Thread: User Input Loop

I've been messing around with this for a bit and cannot seem to code it so that it will work as intended. I'm trying to prompt the user for input repeatedly, until the user enters a -1, when the loop is supposed to terminate.

My problem lies in that the loop does not stop when -1 is entered. What am I doing wrong here?

import java.util.Scanner;
 
class Test{
 
public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    String in = scan.nextLine();
 
    while(in != "-1"){
      System.out.println("You entered: " + in);
      in = scan.nextLine();
 
    if(in == "-1")
      System.out.println("Stopped");
      break;
   }
  }
 }

BTW,

do in.trim().equals("-1") instead of in == "-1"

also print and see what it is printing?

Please note that you are doing redundant check in your while just for entry check.

probably, you could write:

if (!in.trim().equals("-1")) {
while (1) {
....// rest code
if(in.trim().equals("-1"))
System.out.println("Stopped");
break;
}
}
}

Acumen,
Lucid forums

Agreed, I would suggest the same for all cases like

int i = fun();

if (-1 == i) {
// do something
} else {
// do something else
}

In such case u don't end up doing

-1 = i, but i = -1 would have messed up things for you

Acumen,
Lucid forums

while(1) won't work... Java has abstracted that away

Yes, Java's comparison is different because of the way it creates objects for pretty much everything. Using the == operator only compares the addresses the objects are held at, instead of their actual content.