How to create a object to call method for interface?

Can you help me to modify this code? I want my code to display the addition method and subtraction in two classes also.

interface TypeOfNumber
{
int a=10;
int b=6;

void addition(int a,int b);

void subtraction(int a,int b);
}

class Integers implements TypeOfNumber {

public void addition()

{
System.out.println(“The sum is :”+(a+b));
}

public void subtraction()
{
System.out.println(“The difference is :”+(a+b));
}

class Floats implements TypeOfNumber {

public void addition()
{
System.out.println("The sum of the two float nums are: "+(a+b));
}

public void subtraction()
{
System.out.println("The difference of the two float nums are: "+(a+b));
}

class TestTheNumber {

public static void main(String args[]) {

TypeOfNumber obj=new Integers(10,6);

obj.addition(TypeOfNumber.addition)

//