Dificuldade com Double

public class DecimalDouble {

double num = 0.0;

public void setNum(double num){
this.num = num;
}

public double getNum(){
return num;
}

public static void main(String args[]){
DecimalDouble dd = new DecimalDouble();
dd.setNum(0.6900);
System.out.println("Número: "+dd.getNum());
}
}