
        String lastname = hay.getString(TAG_LASTNAME); 

        // displaying all data in textview 

        txtEmail.setText("Email: " + firstname); 
        txtMobile.setText("Mobile: " + middlename); 
        txtAddress.setText("Add: " + lastname); 

       } catch (JSONException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
       } 

    } 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     pDialog = new ProgressDialog(ProfileActivity.this); 
     pDialog.setMessage("Loading profile ..."); 
     pDialog.setIndeterminate(false); 
     pDialog.setCancelable(false); 
     pDialog.show(); 
    } 
    /** 
    * getting Profile JSON 
    * */ 
    protected String doInBackground(String... args) { 
     // Building Parameters 

     SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(ProfileActivity.this); 
     String post_username = sp.getString("username", "anon"); 
     List<NameValuePair> params = new ArrayList<NameValuePair>(); 
     params.add(new BasicNameValuePair("username", post_username)); 
     // getting JSON string from URL 
     JSONObject json = jsonParser.makeHttpRequest(PROFILE_URL, "POST", 
       params); 

     // Check your log cat for JSON reponse 
     Log.d("Profile JSON: ", json.toString()); 

     try { 
      // profile json object 
      user = json.getJSONArray(TAG_PROFILE); 
     } 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 
     test(); 

    } 

} 
    } 

即時得到一個空指針異常ProfileActivity $ LoadProfile.test 請幫我我只是一個初學者

Answer 1

你有沒有初始化嘿。你剛剛宣佈了嘿。 如果您的數據在json中，則在postexecute中分配hey = json或直接傳遞json以在其中進行測試和使用。