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

0 votes
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 */
    }
    /* ... */
}
Apr 27, 2018 in Java by developer_1
• 3,280 points
88 views

3 answers to this question.

0 votes
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.
answered Apr 27, 2018 by Rishabh
• 3,540 points
0 votes

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)) {
    ...
} 
answered Jul 23, 2018 by Daisy
• 8,050 points
0 votes
str != null && str.length() != 0

alternatively

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

or

str != null && !"".equals(str)
answered Sep 11, 2018 by Sushmita
• 6,870 points

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