Determine if a String is an Integer in Java [duplicate]

Answer 1

Using regular expression is better.

str.matches("-?\\d+");


-?     --> negative sign, could have none or one
\\d+   --> one or more digits

It is not good to use NumberFormatException here if you can use if-statement instead.

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If you don't want leading zero's, you can just use the regular expression as follow:

str.matches("-?(0|[1-9]\\d*)");