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Java / Using String

How to check if a string is not null and not empty in Java?

String.isEmpty() non-static method is introduced in Java SE 1.6 that evaluates the string object is empty or not given that the string object is not null otherwise it throws NullPointerException.

if(str != null && !str.isEmpty())

Be sure to use the left and the right conditions of && operator in the above order, as Java will not evaluate the right operand if the left operand is false, thus preventing the NullPointerException being thrown from str.isEmpty() if str is null.

To ignore the white space, use the trim method as shown below.

if(str != null && !str.trim().isEmpty())

Prior to Java SE 1.6, string.length method could be used to evaluate if the string is empty or not.

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

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System.out.println ("A"=="A");

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Java / Using String

How to check if a string is not null and not empty in Java?

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