Java program to check if a string contains only numbers

To verify if a string only contains numbers, you can try the following code. Wematches()Here we use the method in Java to check for numbers in a string.

Example

public class Demo {
　　　public static void main(String []args) {
　　　　　　String str = "978";
　　　　　　System.out.println("Checking for a string that only contains numbers...");
　　　　　　System.out.println("String: ");+str);
　　　　　　if(str.matches("[0-9]+)&& str.length() >　2)
　　　　　　System.out.println("Strings only contain numbers!");
　　　　　　else
　　　　　　System.out.println("Strings also contain characters!");
　　　}
}

Output Result

Checking for a string that only contains numbers...
String:　978
Strings only contain numbers!

Let's look at another example where our string contains both numbers and characters.

Example

public class Demo {
　　　public static void main(String []args) {
　　　　　　String str = "s987jyg";
　　　　　　System.out.println("Checking for a string that only contains numbers...");
　　　　　　System.out.println("String: ");+str);
　　　　　　if(str.matches("[0-9]+)&& str.length() >　2)
　　　　　　System.out.println("Strings only contain numbers!");
　　　　　　else
　　　　　　System.out.println("Strings also contain characters!");
　　　}
}

Output Result

Checking for a string that only contains numbers...
String: s987jyg
Strings also contain characters!