Using Scanner in Java to await user hitting return key

In summary, the conversation discusses how to use the Scanner class in Java to pause a program and wait for user input. However, the program will not continue unless there is actual input. It is suggested to use a KeyListener from the java.awt.event library to listen for the enter key and perform a wait function. The Scanner class does not have this functionality.
  • #1
mr.hood
8
0
Hi all,

I've been trying to figure out how I can use the Scanner class in Java to pause my program and wait for the user to hit the return key. What I have now looks like this:

Scanner kbd = new Scanner(System.in);
kbd.next();
...

The thing is, the rest of my program won't run unless there is actually some kind of input (i.e. just hitting the return key without any input just makes the program keep waiting for input). Is there a way I can get around this?
 
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  • #2
I don't think that scanner has that functionality. What scanner.next() does is it was for user input and returns the input. It does not accept null characters.

What your looking for is some type of listener. Take a look at the KeyListener class from java.awt.event.* libary. Just perform some wait function and listen for the enter key.
 
  • #3


Hello,

It sounds like you are on the right track with using the Scanner class to wait for user input. However, as you have noticed, the kbd.next() method will only return when there is input from the user. To get around this, you could use the kbd.nextLine() method instead. This will wait for the user to hit the return key before returning, regardless of whether there is input or not. You could also add a prompt for the user to enter some input before hitting return to continue with your program.

Another option would be to use a loop to continuously check for input using the hasNext() method. This way, your program will keep running until the user inputs something and hits return.

I hope this helps. Keep exploring and experimenting with the Scanner class to find the best solution for your program. Good luck!
 

1) How do I use the Scanner class in Java to await the user hitting the return key?

In order to use the Scanner class to await user input, you will need to first create a new Scanner object using the System.in as the parameter. Then, you can use the nextLine() method to await the user hitting the return key and store the input in a variable.

2) Can I use the Scanner class to read input from a file instead of the console?

Yes, you can use the Scanner class to read input from a file by passing in a File object as the parameter when creating the Scanner object. You can then use methods such as hasNext() and nextLine() to read the input from the file.

3) How do I handle errors when using Scanner to await user input?

You can use try-catch blocks to handle any potential errors when using the Scanner class. For example, you can use a try block to await user input and a catch block to handle any InputMismatchException or other errors that may occur.

4) Is it possible to use Scanner to read different types of input, such as integers or booleans?

Yes, the Scanner class has methods such as nextInt() and nextBoolean() that allow you to read input of different data types. You can also use the hasNextInt() and hasNextBoolean() methods to check if the input is of the desired type before reading it.

5) How does the Scanner class handle whitespace and new lines when awaiting user input?

The Scanner class ignores leading whitespace and new lines when awaiting user input. However, if you use the nextLine() method, it will read the entire line, including any whitespace or new lines.

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