The document provides a Java class definition for a 'Bag' that includes private instance variables for managing the bag's name, current weight, and maximum weight, along with methods for modifying these attributes. It also includes a 'BagDemo' class with a main method that interacts with the user, allowing them to change the bag's name, add items, change maximum weight, and view bag information through a console interface. The implementation details, including constructors and method functionalities, are thoroughly outlined.

1. Please write the class and class with main method clearly!! This is to be written in JAVA.
Step 1 Develop the following class:
Class
Name: Bag
Access Modifier: public
Instance variables
1-Name: name
Access modifier: private
Data Type: String
2-Name: currentWeight
Access modifier: private
Data Type: double
3-Name: maximumWeight
Access modifier: private
Data Type: double
Constructors
Name: Bag
Access modifier: public
Parameters: none (default constructor)
Task: sets the value of the instance variable name to the empty string sets the value of the
instance variable currentWeight to 0.0 sets the value of the instance variable maximumWeight to
5.0
Methods
Name: setName
Access modifier: public
Parameters: newName
Return Type: void
Task: sets the value of the instance variable name to newName
Name: getName
Access modifier: public
Parameters: none
Return Type: String
Task: returns the value of the instance variable name
Name: addItem
Access modifier: public

2. Parameters: newWeight Return
Type: void
Task: sets the value of the instance variable currentWeight equal to the value of currentWeight
plus the value of newWeight if the value of newWeight is greater than 0 and if the value of
currentWeight plus the value of newWeight is less than or equal to the value of the instance
variable maximumWeight
Name: getCurrentWeight
Access modifier: public
Parameters: none
Return Type: double
Task: returns the value of the instance variable currentWeight
Name: setMaximumWeight
Access modifier: public
Parameters: newMaximumWeight
Return Type: void
Task: sets the value of the instance variable maximumWeight to value of the
newMaximumWeight if newMaximumWeight is greater than 0 and greater than or equal to the
value of the instance variable currentWeight
Name: getMaximumWeight
Access modifier: public
Parameters: none
Return Type: double
Task: returns the value of the instance variable maximumWeight
Step 2
Develop a class with only a main method in it:
import java.util.Scanner;
public class BagDemo {
public static void main(String[] args) {
//Create a Scanner object called keyboard that takes input from //System.in //Create an object of
the Bag class refer to this object as myBag //declare a variable called option of type int //Open a
do/while loop //Prompt the user to pick one of the following options: //Press 1 to change the
name of the bag //Press 2 to add an item to the bag //Press 3 to change the maximum weight of
the bag //Press 4 to view all information about the bag //Press 5 to end the program //Save the
user’s input into the option variable //if the user picks option 1, prompt the user for the name of
the bag //then save the name of the bag in a variable called newName //change the name of the
bag to newName //else if the user picks option 2, prompt the user for the weight //of the item and

3. then save the weight of the item in a variable //called newWeight //add the new item to the bag
//else if the user picks option 3, prompt the user for the new maximum //weight of the bag and
save the new maximum weight in a variable //called newMaximumWeight //change the
maximum weight of the bag to newMaximumWeight //else if the user picks option 4, display to
the screen the name of //the bag, the current weight of the bag, and the maximum weight //of the
bag //else if the user picks option 5, display Goodbye. //else if the user picks any other option,
display Error! //close the do/while loop and make it so that it continues to run as //long as the
user does not pick option 5 } }
Solution
HI, Please find my implementation.
Please let me know in case of any issue.
############### Bag.java ########################
public class Bag {
// instance variables
private String name;
private double currentWeight;
private double maximumWeight;
// constructor
public Bag() {
name = "";
currentWeight = 0.0;
maximumWeight = 5.0;
}
public void setName(String newName){
name = newName;
}
public String getName(){
return name;
}

