How to handle null string in java -

i .net programmer , new in java. facing problem in handling null string in java. assigning value string array string variable completeddate. tried didn't work.

string completedate; completedate = country[23];  if(country[23] == null && country[23].length() == 0)  {     // ... }  if (completedate.equals("null"))  {     // ... }  if(completedate== null) {     // ... }  if(completedate == null || completedate.equals("null")) {     // ... } 

for starters...the safest way compare string against potentially null value put guaranteed not-null string first, , call .equals on that:

if("constantstring".equals(completeddate)) {     // logic } 

but in general, approach isn't correct.

the first one, commented, generate nullpointerexception it's evaluated past country[23] == null. if it's null, doesn't have .length property. meant call country[23] != null instead.

the second approach compares against literal string "null", may or may not true given scope of program. also, if completeddate null, fail - in case, rectify described above.

your third approach correct in sense it's thing checking against null. typically though, want logic if object wanted wasn't null.

your fourth approach correct accident; if completeddate null, or short-circuit. true if completeddate equal literal "null".