How to make the java code restart if user enter false number?

Answer 1

You can try something like that (but it will not work in SL Playground):

* * *
Scanner scan = new Scanner(System.in);

int n = 0;

while (true) {
try {
System.out.print("Enter a number [1..1000]: ");
n = Integer.parseInt(scan.nextLine());

// Break if 'n' is in range 1..1000
if (n > 0 && n < 1001) {
break;
}
} catch (Exception e) {
System.out.println("(!) Wrong input...\n");
}
}

System.out.println("The number is: " + n);

* * *

Answer 2

You could:
* Use a loop that continues if the input is false
or
* re-call the method if the input is false

Answer 3

do you have an example?

As java restarts after your program has finished with an output.