double a;
for (int i = 0; i < 10; i++) {
a = Double.parseDouble(
JOptionPane.showInputDialog("Input a nonnegative real"));
if (a >= 0)
System.out.println(Math.sqrt(a));
else {
System.out.println("Error");
break;
}
}
is equivalent to
double a;
boolean error = false;
for (int i = 0; (i < 10) && !error; i++) {
a = Double.parseDouble(
JOptionPane.showInputDialog("Input a nonnegative real"));
if (a >= 0)
System.out.println(Math.sqrt(a));
else {
System.out.println("Error");
error = true;
}
}