Error "variable is never read"

I'm trying to perform a simple calculation based on some parameters. The problem is, I think I've defined xm and ym, btu the code doesn't like it. How do I get this to go forward to the calculation portion on the bottom?

Code:

public static void drawLines(){

Display myDisplay = new Display();

for (int cnt = 0; cnt < 4; cnt++){

for(int count = 0; count < 200; count++){

if (cnt == 0){

int xm = 1;

int ym = 0;

} else if (cnt == 1){

int xm = 0;

int ym = -1;

} else if (cnt == 2){

int xm = -1;

int ym = 0;

} else {

int xm = 0;

int ym = 1;

}

int x = count * xm + 100;

int y = count * ym + 100;

myDisplay.drawNextPixel(x,y);

}

}

}

Thanks