1) productType that have name and price of the productType and an empty consturcor. 2) superMarket that have name of supermarket and arraylist of productTypes (
private ArrayList<ProductType> products;
) and an empty constructor.
In each class I have function that get input from console and should store it into each class variables.
In productType i have function:
public void getFromUser() throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("Enter product name:"); name = br.readLine(); System.out.println("Enter price:"); price = Integer.parseInt(br.readLine());
[Code] ....
The main is something like:
public static void main(String[] args) throws IOException{ SuperMarket s1 = new SuperMarket(); SuperMarket s2 = new SuperMarket(); s1.getFromUser(); }
The problem is when i get to line "products.add(i,p)" I get java.lang.NullPointerException
In the debug mode I can see that when I get to this line the "products" is null.
why do you think this happening, when I do "new SuperMarker()" in the main it should run the empty constructor and create new arraylist...
The LocalStudent class inherits the Student class. The IDE states an error of "no default constructor in Student class".I understand that if a LocalStudent object is created, the default constructor of its superclass (aka Student class) will be called implicitly.there is no LocalStudent object being created, so why is the default constructor of Student being called ?
The default constructor of LocalStudent is also overloaded by the created no-arg constructor containining subjects = null; . So there is no call to the superclass default constructor from the default constructor of LocalStudent.
public class Student { private char year1; public Student(String name, char year){ year1 = year; } public char getYear(){ return year1;
I am writing a program that accepts input from the user, I want default values displayed before the input values.
Java Code:
public surfboards() { surfboardType = "Type not assigned"; shaperName = "Shaper not assigned"; constructionType = "Construction Type not assigned"; surboardSize = 0D; } mh_sh_highlight_all('java');
I can get the output to display as shown below
(THIS IS WHERE I WANT DEFAULT CONSTRUCTOR DISPLAYED. Currently not displayed)
Type not assigned Shaper not assigned Construction Type not assigned 0 Feet
(THIS IS WHERE I WANT DEFAULT CONSTRUCTOR DISPLAYED. Currently not displayed)
input:
Java Code: Enter Surboard Type: test Enter Shaper Name: test Enter Surfboard Construction Medium: test Enter Surfboard Size: 6.5 mh_sh_highlight_all('java');
How do you test a default constructor in one class and then test it in a different class? This is the code for the Person class which has the default constructor. I'm not sure in the PersonTester class how to access this default constructor and how to test it - what I have so far for the second class is also below.
class Person { // Data Members private String name; // The name of this person private int age; // The age of this person private char gender; // The gender of this person
I am having trouble with getting output to be what I want. I can get the output when a user enters their values for month, day and time using a scanner object and they print correctly, but what I want is before they input values, to display the current date. Here is a snippet of what I am working with *these are in two separate files, the first has all the variables etc, the second has the main method.
In one java file:
Java Code:
private int numOfGuests, month, day, year; private GregorianCalendar eventDate = new GregorianCalendar(); public Event() { this("not assigned" , 0, new GregorianCalendar()); } public int getDay() {
[Code] ....
This gives me 0-0-0 as a result instead of current date.
I'm trying to use in the constructor inserts from keyboard and then check whether any of the constructors fields remained empty. Let say my constructor is:
public SomeClass(String a, String b, String c)throws SomeClassException{ if (a == null || b == null || c == null) {throw new SomeClassException("Some message"); // here is the empty test } //...
Thus I prepared method: insertConstruct() as follows:
public static String insertConstruct(){ String lettering = null; Scanner sc = new Scanner(System.in); lettering= sc.nextLine(); return lettering; }
And during creating the new object in some main method I call:
// ... ClassName obj1; obj1 = new ClassName(insertConstruct(),insertConstruct(),insertConstruct()); //...
