How to check if my string is equal to null?

Question

if (myString != null && !myString.isEmpty()) {
  // doSomething
}

---

As further comment, you should be aware of this term in the equals contract:

From Object.equals(Object):

For any non-null reference value x, x.equals(null) should return false.

The way to compare with null is to use x == null and x != null.

Moreover, x.field and x.method() throws NullPointerException if x == null.

If myString is null, then calling myString.equals(null) or myString.equals("") will fail with a NullPointerException. You cannot call any instance methods on a null variable.

Check for null first like this:

if (myString != null && !myString.equals("")) {
    //do something
}

This makes use of short-circuit evaluation to not attempt the .equals if myString fails the null check.

Apache commons StringUtils.isNotEmpty is the best way to go.

If myString is in fact null, then any call to the reference will fail with a Null Pointer Exception (NPE). Since java 6, use #isEmpty instead of length check (in any case NEVER create a new empty String with the check).

if (myString != null &&  !myString.isEmpty()){
    doSomething();
}

Incidentally if comparing with String literals as you do, would reverse the statement so as not to have to have a null check, i.e,

if ("some string to check".equals(myString)){
  doSomething();
} 

instead of :

if (myString != null &&  myString.equals("some string to check")){
    doSomething();
}

WORKING !!!!

 if (myString != null && !myString.isEmpty()) {
        return true;
    }
    else {
        return false;
    }

Updated

For Kotlin we check if the string is null or not by following

return myString.isNullOrEmpty() // Returns `true` if this nullable String is either `null` or empty, false otherwise

return myString.isEmpty() // Returns `true` if this char sequence is empty (contains no characters), false otherwise

You need to check that the myString object is null:

if (myString != null) {
    doSomething
}