Different Java Scanner for input of different types

Question

Imagine the following scanario: I have a program which ask for an integer input, followed by a String input.

int age=0;
String name;
Scanner sc = new Scanner(System.in);

System.out.print("Enter Age: ");
age = sc.nextInt();
System.out.print("Enter Name: ");
name= sc.nextLine();

With the aobe codes, I was not given a chance to enter the name. So normally I will declare 2 scanner objects as follows:

int age=0;
String name;
Scanner sc = new Scanner(System.in);
Scanner sc2 = new Scanner(System.in);    //2nd Scanner object

System.out.print("Enter Age: ");
age = sc.nextInt();
System.out.print("Enter Name: ");
name= sc2.nextLine();                    //Using 2nd Scanner Object

My question is: Is it necessary to declare multiple scanner objects to accept inputs of different types?? Am I doing the proper way as aobve?

I have this question in mind for years already. (Several questions in SO mention multiple scanner, but their questions only used one scanner object, so I am asking this today.)

Answer 1

@skiwi is right about only using one Scanner, so you're doing that right. The reason it doesn't work is that nextInt() consumes all characters that make up the integer, but it does not touch the end-of-line character. So when nextLine() is called, it sees that there are no characters before the end-of-line character, so it thinks that an empty line was entered, and you get an empty String back. However, nextLine() does consume the end-of-line character, so if you call sc.nextLine(); once before you do name = sc.nextLine();, it should work.

Answer 2

You were not given a chance to enter the name because nextInt() doesn't read the new-line character '\n' (inputted by user after pressing Enter), whereas nextLine() does. So as soon as you call name = sc.nextLine();, it will just read the '\n' character that the nextInt() didn't read already.

Definitely do not create a new Scanner if the Scanner if you're scanning the same thing (like System.in) - only change Scanners if you are scanning something else, like different files or something.

To get your code working (with only one Scanner instance), use this:

int age = 0;
String name;
Scanner sc = new Scanner(System.in);

System.out.print("Enter Age: ");
age = sc.nextInt();
System.out.print("Enter Name: ");

sc.nextLine(); // "dispose" of the '\n' character
               // so that it is not recorded by the next line

name = sc.nextLine();

// print your findings
System.out.println("------\nAge: " + age + "\nName: " + name);

Example input/output:

Enter Age: 17
Enter Name: Michael
------
Age: 17
Name: Michael