A half-life is the amount of time it takes for a substance or entity to fall to half its original value. Caffeine has a half-life of about 6 hours in humans. Given caffeine amount (in mg) as input, output the caffeine level after 6, 12, and 24 hours. Output each floating-point value with two digits after the decimal point, which can be achieved as follows: System.out.printf("After 6 hours: %.2f mg\n", yourValue);
A half-life is the amount of time it takes for a substance or entity to fall to half its original value. Caffeine has a half-life of about 6 hours in humans. Given caffeine amount (in mg) as input, output the caffeine level after 6, 12, and 24 hours. Output each floating-point value with two digits after the decimal point, which can be achieved as follows: System.out.printf("After 6 hours: %.2f mg\n", yourValue);
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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Question
Java output caffeine levels
![### Understanding Caffeine Half-Life: Educational Exercise
**Concept Explanation:**
A half-life is the amount of time it takes for a substance or entity to fall to half its original value. In the context of this exercise, we are examining the half-life of caffeine in humans. Caffeine has a half-life of about 6 hours in humans.
**Exercise Objective:**
Given an initial caffeine amount (measured in milligrams), the goal is to calculate and output the caffeine level at specific intervals: after 6, 12, and 24 hours.
**Example Calculation:**
If the initial input of caffeine is 100 mg, the calculation steps are as follows:
- **After 6 hours:** The caffeine level is halved.
```java
100 / 2 = 50.00 mg
```
- **After 12 hours:** The caffeine level is halved again.
```java
50 / 2 = 25.00 mg
```
- **After 24 hours:** The caffeine level is halved once more.
```java
25 / 2 = 6.25 mg
```
**Formatted Output:**
Each floating-point value should be output with two decimal places. This can be achieved using the following command in Java:
```java
System.out.printf("After 6 hours: %.2f mg\n", yourValue);
```
**Input and Output Example:**
If the input is:
```
100
```
The output will be:
```
After 6 hours: 50.00 mg
After 12 hours: 25.00 mg
After 24 hours: 6.25 mg
```
**Additional Information:**
- A cup of coffee contains approximately 100 mg of caffeine.
- A soda typically contains around 40 mg of caffeine.
- An energy drink (though a misnomer) can have between 100 mg and 200 mg of caffeine.
**Lab Activity:**
This is part of lab activity 2.19.1 - LAB: Caffeine levels.
**Java Sample Code:**
Here's a simple Java program that performs the described calculations:
```java
import java.util.Scanner;
public class LabProgram {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
double caffeineAmount;
caffeineAmount = scnr.nextDouble();](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fc8f23c41-b0a2-4b7f-b455-de9ffcd4a71a%2F08fca281-0704-46ce-8f1c-370cdb81bcf9%2F0ql1k6m_processed.jpeg&w=3840&q=75)
Transcribed Image Text:### Understanding Caffeine Half-Life: Educational Exercise
**Concept Explanation:**
A half-life is the amount of time it takes for a substance or entity to fall to half its original value. In the context of this exercise, we are examining the half-life of caffeine in humans. Caffeine has a half-life of about 6 hours in humans.
**Exercise Objective:**
Given an initial caffeine amount (measured in milligrams), the goal is to calculate and output the caffeine level at specific intervals: after 6, 12, and 24 hours.
**Example Calculation:**
If the initial input of caffeine is 100 mg, the calculation steps are as follows:
- **After 6 hours:** The caffeine level is halved.
```java
100 / 2 = 50.00 mg
```
- **After 12 hours:** The caffeine level is halved again.
```java
50 / 2 = 25.00 mg
```
- **After 24 hours:** The caffeine level is halved once more.
```java
25 / 2 = 6.25 mg
```
**Formatted Output:**
Each floating-point value should be output with two decimal places. This can be achieved using the following command in Java:
```java
System.out.printf("After 6 hours: %.2f mg\n", yourValue);
```
**Input and Output Example:**
If the input is:
```
100
```
The output will be:
```
After 6 hours: 50.00 mg
After 12 hours: 25.00 mg
After 24 hours: 6.25 mg
```
**Additional Information:**
- A cup of coffee contains approximately 100 mg of caffeine.
