Example: How to Print an Integer entered by an user
import java.util.Scanner;
public class HelloWorld {
public static void main(String[] args) {
// Creates a reader instance which takes
// input from standard input - keyboard
Scanner reader = new Scanner(System.in);
System.out.print("Enter a number: ");
// nextInt() reads the next integer from the keyboard
int number = reader.nextInt();
// println() prints the following line to the output screen
System.out.println("You entered: " + number);
}
}
Output
Enter a number: 10 You entered: 10
In this program, an object of Scanner
class, reader is created to take inputs from standard input, which is keyboard
.
Then, Enter a number
prompt is printed to give the user a visual cue as to what they should do next.
reader.nextInt()
then reads all entered integers from the keyboard unless it encounters a new line character \n (Enter)
. The entered integers are then saved to the integer variable number.
If you enter any character which is not an integer, the compiler will throw an InputMismatchException
.
Finally, number is printed onto the standard output (System.out
) - computer screen using the function println()
.