Use Scanner in Rechargeable Menu Mode
I can't get my menu "reload" way to work, and it looks like it has something to do with the scanner.
I'm sure this is a simple solution, but I just can't seem to find it
public class menuControl
{
public static void main(String[] args)
{
switch (menu())
{
case 1: System.out.println(1); menu();break;
case 2: System.out.println(2); menu();break;
case 3: System.out.println(3); menu();break;
case 4: System.out.println(4); menu();break;
case 0: System.out.println(0); menu();break;
}
}
public static int menu()
{
Scanner in = new Scanner(System.in);
System.out.println("Choice 1");
System.out.println("Choice 2");
System.out.println("Choice 3");
System.out.println("Choice 4");
System.out.print("Choose: ");
int choice = in.nextInt();
System.out.println();
in.close();
if (choice > 0 && choice < 5)
{
return choice;
}
else
{
System.out.println("Wrong choice!");
return 0;
}
}
}
I am getting this error message:
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at Cashmachine.menu(Cashmachine.java:47) //The line"int choice = in.nextInt();"
at Cashmachine.main(Cashmachine.java:23) //The line "case 1: System.out.println(1); menu();break;"
+3
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1 answer
Delete in.close()
. Yours Scanner
transfers global System.in
as soon as you close()
can't use nextInt()
.
You can extract Scanner
in field (or argument) like
public static int menu(Scanner in) {
// Scanner in = new Scanner(System.in);
// ...
// in.close();
// ...
And I think you need a loop in main()
for example
Scanner in = new Scanner(System.in);
for (;;) {
switch (menu(in)) {
case 1:
System.out.println(1);
break;
case 2:
System.out.println(2);
break;
case 3:
System.out.println(3);
break;
case 4:
System.out.println(4);
break;
case 0:
System.out.println(0);
break;
}
}
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