- A soda typically contains around 40 mg of caffeine.
- An energy drink (though a misnomer) can have between 100 mg and 200 mg of caffeine.
**Lab Activity:**
This is part of lab activity 2.19.1 - LAB: Caffeine levels.
**Java Sample Code:**
Here's a simple Java program that performs the described calculations:
```java
import java.util.Scanner;
public class LabProgram {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
double caffeineAmount;
caffeineAmount = scnr.nextDouble();
![### Introduction to Basic Java Input Handling
Below is an example of a simple Java program designed to accept user input and handle it appropriately using the `Scanner` class. Follow the instructions and comments in the code to understand how it works.
#### Code Example: LabProgram.java
```java
import java.util.Scanner;
public class LabProgram {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
// Declare a variable to store the caffeine measurement
double caffeineMg; // "double" supports floating-point numbers like 75.5, versus int for integers like 75.
// Read a double from the user
caffeineMg = scnr.nextDouble();
/* Type your code here. */
}
}
```
#### Understanding the Code:
1. **Importing the Scanner class**:
```java
import java.util.Scanner;
```
- This line imports the `Scanner` class, which is used to get user input.
2. **Main Class Definition**:
```java
public class LabProgram {
```
- This defines a public class named `LabProgram`.
3. **Main Method**:
```java
public static void main(String[] args) {
```
- The `main` method is the entry point of the program.
4. **Creating a Scanner object**:
```java
Scanner scnr = new Scanner(System.in);
```
- This line creates a new `Scanner` object named `scnr` to read input from the standard input stream (keyboard).
5. **Variable Declaration**:
```java
double caffeineMg; // "double" supports floating-point numbers like 75.5, versus int for integers like 75.
```
- Declares a double variable `caffeineMg` to store the caffeine amount in milligrams.
6. **Reading User Input**:
```java
caffeineMg = scnr.nextDouble();
```
- Reads a floating-point number from the user and assigns it to the variable `caffeineMg`.
7. **Placeholder for Additional Code**:
```java
/* Type your code here. */
```
- This comment indicates where additional code can be added to process or use the input gathered.
#### Additional Features:
This interface shows a development environment where students can write, test, and submit their code:
- **](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fc8f23c41-b0a2-4b7f-b455-de9ffcd4a71a%2F08fca281-0704-46ce-8f1c-370cdb81bcf9%2Fenpu5nn_processed.jpeg&w=3840&q=75)
Transcribed Image Text:### Introduction to Basic Java Input Handling
Below is an example of a simple Java program designed to accept user input and handle it appropriately using the `Scanner` class. Follow the instructions and comments in the code to understand how it works.
#### Code Example: LabProgram.java
```java
import java.util.Scanner;
public class LabProgram {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
// Declare a variable to store the caffeine measurement
double caffeineMg; // "double" supports floating-point numbers like 75.5, versus int for integers like 75.
// Read a double from the user
caffeineMg = scnr.nextDouble();
/* Type your code here. */
}
}
```
#### Understanding the Code:
1. **Importing the Scanner class**:
```java
import java.util.Scanner;
```
- This line imports the `Scanner` class, which is used to get user input.
2. **Main Class Definition**:
```java
public class LabProgram {
```
- This defines a public class named `LabProgram`.
3. **Main Method**:
```java
public static void main(String[] args) {
```
- The `main` method is the entry point of the program.
4. **Creating a Scanner object**:
```java
Scanner scnr = new Scanner(System.in);
```
- This line creates a new `Scanner` object named `scnr` to read input from the standard input stream (keyboard).
5. **Variable Declaration**:
```java
double caffeineMg; // "double" supports floating-point numbers like 75.5, versus int for integers like 75.
```
- Declares a double variable `caffeineMg` to store the caffeine amount in milligrams.
6. **Reading User Input**:
```java
caffeineMg = scnr.nextDouble();
```
- Reads a floating-point number from the user and assigns it to the variable `caffeineMg`.
7. **Placeholder for Additional Code**:
```java
/* Type your code here. */
```
- This comment indicates where additional code can be added to process or use the input gathered.
#### Additional Features:
This interface shows a development environment where students can write, test, and submit their code:
- **
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