Java Scanner Class: Taking Input from the User

1. Watch First: Scanner Class Video

Watch the video carefully. Then use the written lesson below to revise the concept, copy the examples, and solve the practice tasks.

2. What Is Scanner in Java?

In Java, the Scanner class is used to read input. It can read text, numbers, and other values typed by the user.

Before using Scanner, we import it from the Java utility package:

import java.util.Scanner;

3. The Basic Scanner Program

This is the smallest useful pattern for taking input from the keyboard.

import java.util.Scanner;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter your name: ");
        String name = sc.nextLine();

        System.out.println("Hello, " + name);

        sc.close();
    }
}

Explanation

4. Reading Different Types of Input

Scanner has different methods for different data types.

5. Example: Add Two Numbers

import java.util.Scanner;

class AddTwoNumbers {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter first number: ");
        int a = sc.nextInt();

        System.out.print("Enter second number: ");
        int b = sc.nextInt();

        int sum = a + b;

        System.out.println("Sum = " + sum);

        sc.close();
    }
}

6. Example: Student Marks Program

This example is closer to school-level Java practice.

import java.util.Scanner;

class StudentMarks {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter student name: ");
        String name = sc.nextLine();

        System.out.print("Enter marks in Computer Science: ");
        double cs = sc.nextDouble();

        System.out.print("Enter marks in Mathematics: ");
        double maths = sc.nextDouble();

        System.out.print("Enter marks in English: ");
        double english = sc.nextDouble();

        double total = cs + maths + english;
        double average = total / 3;

        System.out.println("Student: " + name);
        System.out.println("Total Marks: " + total);
        System.out.println("Average Marks: " + average);

        sc.close();
    }
}

7. Important Scanner Mistake: nextInt() and nextLine()

Beginners often face a problem when they use nextInt() before nextLine().

Problem Code

import java.util.Scanner;

class ProblemExample {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

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

        System.out.print("Enter full name: ");
        String name = sc.nextLine();

        System.out.println("Age: " + age);
        System.out.println("Name: " + name);

        sc.close();
    }
}

Correct Code

import java.util.Scanner;

class FixedExample {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

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

        sc.nextLine(); // clears the leftover newline

        System.out.print("Enter full name: ");
        String name = sc.nextLine();

        System.out.println("Age: " + age);
        System.out.println("Name: " + name);

        sc.close();
    }
}

8. Scanner with if-else

Scanner becomes more powerful when combined with conditions.

import java.util.Scanner;

class PassFail {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter marks: ");
        int marks = sc.nextInt();

        if (marks >= 33) {
            System.out.println("Result: Pass");
        } else {
            System.out.println("Result: Fail");
        }

        sc.close();
    }
}

9. Scanner with Loops

We can also use Scanner inside loops to repeatedly take input.

import java.util.Scanner;

class FiveNumbers {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int total = 0;

        for (int i = 1; i <= 5; i++) {
            System.out.print("Enter number " + i + ": ");
            int n = sc.nextInt();
            total = total + n;
        }

        System.out.println("Total = " + total);

        sc.close();
    }
}

10. Practice Tasks

11. Mini Project: Student Report Card

Create a Java program that takes:

• Student name
• Roll number
• Marks in English
• Marks in Mathematics
• Marks in Computer Science

Then print:

• Total marks
• Average marks
• Pass or fail result

import java.util.Scanner;

class ReportCard {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter student name: ");
        String name = sc.nextLine();

        System.out.print("Enter roll number: ");
        int roll = sc.nextInt();

        System.out.print("Enter English marks: ");
        int english = sc.nextInt();

        System.out.print("Enter Mathematics marks: ");
        int maths = sc.nextInt();

        System.out.print("Enter Computer Science marks: ");
        int cs = sc.nextInt();

        int total = english + maths + cs;
        double average = total / 3.0;

        System.out.println("\n--- Report Card ---");
        System.out.println("Name: " + name);
        System.out.println("Roll Number: " + roll);
        System.out.println("Total Marks: " + total);
        System.out.println("Average Marks: " + average);

        if (english >= 33 && maths >= 33 && cs >= 33) {
            System.out.println("Result: Pass");
        } else {
            System.out.println("Result: Fail");
        }

        sc.close();
    }
}

12. Lesson Summary

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