關閉應用程序如果沒有Internet連接

Question

我想關閉應用程序，如果沒有Internet連接可用。我知道有一個問題，我已經存在，但我做的完全一樣，似乎我的應用程序在註冊前工作正常，但在編輯暱稱字段中的文本後，它會拋出空指針錯誤，如果我在編輯文本後再次打開此處時執行此操作一起來看看：

我已經註冊了我的應用程序，並在抽屜裏我的綽號是可編輯的，所以我做這樣的：

pname = (EditText) findViewById(R.id.pname); 

     profimg.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       show(); 
      } 
     }); 

     pname.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       pname.setInputType(0x0000006); 
       pname.setCursorVisible(true); 

      } 
     }); 
     pname.setOnFocusChangeListener(new View.OnFocusChangeListener() { 
      @Override 
      public void onFocusChange(View v, boolean hasFocus) { 
       if(hasFocus){ 
        pname.setCursorVisible(false); 
       } 
       else{ 
        pname.setCursorVisible(false); 
       } 
      } 
     }); 

     pname.setOnEditorActionListener(new EditText.OnEditorActionListener() { 
      @Override 
      public boolean onEditorAction(TextView v, int actionId, KeyEvent event) { 
       if (event!=null && event.getKeyCode() != KeyEvent.KEYCODE_ENTER || actionId != EditorInfo.IME_ACTION_DONE) { 
        return false; 
       } 
       else if(actionId==EditorInfo.IME_ACTION_DONE || event==null || event.getKeyCode() == KeyEvent.KEYCODE_ENTER){ 

        pname.setCursorVisible(false); 
        InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE); 
        imm.hideSoftInputFromWindow(pname.getWindowToken(), 0); 
        return false; 
       } 
       return false; 
      } 
     }); 

pname.addTextChangedListener(new TextWatcher() { 
      @Override 
      public void beforeTextChanged(CharSequence s, int start, int count, int after) { 

      } 

      @Override 
      public void onTextChanged(CharSequence s, int start, int before, int count) { 

      } 

      @Override 
      public void afterTextChanged(Editable s) { 
       sp.edit().remove("personName").apply(); 
       name= s.toString(); 
       sp.edit().putString("personName",name).apply(); 
       try { 
        List<NameValuePair> params = new ArrayList<NameValuePair>(); 
        params.add(new BasicNameValuePair("nickname", name)); 
        params.add(new BasicNameValuePair("mobile", callNo)); 
        JSONObject json = jsonParser.makeHttpRequest(Config.URL_Info, "POST", 
          params); 
        int success = json.getInt(TAG_SUCCESS); 
        if (success == 1) { 
         Log.d("Status Updated", json.getString(TAG_MESSAGE)); 
        } 
       } catch (JSONException e) { 
        e.printStackTrace(); 
       } 

      } 
     }); 
     if(path1) { 
      String value = sp.getString("personName", name); 
      pname.setText(value); 
     } 

的錯誤是我在哪裏設置文本。我正在檢查setcontentview（佈局）後的起始連接可用性，並且該函數剛好在onCreate方法之後。

錯誤日誌：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int org.json.JSONObject.getInt(java.lang.String)' on a null object reference                    
                      at .afterTextChanged(PlaceCallActivity.java:206) 
                      at android.widget.TextView.sendAfterTextChanged(TextView.java:7942) 
                      at android.widget.TextView.setText(TextView.java:4079) 
                      at android.widget.TextView.setText(TextView.java:3928) 
                      at 

Answer 1

你需要檢查是否json變量是null或不

只有json變量不爲空繼續進一步的步驟

@Override 
     public void afterTextChanged(Editable s) { 
      sp.edit().remove("personName").apply(); 
      name= s.toString(); 
      sp.edit().putString("personName",name).apply(); 
      try { 
       List<NameValuePair> params = new ArrayList<NameValuePair>(); 
       params.add(new BasicNameValuePair("nickname", name)); 
       params.add(new BasicNameValuePair("mobile", callNo)); 
       JSONObject json = jsonParser.makeHttpRequest(Config.URL_Info, "POST", 
         params); 
       if(json!=null){ 
       int success = json.getInt(TAG_SUCCESS); 
       if (success == 1) { 
        Log.d("Status Updated", json.getString(TAG_MESSAGE)); 
       } 
       } 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 

     } 
    }); 

Answer 2

這是因爲jsonParser.makeHttpRequest(Config.URL_Info, "POST",params);是返回null！

因此，

int success = json.getInt(TAG_SUCCESS); 

是給java.lang.NullPointerException:

Answer 3

看起來你的JSON對象爲空

檢查，用前不爲空它

if(json != null){ 
    int success = json.getInt(TAG_SUCCESS); 
} 
else{ 
    Log.d("JSON", "NULL"); 
} 

Answer 4

你應該檢查網絡是否可用撥打電話到httprequest

嘗試在此之前，

public static boolean isNetworkAvailable(Activity activity) { 
    int[] networkTypes = {ConnectivityManager.TYPE_MOBILE, 
      ConnectivityManager.TYPE_WIFI}; 
    try { 
     ConnectivityManager connectivityManager = 
       (ConnectivityManager) activity.getSystemService(Context.CONNECTIVITY_SERVICE); 
     for (int networkType : networkTypes) { 
      NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo(); 
      if (activeNetworkInfo != null && 
        activeNetworkInfo.getType() == networkType) 
       return true; 
     } 
    } catch (Exception e) { 
     return false; 
    } 
    return false; 
} 

檢查Internet之前：

if(isNetworkAvailable(Mainactivity.this) 
    JSONObject json = jParser.makeHttpRequest(Config.URL_Info, "POST", 
         params); 

       try { 
        // Checking for SUCCESS TAG 
        if(json!=null){ 
        Log.d("RESPONSE ", json.toString()); 
        int success = json.getInt(TAG_SUCCESS); 

        if (success == 1) { 

        } else { 

        } 
       }else{ 


       } catch (JSONException e) { 
        e.printStackTrace(); 
       }