The problem is not with inserting data but with leaving the field empty. When I pass any field just with keyboards Enter, the empty test doesnt return me any message about it. While it works if I build object with the constructor like:
I am trying to create an empty array that has no assigned length as the amount of elements it needs to hold will be dependent on another value. I then want to use a while loop to assign values to it. Here is an example of what im looking for it doesnt work. Iam trying to do:
int x = 12; int i = 1; int k = 0; int[] factors = {} while (i<x) { if (x%i==0) { factors[k] = i; k++; i++;
I have to create a constructor with eight parameters containing both string and integers.the variables were supposed to be entered by user. but when I try to create an object of the class the IDE post error messages about the constructor.
public class hfiledriver { //the class name is hfile //after the main method I try creating an object of the class //after prompting the user to enter the data hfile hfile= new hfile(firstname, lastname, gender, age, weight, height); }
The one problem in my book was to create a constructor for different shirt features, which I did and ran successfully. Out of curiosity, I also added other methods to see if it would run if the parameters were different from the constructor. It keeps giving me a constructor error. So, my question is, am I able to create a class that uses a constructor with parameters and other methods without errors? I'm guessing there's no reason to since it would be wasted space since the constructor could do it but was just curious if it's possible.
Is everything from the constructor down (in the class) and Shirt.oneShirt (in the main) just a waste of time?
Here's my example:
public class Shirt//class name. { int collarSize;//data field. int sleeveLength;//data field. int pocketNumber;//data field public final static String MATERIAL = "cotton";//final data field for material. public Shirt(int collarSize, int sleeveLength, int pocketNumber)//start of constructor. {
I have a class of Date with a constructor with 3 parameters in it. Those 3 parameters are int data type just to enter month, year, day.
I have another class called Author which has a constructor of Date diedDate; as a parameter passing to the Author constructor.
I was asked to call the Date parameter is null, call the default constructor but I thought for the Date parameter I could only enter something like 0,0,0 instead of typing in null, null, null because null is for String data type isn't it?
what have I done wrong n the following code? I'm trying to create a new instance carte of object Carti using the constructor and then to insert a row into a table created with SQL.The error I'm getting is:
Exception in thread "main" java.lang.NullPointerException at Carti.Carti.InsertCarti(Carti.java:103) at Main.main(Main.java:37) Java Result: 1 BUILD SUCCESSFUL (total time: 28 seconds)
The line Main.main(Main.java:37) is when I try to insert the row. The line Carti.Carti.InsertCarti(Carti.java:103) is when I do the PreparedStatement st = conn.prepareStatement("insert into Carti (Id,titlu" + ", descriere, autor, editie, anPublicare) values (?,?,?,?,?,?)");
public Unit(String code, String name) { enrolStudent(student); this.unitCode = code; this.unitName = name; } public void enrolStudent(Student newStudent){ students = new ArrayList<Student>(); newStudent = new Student(24662496, "Kingsley", " Iwunze"); students.add(newStudent); }
how can I call this enrolStudent() method on this Unit constructor in another class when I create a new Unit. all I need is to enroll students in units when units are created. below is my create unit method.
I am working on a project. It is a shopping cart java program that should be setup with an array size of 5 and increased at increments of 3 if you go over 5 items. When I go over 5 items in increases however it changes the item names to null. See output below.
Here is the actual assignment:
In this exercise you will complete a class that implements a shopping cart as an array of items. The file Item.java contains the definition of a class named Item that models an item one would purchase. An item has a name, price, and quantity (the quantity purchased). The file ShoppingCart.java implements the shopping cart as an array of Item objects.
1.Complete the ShoppingCart class by doing the following:
a.Declare an instance variable cart to be an array of Items and instantiate cart in the constructor to be an array holding 5 Items. b.Fill in the code for the increaseSize method. Your code should be similar to that in the CDCollection class handout but instead of doubling the size just increase it by 3 elements. c.Fill in the code for the addToCart method. This method should add the item to the cart and update the totalPrice instance variable (note this variable takes into account the quantity). d. Add a getTotalPrice() method to return the totalPrice. e..Compile your class.
2.Write a program that simulates shopping. The program should have a loop that continues as long as the user wants to shop. Each time through the loop read in the name, price, and quantity of the item the user wants to add to the cart. After adding an item to the cart, the cart contents should be printed along with a subtotal. After the loop, print a "Please pay ..." message with the total price of the items in the cart. Compile and run this class.
OUTPUT
Enter the name of the item: Apples Enter the unit price: .5 Enter the quantity: 1
Shopping Cart
ItemUnit PriceQuantityTotal Apples$0.501$0.50 Total Price: $0.50 Continue shoppping (y/n)? y Enter the name of the item: Oranges Enter the unit price: .5 Enter the quantity: 1
I am developing shopping cart in which I am storing image in database and retrieving.
