2016-01-13 69 views
-2

我知道這是一個非常常見的話題,但我得到這個錯誤,不知道爲什麼。該代碼在Eclipse中運行得非常好,但在Studio中按下按鈕時會崩潰。我可以想到的唯一區別是Request.Method而不是像Eclipse中的Method。之前我認爲它是因爲edittext的值沒有得到。但它顯示在吐司。爲什麼它顯示nullpointerexception?

Error 
 

 
01-13 11:13:34.242 14427-14427/com.sam.sports E/AndroidRuntime: FATAL EXCEPTION: main 
 
Process: com.sam.sports, PID: 14427 
 
java.lang.NullPointerException 
 
at com.sam.sports.LoginPage.checkLogin(LoginPage.java:180) 
 
at com.sam.sports.LoginPage.access$200(LoginPage.java:28) 
 
at com.sam.sports.LoginPage$1.onClick(LoginPage.java:80) 
 
at android.view.View.performClick(View.java:4562) 
 
at android.view.View$PerformClick.run(View.java:18918) 
 
at android.os.Handler.handleCallback(Handler.java:808) 
 
at android.os.Handler.dispatchMessage(Handler.java:103) 
 
at android.os.Looper.loop(Looper.java:193) 
 
at android.app.ActivityThread.main(ActivityThread.java:5388) 
 
at java.lang.reflect.Method.invokeNative(Native Method) 
 
at java.lang.reflect.Method.invoke(Method.java:515) 
 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:655) 
 
at dalvik.system.NativeStart.main(Native Method) 
 
01-13 11:13:38.996 14427-14427/com.sam.sports I/Process: Sending signal. PID: 14427 SIG: 9
public class LoginPage extends AppCompatActivity { 
 
    private static final String TAG = RegisterPage.class.getSimpleName(); 
 
    private Button btnLogin; 
 
    private Button btnLinkToRegister; 
 
    private EditText inputEmail; 
 
    private EditText inputPassword; 
 
    private ProgressDialog pDialog; 
 
    private SessionManager session; 
 
    private SQLiteHandler db; 
 

 
    String name; 
 

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

 
     inputEmail = (EditText) findViewById(R.id.email_login); 
 
     inputPassword = (EditText) findViewById(R.id.password_login); 
 
     btnLogin = (Button) findViewById(R.id.login_btn); 
 
     btnLinkToRegister = (Button) findViewById(R.id.btnLinktoRegd); 
 

 

 

 
     // Progress dialog 
 
     pDialog = new ProgressDialog(this); 
 
     pDialog.setCancelable(false); 
 

 
     // SQLite database handler 
 
     db = new SQLiteHandler(getApplicationContext()); 
 

 
     // Session manager 
 
     session = new SessionManager(getApplicationContext()); 
 

 
     // Check if user is already logged in or not 
 
     if (session.isLoggedIn()) { 
 
      // User is already logged in. Take him to main activity 
 
      Intent intent = new Intent(LoginPage.this, HomePage.class); 
 
      startActivity(intent); 
 
      finish(); 
 
     } 
 

 
     // Login button Click Event 
 
     btnLogin.setOnClickListener(new View.OnClickListener() { 
 

 
      public void onClick(View view) { 
 
       String email = inputEmail.getText().toString().trim(); 
 
       String password = inputPassword.getText().toString().trim(); 
 

 
       // Check for empty data in the form 
 
       if (!email.isEmpty() && !password.isEmpty()) { 
 
        // login user 
 
        checkLogin(email, password); 
 
        //Toast.makeText(getApplicationContext(), email + "\n" + password, Toast.LENGTH_LONG).show(); 
 
       } else { 
 
        // Prompt user to enter credentials 
 
        Toast.makeText(getApplicationContext(), "Please enter the credentials!", Toast.LENGTH_LONG).show(); 
 
       } 
 
      } 
 

 
     }); 
 

 
     // Link to Register Screen 
 
     btnLinkToRegister.setOnClickListener(new View.OnClickListener() { 
 

 
      public void onClick(View view) { 
 
       startActivity(new Intent(LoginPage.this, RegisterPage.class)); 
 
       finish(); 
 
      } 
 
     }); 
 

 
    } 
 

 
    /** 
 
    * function to verify login details in mysql db 
 
    * */ 
 
    private void checkLogin(final String email, final String password) { 
 
     // Tag used to cancel the request 
 
     String tag_string_req = "req_login"; 
 

 
     pDialog.setMessage("Logging in ..."); 
 
     showDialog(); 
 

 
     StringRequest strReq = new StringRequest(Request.Method.POST, 
 
       AppConfig.URL_LOGIN, new Response.Listener<String>() { 
 

 
      @Override 
 
      public void onResponse(String response) { 
 
       Log.d(TAG, "Login Response: " + response.toString()); 
 
       hideDialog(); 
 

 
       try { 
 
        JSONObject jObj = new JSONObject(response); 
 
        String status = jObj.getString("status"); 
 

 
        // Now check status value 
 
        if (status.equals("0")) { 
 

 
         Toast.makeText(getApplicationContext(), "Email or Password may be incorrect! Please try again.", Toast.LENGTH_LONG).show(); 
 

 
        }else if(status.equals("1")){ 
 
         // user successfully logged in 
 
         // Create login session 
 
         session.setLogin(true); 
 

 
         // Now store the user in SQLite 
 
         JSONObject userData = jObj.getJSONObject("userData"); 
 
         String uid = userData.getString("id"); 
 
         String name = userData.getString("name"); 
 
         String email = userData.getString("email"); 
 
