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 the 'str' is empty or not**")
{
/* handle empty string */
}
/* ... */
}
What about isEmpty() ?
if(str != null && !str.isEmpty())
Be sure to use the parts of &&
in this order, because java will not proceed to evaluate the second part if the first part of &&
fails, thus ensuring you will not get a null pointer exception from str.isEmpty()
if str
is null.
Beware, it's only available since Java SE 1.6. You have to check str.length() == 0
on previous versions.
To ignore whitespace as well:
if(str != null && !str.trim().isEmpty())
(since Java 11 str.trim().isEmpty()
can be reduced to str.isBlank()
which will also test for other Unicode white spaces)
Wrapped in a handy function:
public static boolean empty( final String s ) {
// Null-safe, short-circuit evaluation.
return s == null || s.trim().isEmpty();
}
Becomes:
if( !empty( str ) )