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Can we use Scanner(System.in).nextInt() in java?

Can this statement be used in Java:

int a = new Scanner(System.in).nextInt();


If it can, can anyone explain it to me?

new

Scanner

6 Answers
6

You can do it this way also, but you are not assigning the Scanner object to any reference variable. So if you want to read any input again you would need to create another Scanner object.

Scanner

Scanner

int a = new Scanner(System.in).nextInt();


The best approach is to create a Scanner object and store it in a reference variable.

Scanner

Scanner sc = new Scanner(System.in);


Scanner is a class and nextInt() isn't static method
so,you must use new keyword to make Scanner object, and then you can use that method

Scanner

nextInt()

new

Scanner

Yes, the following code would work:

System.out.println("Enter a number: ");
int k = new Scanner(System.in).nextInt();
System.out.println(k);


Why? You are declaring an int (k). You are setting it's value equal to a new instance of the Scanner object that we are creating which will store the int primitive that we choose to enter. So the type is compatible. IF you attempted to use the Scanner.next() method used for strings, or the Scanner.nextFloat() method, they would not be compatable. Since we will be storing an integer however, there is no compilation error with this statement.

BUT just because you can do something in Java doesn't mean that you should. It is a better practice to first create a Scanner object, and then create the int variable:

System.out.println("Enter a number: ");
Scanner reader = new Scanner(System.in);
int k = reader.nextInt();


This statement is not right. You have to create an object of class Scanner by using the new operator as shown below.

Scanner

new

Scanner sc = new Scanner(System.in);
int val = sc.nextInt();


new

new

new Scanner(System.in)

Your statement is not correct. It needs to be the following:

int value = new Scanner(System.in).nextInt();


Only do this if you are not planning to use the Scanner object again.

Scanner

Yes it can be used.

Assigning it to a Scanner object and calling a function is popular choice and also it increases readability.

It is important to assign it to a Scanner object when you want to use it more than once.

Example:

Scanner sc = new Scanner(System.in);

int sum = 0, count = 0;

while (sc.hasNextInt())

int num = sc.nextInt();
sum += num;
count++;



here you are using the same object more than once.

But if you are going to do something like this,

Scanner sc = new Scanner(System.in);

int num = sc.nextInt();

System.out.println("num " + num);


here you are using the object only once.

It is not really important to assign it to object and call the function. You can simply do this

System.out.println("num" + new Scanner(System.in).nextInt());


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