Comparing String to int JAVA

Question

I am trying to figure out how to make sure a String variable does not have a number as a string. I cannot Import anything.

I have tried

NameArray[i].equalsIgnoreCase("")) || Integer.parseInt(NameArray[i]) >= 48 && Integer.parseInt(NameArray[i]) < 58

but it did not work.

Answer 1

You can try converting string to number using Integer.parseInt(string). If it gives an Exception than it is not a number.

public boolean validNumber(String number) 
{
   try 
   {
     Integer.parseInt(number);
   } 
   catch (NumberFormatException e) 
   {
     return false;
   }
   return true;
}

Answer 2

In Java 8+, you might use an IntStream to generate a range ( [48, 58] ) and then check if that as a String is equal to your NameArray . Something like,

if (IntStream.rangeClosed(48, 58).anyMatch(x -> String.valueOf(x)
        .equals(NameArray[i]))) {

}

You mention that you want to make sure it doesn't contain a value - so perhaps you really want noneMatch like

if (IntStream.rangeClosed(48, 58).noneMatch(x -> String.valueOf(x)
        .equals(NameArray[i]))) {

}

Answer 3

So, you need to check for a string which doesn't contain any numbers. Try using regex .*[0-9].* which will check for occurrence of any numerical character in your string.

    String regex = ".*[0-9].*";

    // Returns true
    System.out.println("1".matches(regex));
    System.out.println("100".matches(regex));
    System.out.println("Stack 12 Overflow".matches(regex));
    System.out.println("aa123bb".matches(regex));

    // Returns false
    System.out.println("Regex".matches(regex));
    System.out.println("Java".matches(regex));