Java String isEmpty() Method Examples

Java String isEmpty() method returns true if the string length is 0, else returns false. This utility method was added to String class in Java 1.6 version.

Java String isEmpty() Method Implementation

The internal implementation of isEmpty() method is:

public boolean isEmpty() {
    return value.length == 0;
}

Java String isEmpty() Method Examples

Let’s look at some examples of using isEmpty() method.

1. String is empty

jshell> String s = "";
s ==> ""

jshell> s.isEmpty();
$54 ==> true

2. The string is not empty

jshell> String message = "Hello";
message ==> "Hello"

jshell> message.isEmpty();
$56 ==> false

3. String is null

If the string is null, calling isEmpty() method will throw NullPointerException.

jshell> String str = null;
str ==> null

jshell> str.isEmpty();
|  Exception java.lang.NullPointerException
|        at (#58:1)

Conclusion

Java String isEmpty() method comes handy when we have to check if the string is empty or not. It’s a very trivial operation and earlier we had to use length() method or write our own isEmpty() method implementation. That’s why this method has been added in the String class.

References:

• String isEmpty() API Doc