Android check null or empty string in Android

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("TAG", 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.

From @Jon Skeet comment, really the String value is "null". Following code solved it

if (userEmail != null && !userEmail.isEmpty() && !userEmail.equals("null")) 

Yo can check it with this:

if(userEmail != null && !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())