4. public void addItem(double newWeight){
double total = currentWeight + newWeight;
if(newWeight > 0 && total <= maximumWeight)
currentWeight = total;
}
public double getCurrentWeight(){
return currentWeight;
}
public void setMaximumWeight(double newMaximumWeight){
if(newMaximumWeight >0 && (currentWeight <= newMaximumWeight))
maximumWeight = newMaximumWeight;
}
public double getMaximumWeight(){
return maximumWeight;
}
}
############### BagDemo.java ###############
import java.util.Scanner;
public class BagDemo {
public static void main(String[] args) {
//Create a Scanner object called keyboard that takes input from //System.in
Scanner sc = new Scanner(System.in);
//Create an object of the Bag class refer to this object as myBag
Bag myBag = new Bag();
//declare a variable called option of type int
int option;
//Open a do/while loop //Prompt the user to pick one of the following options:
//Press 1 to change the name of the bag
//Press 2 to add an item to the bag
//Press 3 to change the maximum weight of the bag
//Press 4 to view all information about the bag
//Press 5 to end the program

5. do{
System.out.println("Press 1 to change the name of the bag");
System.out.println("Press 2 to add an item to the bag ");
System.out.println("Press 3 to change the maximum weight of the bag ");
System.out.println("Press 4 to view all information about the bag");
System.out.println("Press 5 to end the program ");
//Save the user’s input into the option variable
option = sc.nextInt();
//if the user picks option 1, prompt the user for the name of the bag
//then save the name of the bag in a variable called newName
//change the name of the bag to newName
if(option == 1){
System.out.print("Enter name: ");
String newName = sc.next();
myBag.setName(newName);
}
//else if the user picks option 2, prompt the user for the weight
//of the item and then save the weight of the item in a variable
//called newWeight //add the new item to the bag
else if(option == 2){
System.out.print("Enter weight of the item: ");
double newWeight = sc.nextDouble();
myBag.addItem(newWeight);
}
//else if the user picks option 3, prompt the user for the new maximum
//weight of the bag and save the new maximum weight in a variable
//called newMaximumWeight //change the maximum weight of the bag to
newMaximumWeight
else if(option == 3){
System.out.print("Enter new max weight: ");
double newMaximumWeight = sc.nextDouble();
myBag.setMaximumWeight(newMaximumWeight);
}
//else if the user picks option 4, display to the screen the name of
//the bag, the current weight of the bag, and the maximum weight
//of the bag

6. else if(option == 4){
System.out.println("Name: "+myBag.getName());
System.out.println("Current Weight: "+myBag.getCurrentWeight());
System.out.println("Max Weight: "+myBag.getMaximumWeight());
}
//else if the user picks option 5, display Goodbye.
else if(option == 5){
System.out.println("Goodbye");
}
//else if the user picks any other option, display Error!
//close the do/while loop and make it so that it continues to run as
//long as the user does not pick option 5
else{
System.out.println("Invalid option!!!");
}
}while(option != 5);
}
}
/*
Sample run:
Press 1 to change the name of the bag
Press 2 to add an item to the bag
Press 3 to change the maximum weight of the bag
Press 4 to view all information about the bag
Press 5 to end the program
1
Enter name: AmericalTourist
Press 1 to change the name of the bag
Press 2 to add an item to the bag
Press 3 to change the maximum weight of the bag
Press 4 to view all information about the bag
Press 5 to end the program
2
Enter weight of the item: 34
Press 1 to change the name of the bag
Press 2 to add an item to the bag

7. Press 3 to change the maximum weight of the bag
Press 4 to view all information about the bag
Press 5 to end the program
3
Enter new max weight: 50
Press 1 to change the name of the bag
Press 2 to add an item to the bag
Press 3 to change the maximum weight of the bag
Press 4 to view all information about the bag
Press 5 to end the program
2
Enter weight of the item: 34
Press 1 to change the name of the bag
Press 2 to add an item to the bag
Press 3 to change the maximum weight of the bag
Press 4 to view all information about the bag
Press 5 to end the program
4
Name: AmericalTourist
Current Weight: 34.0
Max Weight: 50.0
Press 1 to change the name of the bag
Press 2 to add an item to the bag
Press 3 to change the maximum weight of the bag
Press 4 to view all information about the bag
Press 5 to end the program
5
Goodbye
*/