How know if a string contains only numbers in java?

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I need to know if a String in Java, that it enters as a parameter, contains only numbers. I know that exists a method of String class, that let's you detect that.

What I have tried:

I tried to compare each character using Ascii code, conditionals and an ArrayList that contains each character of the String, but this solution is very inefficient.

Posted 14-May-18 4:56am

Jorge Echeverria Raddatz

Updated 14-May-18 6:18am

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2 solutions

Solution 2

Java gently provides the Character.isDigit[^] method. You may call it iteratively.

Posted 14-May-18 6:19am

CPallini

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OriginalGriff · Accepted Answer · 2018-05-14T05:15:00

Solution 1

Use a Regex: Lesson: Regular Expressions (The Java™ Tutorials > Essential Classes)[^]
Then it's trivial:

^\d+$

Is all the pattern you need.

Posted 14-May-18 5:15am

OriginalGriff

Comments

Jorge Echeverria Raddatz 14-May-18 11:47am

Thanks for your help.

OriginalGriff 14-May-18 11:58am

You're welcome!

CPallini 14-May-18 12:18pm

5.