Checking if a string is empty or null in Java [duplicate]

Question

I'm parsing HTML data. The String may be null or empty, when the word to parse does not match.

So, I wrote it like this:

if(string.equals(null) || string.equals("")){     Log.d("iftrue", "seem to be true"); }else{     Log.d("iffalse", "seem to be false"); } 

When I delete String.equals(""), it does not work correctly.

I thought String.equals("") wasn't correct.

How can I best check for an empty String?

Answer 1

Correct way to check for null or empty or string containing only spaces is like this:

if(str != null && !str.trim().isEmpty()) { /* do your stuffs here */ } 

Answer 2

You can leverage Apache Commons StringUtils.isEmpty(str), which checks for empty strings and handles null gracefully.

Example:

System.out.println(StringUtils.isEmpty("")); // true System.out.println(StringUtils.isEmpty(null)); // true 

Google Guava also provides a similar, probably easier-to-read method: Strings.isNullOrEmpty(str).

Example:

System.out.println(Strings.isNullOrEmpty("")); // true System.out.println(Strings.isNullOrEmpty(null)); // true