How to get out of while loop in java with Scanner method hasNext as condition

Question

I am a beginner at java programming and has run into a strange issue  Below is my code  which asks user for input and prints out what the user inputs one word at a time   The problem is the program never ends  and from my limited understanding  it seem to have stuck inside the while loop  Could anyone help me a little  Thanks in advance   import java util Scanner   public class Test     public static void main String args           System out print  Enter your sentence            Scanner sc   new Scanner  System in          while  sc hasNext      true             String s1   sc next            System out println s1                  System out println  The loop has been ended       This somehow never get printed

User · Answer

Your condition is right  though you should drop the    true   What is happening is that the scanner will keep going until it reaches the end of the input  Try Ctrl D  or pipe the input from a file  java myclass  lt  input txt

User · Answer

When you use scanner  as mentioned by Alnitak  you only get  false  for hasNext   when you have a EOF character  basically    You cannot easily send and EOF character using the keyboard  therefore in situations like this  it s common to have a special character or word which you can send to stop execution  for example   String s1   sc next    if  s1 equals  exit          break      Break will get you out of the loop

User · Answer

The Scanner will continue to read until it finds an  end of file  condition   As you re reading from stdin  that ll either be when you send an EOF character  usually  d on Unix   or at the end of the file if you use  lt  style redirection

User · Answer

I had the same problem and I solved it by reading the full line from the console with one scanner object  and then parsing the resulting string using a second scanner object    Scanner console   new Scanner System in   System out println  Enter input here     String inputLine   console nextLine     Scanner input   new Scanner inputLine   List lt String gt  arg   new ArrayList lt  gt      while  input hasNext          arg add input next   toLowerCase

User · Answer

it doesn t work because you have not programmed a fail-safe into the code  java sees that the scanner can still collect input while there is input to be collected and if possible  while that is true  it keeps doing so  having a scanner test to see if a certain word  like EXIT for example  is fine  but you could also have it loop a certain number of times  like ten or so  but the most efficient approach is to ask the user of your program how many strings they wish to enter  and while the number of strings they enter is less than the number they put in  the program shall execute  an added option could be if they type EXIT  when they see they need less spaces than they put in and don t want to fill the next cells up with nothing but whitespace  and you could have the program ask if they want to enter more input  in case they realize they need to enter more data into the computer  the program would be quite simplistic to make  as well because there are a plethera of ways you could do it  feel free to ask me for these ways  i m running out of room though  XD

User · Answer

Modify the while loop as below   Declare s1 as String s1  one time outside the loop   To end the loop  simply use ctrl z     while  sc hasNext                s1   sc next        System out println s1       System out print  Enter your sentence

User · Answer

If you don t want to use an EOF character for this  you can use StringTokenizer    import java util    public class Test     public static void main          Scanner sc   new Scanner  System in         System out print  Enter your sentence            String s sc nextLine          StringTokenizer st new StringTokenizer s            is the delimiter here        while  st hasMoreTokens               String s1   st nextToken            System out println s1                  System out println  The loop has been ended

User · Answer

You keep on getting new a new string and continue the loop if it s not empty  Simply insert a control in the loop for an exit string   while  s1 equals  exit    amp  amp  sc hasNext             operate     If you want to declare the string inside the loop and not to do the operations in the loop body if the string is  exit    while sc hasNext          String s1   sc next        if s1 equals  exit              break              operate

User · Answer

You can simply use one of the system dependent end-of-file indicators   d for Unix Linux Ubuntu   z for windows  to make the while statement false  This should get you out of the loop nicely

[java] How to get out of while loop in java with Scanner method "hasNext" as condition?

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