How To Have Unlimited Object Parameters In Constructor
Nov 21, 2014
I want to create an order system. My Problem is that I want to create it dynamic, with ArrayLists and no fixed Array size.
Basically I have already a User which is able to purchase something.
User a = new User();
Car car = new Car("blue",500);
a.purchase(new Order(new OrderThing(5,car));
This will work!
But I want something like this:
a.purchase(new Order(new orderThing(5,car), new orderThing(2,car), new OrderThing(1,car),...)
Basically I don't know how much OrderThings I want to create before I type in the OrderThings with new Order().
But in java it is before you can construct orderThings you must already know in the constructer how much objects you do want.
Now as im writing this question I got a idea of waiting for an Array of new OrderThing but it don't work. When I write
a.purchase(new Order(new orderThing(5,car), new orderThing(2,car)))
it wants a constructor which is based on Order(orderThing,orderThing)
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Jan 31, 2015
public class TestClass {
public TestClass(String k){System.out.println(k);}
public static void main(String[] args) {
try {
hello();
}
catch(Exception e){System.out.println(e);}
[Code] ....
Explain how to catch block act as constructor with parameter?
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Mar 19, 2014
How to use a constructor with parameters where the user inputs the information? I'm doing a problem where I create a Delivery class that accepts arguments for the year, delivery number within the year, distance code (1 for short distance, 2 for long), and weight of package. The constructor is supposed to also determine the eight digit delivery number (combining the year and delivery number, like 20140054 for this year, package #54).
I know I'm not close to being done but I'm struck on the application with the constructor parameters. If I'm asking the user to input the information, does that mean I have to create a no argument constructor so it will compile? Right now it won't compile because it's asking for the parameters but I can't put them.
This is the class:
public class Delivery {
int year;
int delNum;
double weight;
int code;
[Code] .....
And the error is:
CreateDelivery.java:22: error: constructor Delivery in class Delivery cannot be applied to given types;
Delivery firstDelivery = new Delivery();
^
required: int,int,int,double
found: no arguments
reason: actual and formal argument lists differ in length
1 error
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Feb 28, 2015
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);
}
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Feb 28, 2014
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.
{
[Code]...
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Feb 5, 2015
I have generated wsdl2java code using axis 1.4 . One classes has 2 constructor methods (one default constructor and other one has 2 parameters). Other classes that inherit from one class have the constructor parameters in the wrong order. The schema files is correct as they come from the OTA specification. What should be done to get rid of this ordering problem in constructor
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Aug 2, 2014
So I created this line class and when I try to create Line object with parameters, I don't know how to pass the parameters properly. It has to return two points, so it should be like [(1,2),(5,12)].I tried different things likeLine l1=new Line(Point p1(1,2),Point p2(5,12)); and similar, but nothing worked.
package line;
import java.awt.Point;
public class Line {
private Point p1;
private Point p2;
[code]...
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Oct 9, 2014
How to use the id parameter in my documents entity to download documents from a list of documents. Normally I use ListDataModel and the getRowData method. I would like to know how to achieve the same thing using an ordinary List object.
My list of documents is called List<CountryDocs> selectedDocs;
<h:form>
<p:dataTable value="#{countryDocBean.selectedDocs}" var="docs">
<p:commandLink id="download" value="Download" ajax="false">
<p:fileDownload value="#{countryDocBean.downloadedFile}"
contentDisposition="attachment"/>
[Code] ....
Clicking on the download link calls the following method in my managed bean:
@ManagedBean(name = "countryDocBean")
@SessionScoped
public class CountryDocBean {
private List<CountryDocs> selectedDocs;
public StreamedContent getDownloadedFile() {
[Code] ....
Debugging shows the value for the id is 0 and this results in a NullPointerException. I've tried several methods for grabbing the document id in my backing bean, but no luck yet. I also read about the the ViewParams and ViewAction method but they caused validation errors to do with the <f:metadata> tags. I don't know how to obtain this value using a normal List object.
