Check whether a string is not null and not empty

Question

How can I check whether a string is not null and not empty?

public void doStuff(String str)
{
    if (str != null && str != \"**here I want to check          


        

Answer 1

In case you are using Java 8 and want to have a more Functional Programming approach, you can define a Function that manages the control and then you can reuse it and apply() whenever is needed.

Coming to practice, you can define the Function as

Function isNotEmpty = s -> s != null && !"".equals(s)

Then, you can use it by simply calling the apply() method as:

String emptyString = "";
isNotEmpty.apply(emptyString); // this will return false

String notEmptyString = "StackOverflow";
isNotEmpty.apply(notEmptyString); // this will return true

If you prefer, you can define a Function that checks if the String is empty and then negate it with !.

In this case, the Function will look like as :

Function isEmpty = s -> s == null || "".equals(s)

Then, you can use it by simply calling the apply() method as:

String emptyString = "";
!isEmpty.apply(emptyString); // this will return false

String notEmptyString = "StackOverflow";
!isEmpty.apply(notEmptyString); // this will return true