Error "variable is never read"

[Phitur]

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

[Phitur]

Sorry for the horrible way the code shows up. Actually the error says, "xm cannot be resolved to a variable". when I tell it to make one, it says the previous instances are not read. Same for ym.

Thanks.

[al_Marshy_1981]

you have declared xm and ym more than once

[Norm]

Remember the scope rules for defining variables. Those defined inside {} are NOT known outside the {}

[JosAH]

you have declared xm and ym more than once

... in several separate blocks (scopes); inside those blocks those variables are never read.

kind regards,

Jos

[Phitur]

Thanks for all the help. I didn't realize it didn't carry through. I think it would have been simpler if it did. Wrote it a different way that got it to work. Is there a way that one could allow the variables to cross those boundaries?

[Zack]

int a = 5;
if (true) {
    int b = 6;
    a = 6;
    // a == 6, b == 6
}
// a == 6, b is an error

The first line in the above code is representative of how you would accomplish this task. If it wasn't an integer, you could use null or another initializer value to assign to the value.

The reason it does not follow the "simpler" method that you describe is that, in case that if block does not execute, then there would be no variable and the VM would not know what to do.