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Jun 6, 2014
When using Java Code:
Scanner scan = new Scanner(system.in) mh_sh_highlight_all('java');
Why do we put System.in in the constructor? What purpose does it serve and why can't we just not use it?
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Aug 2, 2014
that i started to learn programming and i started with java. so there is a book that i'm on it right now called "Pearson Absolute Java 5th Edition" by Walter Savitch anyway i'm on a project in fifth season which i have to create a class named HotDogStand that operates several hotdog stands distributed throughout town. the whole program is clear. although its so easy to accomplish , my question is more about debugging. so here is the code:
public class HotDogStand
{
private int id; //id number of hotdog stand
private int hotDogsPerDay; //hotdogs sold by one stand
private static int totalHotDogs; //the static value for total hotdogs sold by all the stands
public HotDogStand (int newID, int hotDogsPerDay) {
this.id = newID;
this.hotDogsPerDay = hotDogsPerDay;
totalHotDogs += hotDogsPerDay; //to add the value every time the user uses the constructor (every time the user creates an object)
[code]....
everything works fine. but my question is what if someone use a constructor again? you see if in the main method someone do this after creating the object "stand3":
HotDogStand stand3 = new HotDogStand(3, 43);
stand3 = new HotDogStand(3,40);
i know that it's logical to use setter method but this program doesn't have one. if someone do the thing i wrote above, the calculation of static variable, totalHotDogs will be all wrong. because of totalHotDogs += hotDogsPerDay; it will add another value for the same object. how can i tell the machine to ignore the second (or more) invocation of the constructor for the same object?
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Mar 22, 2014
import java.util.ArrayList;
public class LectureRoom{
private String courseName;
private String roomNumber;
private String Lecturer;
private ArrayList <Student> studentList;
[Code] .....
Question:
Given the following BlueJ class diagram
Lecturer class (same with previous lab, no changes needed)
Student class (same with previous lab, no changes needed)
LectureRoom (changes occurs here)
1. LectureRoom has roomNumber (e.g. A301), courseName (e.g. Java), lecturer (a reference to a Lecturer object), and studentList (a reference to an ArrayList that stores Student object).
2. LectureRoom has a constructor that receives courseName, roomNumber, and Lecturer. The constructor then sets/assign the courseName, roomNumber and Lecturer. This constructor also creates the studentList arraylist object.
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Sep 18, 2014
Its written that every constructor calls its super class constructor. And we know, constructors are called to create an object. Does it mean that if I am creating an object of a class, I am actually creating objects of all its super class???
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Feb 11, 2015
So I want to write a constructor that creates a new object with the data from the array values. I don't know where to start. It's the last method in the code:
public class Measurements {
private double[] values;
private double[] newArray;
private int n; //numberofvalues
private double[] ms;
public Measurements(int max) { //constructor
[code]....
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Mar 8, 2015
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?
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Mar 30, 2014
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 (?,?,?,?,?,?)");
Here is the code (Main and Carti Classes)
import Carti.Carti;
import Imprumut_Carti.Imprumut_Carti;
import Membrii.Membrii;
import static com.sun.org.apache.xalan.internal.lib.ExsltDatetime.date;
import static com.sun.org.apache.xalan.internal.lib.ExsltDatetime.date;
import java.sql.SQLException;
import java.text.DateFormat;
[code]....
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Aug 28, 2014
can we pass private final class object to another class constructor?
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Apr 19, 2014
I was practicing my java skills and came across an exercise in which a non parameter constructor calls a two parameter constructor. I tried a few searches online but they all came back unsuccessful. This is the part I am working on:
public PairOfDice(int val1, int val2) {
// Constructor. Creates a pair of dice that
// are initially showing the values val1 and val2.
die1 = val1; // Assign specified values
die2 = val2; // to the instance variables.
}
public PairOfDice() {
// Constructor that calls two parameter constructor
}
I tried calling the two constructor using the line "this(val1, val2)" but I get an error because val1 and val2 are local variables.
