dogtagexample.java

public class dogtagexample{
    
    /**
     * Checks that a dog tag is valid
     * @param dogTag the dog tag to be checked
     * @return true if the dog tag is a valid dog tag
     */
    public static boolean checkDogTag (String dogTag) {
        if(dogTag.length()!=4)
            throw new IndexOutOfBoundsException();
        int sumOfElements = 0;
        for(int i = 0; i <= 2 ; i++)
            sumOfElements+=Integer.parseInt(dogTag.substring(i,i+1),10);
        char dogID = (char) (70+sumOfElements%10);
        if(dogTag.equals(dogTag.substring(0,3)+dogID))
            return(true);
        else
            return(false);
    }
}