When I select any product category from menu. example, I selected Computer then all list of product related to computer will be return i.e productName, Price and image, By using JSON.
this is my json response and output in comment.
success : function(data) { if (data.length != 0) { var d = eval(data); $("#productList").html(""); for ( var key in d) {
[Code] ....
Alternatively I created custom tag to resolve this.Custom tag is working fine in jsp but in java script it saying error raised Unterminated custom tag. I think I used this custom tag in javascript but i am not sure about this error,
custom tag code for image : imgByte = product.getImage().getBytes(1, (int) product.getImage().length()); String encodeimage = new String(Base64.encodeBase64(imgByte)); out.println("<tr><td><img src="data:image/jpeg;base64," +encodeimage + ""/><tr> <td>");
MY Question 1 - How can I use Custom tag in javascript ? Or 2 - How can we extract image from json object, like I did in custom tag .
I created a website using jsp and servlet. I made a shopping cart and got the items to display. But how can i remove the items from the cart? Next to each item is a remove button. When that is pressed the item selected needs to be removed and cart needs to refresh.
I am making a shopping cart web, but some problems I meet about how to calculate the total price
I use ajax in product list web and if I choose one product , it will send the Id that I read from MySql to servlet and use session to save it . and I click the button jump to the cart, the page cart.jsp will read information from session ,and find product information from mysql by id , now my question is where I calculate the total price, servlet or jsp?
I am adding my shopping cart in session like bellow in servlet
HttpSession session = request.getSession(); session.setMaxInactiveInterval(60*30); // 30 minutes if (session.getAttribute("cart") == null){ session.setAttribute("cart", new ShoppingCart()); } cart = session.getAttribute("cart");
I seems if more than one person accesses it from server, if they items in the shopping cart, all the product is added to a single session. I mean if i added 4 items first and other person adds 2 items, second person sees 6 products in his cart. Where am I going wrong?
I am making a shopping cart app in JSP and servlets to bring it all together. Finally.
I have a registration servlet (c1), a registration form jsp (c2), a login jsp (c3). c1 checks if a username is in the database or not.
If the username is not there, then register the user and send them to c3. I want c3 to display a "registration successful" message if a user has just registered successfully and is coming from c1. ELSE, take the user back to c2 with a message which tells them to choose a different username or password etc.
How do I implement the logic of showing a message depending on where a user is coming from ? The servlets and jsps are ready and I only need to add this logic for a custom message. Of course, I could make a JSP for Registration Successful and one for Registration Failure. But, that seems to be unnecessary.
I have a HashMap with multiple values at runtime. In that map one key has empty value , how to avoid this value to add in a list. some code sample is below:
public HashMap getLoop2Map(Map map, String xslFile , int sheetNo){ HashMap hashMap = new HashMap(); try{ ArrayList list = new ArrayList(); System.out.println("-------Map : " +map); list.add(map.values()); //System.out.println("------- boolean : " +val); System.out.println("------List : " +list); }
I do not want to add the empty value in a list ...
result in map
-------Map : {Free Text Entry={}, Mouth / Throat={Free Text Entry={Free Text Entry=<FORMFILENAME>EditChartPhysicalExamText.form </FORMFILENAME><TAG>"<MUSCULOSKELETAL.PE>"</TAG>}, Salivary Glands Condition={Salivary Glands Condition=MouthAttribute}, Examination Overview- Mouth / Throat={Examination Overview- Mouth / Throat=MouthAttribute}, Tonsils={Tonsils=MouthAttribute},
@ManagedBean @SessionScoped public class HelloBean { public void downloadFile() { File file = new File("C:datacontacts.doc"); HttpServletResponse response = (HttpServletResponse)
I've been beavering away with Java for a few months. But as with all languages the String implementation looks designed to trip up even experienced programmers.
My current development gets data from various sources outside my control. When I get a string I want to test if it is empty/null/or whatever. Simple enough one thinks.
But if you search the internet you see everone seems to have a slightly different approach. So what is the best way of determining that a string is not useful to you?
I've had success with this
if(string == null || string.length() == 0)
But I've seen people using methods - not necessarily of String (e.g equals, empty) and regular expressions.
What is the best approach to this considering coding efficiency and/or processing efficiency (accepting you'd have to be processing a lot of strings for the latter to be an issue).
