How to check if a string contains only numbers in Java

Sometimes we deal with strings, and we need to determine whether a string is a valid number or not. In this tutorial, we are going to see how to check that a string contains only numbers in Java.

To check if the string contains only numbers, in the try{} block we use the parseFloat() method of the Float class to convert the string to a Float.

If it returns an error, that means the string is not a number.
 

 

How to check if a string contains only numbers in Jav:

public class Main {

    public static void main(String[] args) {

        String str = "985.12";
        boolean b = true;

        try {
            Float f = Float.parseFloat(str);
        } catch (NumberFormatException e) {
            b = false;
        }

        if(b == true)
            System.out.println(str+" is a number");
        else
            System.out.println(str+" is not a number");
    }
}

Output:

985.12 is a number

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