Have loop repeat after invalid entry - loops

Question

All calculating is fine. I run into a problem when I get an invalid entry and the user enters a new positive integer. It doesn't start the loop over again. Any advice is greatly appreciated!
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int start;
int i;
double squareRoot;
System.out.println("Please enter a positive integer: ");
start = in.nextInt();
if (start > 0){
do {
squareRoot = Math.sqrt(start);
start--;
System.out.printf("%.4f", squareRoot);
System.out.println();
}
while (start >= 0);
}
else {
System.out.println("The number you entered is not a postive integer.");
System.out.println("Please enter an integer greater than zero: ");
start = in.nextInt();
}
}
}

Answer 1

If you need to go over the same steps over and over, you need a loop. So add a while loop with a simple condition and get it going over and over.
Here is a sample code. I had to give an option to quit, so took -1 as the cue.
import java.util.Scanner;
public class HelloWorld {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int start;
int i;
double squareRoot;
System.out.println("Please enter a positive integer: ");
boolean quit = false;
while (!quit) {
System.out.println("Enter the integer");
start = in.nextInt();
if (start > 0){
do {
squareRoot = Math.sqrt(start);
start--;
System.out.printf("%.4f", squareRoot);
System.out.println();
}
while (start >= 0);
}
else if (start == -1) {
quit = true;
}
else {
System.out.println("The number you entered is not a postive integer.");
System.out.println("Please enter an integer greater than zero: ");
}
}
}
}