Android check null or empty string in Android

Question

In my trying AsyncTask I get email address from my server  In onPostExecute   I have to check is email address empty or null  I used following code to check it   if  userEmail    null  amp  amp   userEmail isEmpty          Toast makeText getActivity    userEmail  Toast LENGTH LONG  show        UserEmailLabel setText userEmail       But in my Toast I see null is printed  My full code   private class LoadPersonalData extends AsyncTask lt String  Void  Void gt         Override     protected void onPreExecute             super onPreExecute               protected Void doInBackground String    res            List lt NameValuePair gt  params   new ArrayList lt NameValuePair gt             params add new BasicNameValuePair  user id   PrefUserName            params add new BasicNameValuePair  type   type data            JSONObject json   jsonParser makeHttpRequest Url   POST   params           String result               try               result   json getString  message              catch  JSONException e                e printStackTrace                      if  result equals  success                  try                   userEmail   json getString  email                  catch  JSONException e                       TODO Auto-generated catch block                 e printStackTrace                                    return null              Override     protected void onPostExecute Void result               TODO Auto-generated method stub         super onPostExecute result                       if  userEmail    null  amp  amp   userEmail isEmpty                  Toast makeText getActivity    userEmail  Toast LENGTH LONG  show                UserEmailLabel setText userEmail                     How can I check for null and empty string

User · Answer

Incase all the answer given does not work  kindly try   String myString   null   if myString trim   equalsIgnoreCase  null           do something

User · Answer

All you can do is to call equals   method on empty String literal and pass the object you are testing as shown below     String nullString   null   String empty   new String     boolean test      equals empty      true   System out println test     boolean check      equals nullString      false   System out println check

User · Answer

if you check null or empty String so you can try this   if  createReminderRequest getDate      null  amp  amp  createReminderRequest getDate   trim   equals           DialogUtility showToast this  ProjectUtils getString R string please select date n time

User · Answer

Yo can check it with this   if userEmail    null  amp  amp   userEmail  isEmpty      And remember you must use from exact above code with that order  Because that ensuring you will not get a null pointer exception from userEmail isEmpty   if userEmail is null   Above description  it s only available since Java SE 1 6  Check userEmail length      0 on previous versions    UPDATE   Use from isEmpty stringVal  method from TextUtils class   if  TextUtils isEmpty userEmail     Kotlin   Use from isNullOrEmpty for null or empty values OR isNullOrBlank for null or empty or consists solely of whitespace characters   if  userEmail isNullOrEmpty        if  userEmail isNullOrBlank

User · Answer

From  Jon Skeet comment  really the String value is  null   Following code solved it  if  userEmail    null  amp  amp   userEmail isEmpty    amp  amp   userEmail equals  null

User · Answer

You can check it with utility method  isEmpty  from TextUtils   isEmpty CharSequence str  method check both condition  for null and length   public static boolean isEmpty CharSequence str         if  str    null    str length      0          return true       else         return false

User · Answer

Use TextUtils isEmpty  someString   String myString   null   if  TextUtils isEmpty myString         return     or break  continue  throw       myString is neither null nor empty if this point is reached Log i  quot TAG quot   myString    Notes  The documentation states that both null and zero length are checked for  No need to reinvent the wheel here  A good practice to follow is early return

User · Answer

My simple solution to test if a string is null   if  s equals  null                There are two cases   The variable  of type String  is null doesn t exists      works   The variable has a null value    equals  null   gives te right boolean value   See the picture

User · Answer

Checking for empty string if it is equal to null  length is zero or containing  null  string  public static boolean isEmptyString String text            return  text    null    text trim   equals  null      text trim                    length    lt   0

User · Answer

This worked for me  EditText   etname    EditText  findViewById R id etname    if etname length      0                       etname setError  Required field                     else                      Toast makeText getApplicationContext    Saved  Toast LENGTH LONG  show                        or Use this for strings  String DEP DATE  if  DEP DATE equals        DEP DATE length      0    DEP DATE isEmpty      DEP DATE    null

[android] Android check null or empty string in Android

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