Java一起打印两行

Question

I'm trying to print a message on the screen and after that, take a value from the keyboard. i have 4 prints in a row but i have scan methods between them. When i run my code, the first two prints run together and i can't insert a value at the first variable, after the first print.

case 1:
            System.out.println("###Book Data###");
            System.out.print("Name of the book:\t");
            String Name = key.nextLine();

            System.out.print("ISBN of the book:\t");
            String ISBN = key.nextLine();

            System.out.print("Author of the book:\t");
            String author = key.nextLine();

            System.out.print("Copies of the book:\t");
            int copies = key.nextInt();
            book Book = new book(ISBN,Name,author,copies);
            lib.AddBook(Book);
            break;


#########Text Printed######
Please enter your selection:    1
###Book Data###
Name of the book:       ISBN of the book:

Thanks in advance for your help!

Answer 1

println makes a new line while print does not. You should consider either using println, flushing the buffer, or calling a new line escape character "\\n"

Answer 2

This is because the line above your switch statement has key.nextInt() ^* .

The scanner reads the integer, but it leaves the end-of-line character '\\n' in the buffer. You need to consume that '\\n' character somehow, before the key.nextLine(); inside the switch statement returns some relevant data to you.

To fix this problem, insert

key.nextLine();

in front of the switch statement.

^* don't ask me how I know that :-)