         String created_at = userData.getString("created_at"); 
 

 
         // Inserting row in users table 
 
         db.addUser(name, email, uid, created_at); 
 

 
         // Launch main activity 
 
         startActivity(new Intent(LoginPage.this, HomePage.class)); 
 
         finish(); 
 
        } else { 
 
         // Error in login. Get the error message 
 
         String errorMsg = jObj.getString("error_msg"); 
 
         Toast.makeText(getApplicationContext(), errorMsg, Toast.LENGTH_LONG).show(); 
 
        } 
 
       } catch (JSONException e) { 
 
        // JSON error 
 
        e.printStackTrace(); 
 
        Toast.makeText(getApplicationContext(), "Json error: " + e.getMessage(), Toast.LENGTH_LONG).show(); 
 
       } 
 

 
      } 
 
     }, new Response.ErrorListener() { 
 

 
      @Override 
 
      public void onErrorResponse(VolleyError error) { 
 
       Log.e(TAG, "Login Error: " + error.getMessage()); 
 
       Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show(); 
 
       hideDialog(); 
 
      } 
 
     }) { 
 

 
      @Override 
 
      protected Map<String, String> getParams() { 
 
       // Posting parameters to login url 
 
       Map<String, String> params = new HashMap<String, String>(); 
 
       params.put("email", email); 
 
       params.put("password", password); 
 

 
       return params; 
 
      } 
 

 
     }; 
 

 
     // Adding request to request queue 
 
     AppController.getInstance().addToRequestQueue(strReq, tag_string_req); 
 
    } 
 

 
    private void showDialog() { 
 
     if (!pDialog.isShowing()) 
 
      pDialog.show(); 
 
    } 
 

 
    private void hideDialog() { 
 
     if (pDialog.isShowing()) 
 
      pDialog.dismiss(); 
 
    } 
 

 

 

 
}

+0

提及您在哪條線上獲得例外。 –

+0

其中'checkLogin(email,password);'在'btnLogin.setOnClickListener'中有' – Sam

+0

其中checkLogin方法? –

回答

0

雖然這不是你的問題的解決方案(用於解決下面看),重構的checkLogin方法將definetly幫助很多在發現錯誤的原因。由於事實上,checkLogin方法是很長的路要走,我已經將一些代碼移動到其他方法。

複製它,運行它並讓我們知道哪一行會引發錯誤。

/** 
* function to verify login details in mysql db 
* */ 
private void checkLogin(final String email, final String password) { 
    // Tag used to cancel the request 
    String tag_string_req = "req_login"; 
    pDialog.setMessage("Logging in ..."); 
    showDialog(); 

    StringRequest strReq = new StringRequest(Request.Method.POST, 
      AppConfig.URL_LOGIN, new Response.Listener<String>() { 

     @Override 
     public void onResponse(String response) { 
      Log.d(TAG, "Login Response: " + response.toString()); 
      hideDialog(); 
      checkStatus(); 
     } 
    }, new Response.ErrorListener() { 

     @Override 
     public void onErrorResponse(VolleyError error) { 
      Log.e(TAG, "Login Error: " + error.getMessage()); 
      Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show(); 
      hideDialog(); 
     } 
    }) { 

     @Override 
     protected Map<String, String> getParams() { 
      // Posting parameters to login url 
      Map<String, String> params = new HashMap<String, String>(); 
      params.put("email", email); 
      params.put("password", password); 

      return params; 
     } 

    }; 

    // Adding request to request queue 
    AppController.getInstance().addToRequestQueue(strReq, tag_string_req); 
} 

private void checkStatus() { 
    try { 
     JSONObject jObj = new JSONObject(response); 
     String status = jObj.getString("status"); 

     // Now check status value 
     if (status.equals("0")) { 
      processStatusZero(); 
     }else if(status.equals("1")){ 
      processStatusOne(jObj); 
     } else { 
      processStatusError(jObj); 
     } 
    } catch (JSONException e) { 
     // JSON error 
     e.printStackTrace(); 
     Toast.makeText(getApplicationContext(), "Json error: " + e.getMessage(), Toast.LENGTH_LONG).show(); 
    } 
} 

private void processStatusZero() { 
    Toast.makeText(getApplicationContext(), "Email or Password may be incorrect! Please try again.", Toast.LENGTH_LONG).show(); 
} 

private void processStatusOne(JSONObject jObj) { 
    // user successfully logged in 
    // Create login session 
    session.setLogin(true); 

    // Now store the user in SQLite 
    JSONObject userData = jObj.getJSONObject("userData"); 
    String uid = userData.getString("id"); 
    String name = userData.getString("name"); 
    String email = userData.getString("email"); 
    String created_at = userData.getString("created_at"); 

    // Inserting row in users table 
    db.addUser(name, email, uid, created_at); 

    // Launch main activity 
    startActivity(new Intent(LoginPage.this, HomePage.class)); 
    finish(); 
} 

private void processStatusError(JSONObject jObj) { 
    // Error in login. Get the error message 
    String errorMsg = jObj.getString("error_msg"); 
    Toast.makeText(getApplicationContext(), errorMsg, Toast.LENGTH_LONG).show(); 
} 

現在爲了實際的解決方案:您需要將AppControler添加到Android Manifest。您可以通過在您的清單文件中添加以下行做到這一點:

<application 
android:name=".AppController" 
android:allowBackup="true" 
android:icon="@drawable/ic_launcher" 
android:label="@string/app_name" 
android:theme="@style/AppTheme"> 

這樣AppController.getInstance()將停止返回null。