import org.apache.commons.lang3.StringUtils; public class StringUtilsExample { public static void main(String[] args) { String str1 = "123"; String str2 = "12.3"; String str3 = "abc"; System.out.println(StringUtils.isNumeric(str1)); // true System.out.println(StringUtils.isNumeric(str2)); // false System.out.println(StringUtils.isNumeric(str3)); // false } }In this example, the isNumeric() method is called on three different strings. The first string contains only digits, so isNumeric() returns true. The second string contains a decimal point, so isNumeric() returns false. The third string contains only letters, so isNumeric() also returns false. The package library for the StringUtils class is org.apache.commons.lang3.