Then I tried to use the same signature: "this(int val1, int val2)" but that didn't work either.
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Mar 28, 2014
Create an equals method that takes an object reference and returns true if the given object equals this object.
Hint: You'll need 'instanceof' and cast to a (Geocache)
So far I have:
public boolean equals(Object O){
if(O instanceof Geocache){
Geocache j=(Geocache) O;
if (this.equals(j)) //I know this is wrong... but I can't figure it out
return true;
}
else return false;
}
I think I have it correct up to the casting but I don't understand what I'm suppose to do with the this.equals(). Also I'm getting an error that I'm not returning a boolean... I get this all the time in other problems. I don't get why since I have to instances of returning booleans in this. "returns true if the given object equals this object" makes no sense to me. I assume the given object, in my case, is 'O'. What is 'this' object referring to?
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Aug 25, 2014
i would like from my bean to redirect after an operation is completed to the page faces/test.xhtml?id=2? Is there a way to do this?
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Mar 1, 2015
I have this JAVA written but I can't get the parameters for the if statements right.
import java.util.Scanner;
public class myFirstJAVA {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Please enter command: ");
String text = input.nextLine();
[Code] ....
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Sep 12, 2014
I'm trying to pass a parmeter to a jsf page from a servlet(i.e. associated with paypal adaptive api), but I keep getting the following error, even though the productType on ProductDetailsVO is a String.
INFO: WARNING: FacesMessage(s) have been enqueued, but may not have been displayed.
sourceId=j_idt2[severity=(ERROR 2), summary=(j_idt2: '45;productType=Sport'
must be a number consisting of one or more digits.), detail=(j_idt2: '45;productType=Sport' must be a number between -2147483648 and 2147483647 Example: 9346)]
Calling JSF page contains:-
returnURL = new URL(new URL(request.getRequestURL().toString()),"pages/paypalpaymentapproved.xhtml?paypalID="+paypalID+";productType=Sport");
response.sendRedirect(returnURL.toString());
[Code] ....
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Jul 16, 2014
My understanding was I could override a method from the superclass, including with different parameters, but when I try to use super. it gives me an error the arguments have to match the superclass. But, if I do that it won't make any sense.
The first code below is the superclass. The issue I'm having is on the second code at lines 7 and 10. The ultimate goal is to make a new class where I'm able to display various packages with or without insurance.
public class Package {
double shippingWeight;
public char shippingMethod;
final char air = 'A';
final char truck = 'T';
final char mail = 'M';
double shippingCost;
[code]....
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Feb 10, 2014
For example, if I have a class called Teacher with the constructor:
public Teacher(double yearsTeaching, boolean isMale, double age)
{
this.yearsTeaching = yearsTeaching;
this.isMale = isMale;
this.age = age;
}
How would I add it to these parameters to my ArrayList in my Tester class?
List<Teacher> teachers = new ArrayList<Teacher>();
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Feb 12, 2014
I have made a class here that has two methods. As you guys can notice, in my two methods that I made, I have listed some arguments in there with parameters. My question is that the variables im using in first method, can they be identical on my second method? Is this ok to do?
public class StudentScore {
private int math;
private int science;
private int calc;
private int history;
private int pe;
[Code] .....
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Jan 11, 2014
In the following Java Code:
public static void f() {
int n = 5;
p(n, 2 * n);
}
public static void p(int a, int b) {
int x = 1;
q(x, a + b);
}
public static void q(int x, int y) {
int z = x + y;
x = 0;
...
} mh_sh_highlight_all('java');
When we write x = 0; that refers to the formal parameter int x and hence it's the formal parameter that changes value. why isn't the value of the actual parameter also changing?
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Mar 7, 2015
Using Eclipse. I have this line of code:
BufferedReader br = new BufferedReader(new InputStreamReader(in));
I want to do something with br in a method that I defined. But Eclipse is complaining about br declared as
public static void Get_Next(String next_line, BufferedReader br) {
How do I make this work?
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