Error requesting a will string when passing a string with a null value as a parameter

Question

I use the following code to query a string on volley

pDialog = new ProgressDialog(context); pDialog.setMessage("Loading..."); pDialog.setCancelable(false); pDialog.show(); StringRequest strReq = new StringRequest(Method.POST, url, new Response.Listener<String>() { @Override public void onResponse(String response) { pDialog.dismiss(); Log.e(tag, response); } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { pDialog.dismiss(); } }) { protected Map<String, String> getParams(){ Map<String, String> params = new HashMap<String, String>(); params.put("tag", "SHOW_FILE"); params.put("filename",filename); return params; }; }; // Adding request to request queue Application.getInstance().addToRequestQueue(strReq, "get_file"); 

If the variable filename = null, I get the following error:

 08-02 10:28:06.192: E/Volley(2935): [2128] NetworkDispatcher.run: Unhandled exception java.lang.NullPointerException 08-02 10:28:06.192: E/Volley(2935): java.lang.NullPointerException 08-02 10:28:06.192: E/Volley(2935): at libcore.net.UriCodec.encode(UriCodec.java:132) 08-02 10:28:06.192: E/Volley(2935): at java.net.URLEncoder.encode(URLEncoder.java:57) 08-02 10:28:06.192: E/Volley(2935): at com.android.volley.Request.encodeParameters(Request.java:449) 08-02 10:28:06.192: E/Volley(2935): at com.android.volley.Request.getBody(Request.java:435) 08-02 10:28:06.192: E/Volley(2935): at com.android.volley.toolbox.HurlStack.addBodyIfExists(HurlStack.java:236) 08-02 10:28:06.192: E/Volley(2935): at com.android.volley.toolbox.HurlStack.setConnectionParametersForRequest(HurlStack.java:210) 08-02 10:28:06.192: E/Volley(2935): at com.android.volley.toolbox.HurlStack.performRequest(HurlStack.java:106) 08-02 10:28:06.192: E/Volley(2935): at com.android.volley.toolbox.BasicNetwork.performRequest(BasicNetwork.java:93) 08-02 10:28:06.192: E/Volley(2935): at com.android.volley.NetworkDispatcher.run(NetworkDispatcher.java:110) 

Do I need to check the null value for all param i POST or any other methods to solve this problem and handle the null value?

Answer 1

Thanks to Giru Bhai for your help.

I created a new method to solve this problem, and the variable became zero

  protected Map<String, String> getParams(){ Map<String, String> params = new HashMap<String, String>(); params.put("key1", value1); params.put("key2",value2); params.put("key3",value3); return checkParams(params); }; private Map<String, String> checkParams(Map<String, String> map){ Iterator<Entry<String, String>> it = map.entrySet().iterator(); while (it.hasNext()) { Map.Entry<String, String> pairs = (Map.Entry<String, String>)it.next(); if(pairs.getValue()==null){ map.put(pairs.getKey(), ""); } } return map; } 

I think this is easier than checking all the values ​​before inserting them into the map

Answer 2

In the Volley Request Class, it calls the encodeParameters method, which is called by the getBody() method.

In the getBody() method, it checks all params as

  public byte[] getBody() throws AuthFailureError { Map<String, String> params = getParams(); if (params != null && params.size() > 0) { return encodeParameters(params, getParamsEncoding()); } return null; } 

but not for individual parameters. Thus, you need to check for null in individual parameters in the getParams() method, for example

  protected Map<String, String> getParams(){ Map<String, String> params = new HashMap<String, String>(); params.put("tag", "SHOW_FILE"); if(filename != null)params.put("filename",filename); return params; };