Java – why use printf (‘% s’) to pass parameters to generic methods?

package genericMethods;

package genericMethods;

public class OverloadedMethods {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Integer[] integerArray = {1,2,3,4,5};
        Double[] doubleArray = {1.0,2.0,3.0,4.0,5.0};
        Character[] charArray = {'a','b','c','d'};

        System.out.println("A has: ");
        printArray(integerArray);
        System.out.println("B has: ");
        printArray(doubleArray);
        System.out.println("C has: ");
        printArray(charArray);
    }

    public static <T> void printArray(T[] array)
    {
        for(T element : array)
            System.out.printf("%s ",element);//why use %s instead of others? 

        System.out.println();
    }

}

My problem is that the method printarray () doesn't know what type of data to print out, and it seems that% d will have an error at runtime - but not just% s of string?

Solution

The problem is that you don't know what type of "element" will be In your example, it can be integer, double, or character In this case, you cannot use% d or% lf because they do not apply to types other than integer (for% d) or double (for% LF)

%S actually applies to all of these because all object types have Tostring(), so they can be converted into strings for printing