How to check whether a string is empty or not Is there a function for this

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 the 'str' is empty or not**")
    {
        /* handle empty string */
    }
    /* ... */
}

Answer 1

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.

Answer 2

We can use StringUtils class from org.apache.commons.lang package.

import org.apache.commons.lang.StringUtils;

if (StringUtils.isNotBlank(str)) {
    ...
} 

if (StringUtils.isBlank(str)) {
    ...
} 

Answer 3

str != null && str.length() != 0

alternatively

str != null && !str.equals("")

or

str != null && !"".equals(str)