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Rodrigo De Lascio
Rodrigo De Lascio

Posted on • Originally published at rodrigodelascio.co.uk

Scanner Class in Java: Making Your Program Listen to You

#programming #java #learning #tutorial

One of the coolest moments when learning Java is making your program interact with you. Until now, your code has been shouting into the void with System.out.println() statements, and the void (a.k.a. your console) has been silently nodding.

But what if you could make your program listen? Enter the Scanner class, Java’s way of turning your static program into a two way conversation.

Step 1: Import the Scanner Class

Before you can use Scanner, you have to invite it into your code. Think of this as adding someone to the group chat before you start sending them memes.

import java.util.Scanner;
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Without this line, your program will stare at you blankly when you try to use Scanner.

Step 2: Create a Scanner Object

To make your program listen, you create a Scanner object. This is like giving your code a pair of ears.

Scanner input = new Scanner(System.in);
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  • Scanner = the type of object you are creating
  • input = the name you choose (you can call it keyboard, scanner, or even earholes, but maybe keep it professional)
  • System.in = tells Java you want to take input from your keyboard

Step 3: Ask the User Something

Now your program is ready to listen, but it is polite to ask first. Use System.out.println() to prompt the user.

System.out.println("What is your name?");
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Step 4: Capture the Input

When the user types something and presses Enter, you can store it in a variable. For a full line of text, use nextLine().

String name = input.nextLine();
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Now whatever the user typed is saved in the variable name. You can use it anywhere in your program.

Step 5: Respond Like a Chatty Friend

Finally, use that input to make your program respond.

System.out.println("Hello, " + name + "! Nice to meet you.");
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Full Example 

import java.util.Scanner;

public class Greeting {
    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);

        System.out.println("What is your name?");
        String name = input.nextLine();

        System.out.println("Hello, " + name + "! Nice to meet you.");

        input.close();
    }
}
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Pro Tips

  • Always close your Scanner with input.close() when you are done. It is like hanging up the phone politely.
  • For numbers, use nextInt() or nextDouble() instead of nextLine().
  • If things get weird (like nextLine() skipping inputs), it is probably because Scanner is still holding on to leftover input from before. It can be clingy, so you might need to add an extra nextLine() to clear the buffer.

Final Thoughts

Scanner is one of the first tools that makes your Java programs feel alive. It lets you collect information, personalise output, and generally be less of a monologue.

Next step? Combine it with conditionals and loops, and suddenly you have a program that not only listens but also makes decisions. Just do not let it get too smart, because that is how sci-fi movies start.

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