if variable might not have been initialized [duplicate]

This question already has an answer here:

• Why does Java say my variable is not initialized when it is? 6 answers

it's give me error on netbeans

could anyone help me. thanks.

double d;
double v;
double p;
String input;

input = JOptionPane.showInputDialog("Please enter the value : ");
v = Double.parseDouble(input);

if (v > 99){
    if(v < 200){
        d = v * 0.05;
        p = v - d;
    } else if (v < 300){
        d = v * 0.10;
        p = v - d;
    } else if (v < 400){
        d = v * 0.15;
        p = v - d;
    } else if (v < 500){
        d = v * 0.20;
        p = v - d;            
    } else if (v > 499){
        d = v * 0.25;
        p = v - d;            
    }

    JOptionPane.showMessageDialog(null , "you\'r discount is : " + d + "\n you have to pay : " + p );

} else{
    // zero 
    JOptionPane.showMessageDialog(null, "there is no discount. ");
}