POPCORN HACKS

Popcorn Hack 1.1

y is 20 because in line 2 x is reassigned to 20 then in line 3 the value of x is copied into y making y = 20

Popcorn Hack 1.2

If you write int count = "hello"; you get a compile-time error because in java the type of the value must match the variable’s declared type.

Popcorn Hack 2.1

If a user types “twenty” when nextInt() expects a number a java.util.InputMismatchException is thrown because nextInt() cannot parse non-numeric text

Popcorn Hack 2.2

If a user enters “San Diego” when next() is called next() stores only “San” because it reads until whitespace and “Diego” remains in the buffer.

Popcorn Hack 3

OUTPUT AT THE BOTTOM OF CODE CELL

import java.util.Scanner;

public class InputLesson {
    public static void main(String[] args) {
        System.out.println("=== User Information Program ===\n");
        Scanner sc = new Scanner(System.in);

        // String input
        System.out.print("Enter your full name: ");
        String name = sc.nextLine();
        
        // Integer input
        System.out.print("Enter your age: ");
        int age = sc.nextInt();
        
        // Double input
        System.out.print("Enter your GPA: ");
        double gpa = sc.nextDouble();
        
        // Display results
        System.out.println("\n--- Summary ---");
        System.out.println("Name: " + name);
        System.out.println("Age: " + age + " (next year: " + (age + 1) + ")");
        System.out.println("GPA: " + gpa);
        
        sc.close();
    }
}
InputLesson.main(null);

=== User Information Program ===

Enter your full name: Enter your age: Enter your GPA: 
--- Summary ---
Name: Alice Wonderland
Age: 20 (next year: 21)
GPA: 3.85

HOMEWORK HACKS

HACK 1

import java.util.Scanner;

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

        // Prompt for three integers
        System.out.print("Enter first number: ");
        int num1 = sc.nextInt();

        System.out.print("Enter second number: ");
        int num2 = sc.nextInt();

        System.out.print("Enter third number: ");
        int num3 = sc.nextInt();

        // Calculate average (use double to avoid integer division)
        double average = (num1 + num2 + num3) / 3.0;

        // Display result with two decimal places
        System.out.printf("Average: %.2f%n", average);

        sc.close();
    }
}
InputLesson.main(null);

Enter first number: Enter second number: Enter third number: Average: 30.00

Assignment Statments and Input

Student Teaching Lesson