How To Access Data In Array Of Objects
Apr 23, 2014
I want to keep count of how many students are in my array. the array i made up of objects from other classes. like the class Student how do i do this. i have tried contains but better way it to to a loop to go through the array and determine if each object is a particular type but i don't know how to do this. here is the code
import java.util.*;
import java.util.ArrayList;
public class Driver {
public static void main(String[] args){
/* Comments required
PersonFileReader pfr = new PersonFileReader("person.dat");
ArrayList<Person> testData = pfr.readData();
Database db = new Database(testData);
[Code] .....
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Oct 3, 2014
I've been unable to figure out how to access an objects data from another class. I ended up missing a lesson in java and haven't been able to catch up on this topic on my own through my textbook.
Error: has private access
Code:
public class TestCoffeeDrinker {
public static void main(String[] args) {
Coffee latte = new Coffee("Starbucks Tall Latte", 2.85);
Coffee mocha = new Coffee("Starbucks Grande Mocha", 3.95);
Coffee mcdonalds = new Coffee("McDonalds McCafe", 0.99);
System.out.println(mcdonalds.toString());
[Code]...
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Jul 27, 2014
I am currently working on a project where I need to return data from a database over RMI to a client who requests it. Some of the fields in the Data Object can not be seen by the client so I need to create another object to send over the network instead. The method I use is this...
public static SerializableObject createSerializableObjectFromDataObject(DataObject dataObject){
SerializableObject serializableObject = new SerializableObject();
serializableObject.setField(dataObject.getField());
serializableObject.setAnotherField(dataObject.getAnotherField());
return serializableObject;
}
Is there a better way of doing this? I am creating many subclasses DataObject which all require this static method to be implemented and I can't push it into the superclass because each one needs custom behaviour.
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Apr 1, 2012
I have a doubt about how to design a web application which has their persistent objects in a service layer in a remote server, i mean a business application. So, once we have a web application as a client of this remote business application, how those persistent objects should be mapped in web front?
Should I either pack all jpa annotated classes into the web front application or there is another neat way to do this?
I was intending in copy all persistent classes present in the remote business application into the web app package, i know it's not the best way to get what i need.
What is a more appropriate design for a web application which must get some objects from a remote business application and persist some other objects there?
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Aug 26, 2014
We have implemented SSO based on cookies.
1. user clicks the link in our app (www.app1.com) , cookie set up done (respose.addCookie)
2. request will redirect to (third party software, cant change anything)
3..Here if the SSO enabled, it will redirect to the another URL (www.issues.app1.com) .
4,Have to get the cookie(User details) set in #1 here and validate.
Its working fine .But if we change the www.app1.com to www.abc.com , SSO is not working. We cant change www.issues.app1.com.
How to share the cookie in cross domain across 3 apps ? because middle app , we dont have control over it.
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Mar 29, 2014
I need my java program to insert data into my access database. I get no errors in my code, but it never inserts, deletes the data in my database. Here is my code:
import java.awt.*;
import java.awt.event.*;
import java.sql.*;
public class INS extends Frame implements ActionListener{
Frame f;
Label l1, l2;
TextField t1, t2;
Button b1, b2, b3, b4, b5;
Connection c;
[Code] ....
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May 6, 2014
I have been asked to write a program with 3 classes(an interface, a store and a product class) and I have been going ok until I need to display data on the interface that is held in the product class. At the moment the code will compile fine but when I run the program and try to use the writeOutput() method I get a stack overflow error.
I realise now that it is because of a non-terminating recursive call, however I can not think of a solution on how to fix the problem. And just to clarify, what I am aiming to do is have the MatesTerminal class display the data for name that is stored in the Product class(I have no way of determining which product to display at this time, so I would like to be able to display the data for all three products if possible). Anyway this is what I have so far:
The method from the MatesTerminal Class:
private void writeOutput() {
int productChoice;
Scanner console = new Scanner(System.in);
[Code].....
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Feb 11, 2015
I'm new to java and trying to insert data from a cachedrowset into MS Access database, Below is the error code that I get after running my program.
java.sql.SQLException: Parameter-Set has missing values.
The SQL test table that I am using.
Java Code:
create table book (
TITLE_ID CHAR(3 BYTE)
TITLE_NAME VARCHAR2(40 BYTE)
TYPE VARCHAR2(10 BYTE)
PUB_ID CHAR(3 BYTE)
PAGES NUMBER(38,0)
PRICE NUMBER(5,2)
SALES NUMBER(38,0)
PUBDATE DATE
CONTRACT NUMBER(38,0)
); mh_sh_highlight_all('java');
SQL table values with blanks:
Java Code: TITLE_ID TITLE_NAME TYPE PUB_ID PAGES PRICE SALES PUBDATE CONTRACT
T01Java history P0111121.99 566 01-AUG-001
T02Oracle history P0311419.95 9566 01-APR-981
T03SQL computer P0212239.95 25667 01-SEP-001
T04C++ psychologyP0451112.99 13001 31-MAY-991
T05Python psychologyP041016.95 201440 01-JAN-011
[code]....
Below is the piece of java code that I am using.
Java Code:
public void insertAccessTable(Connection connection, CachedRowSet CRS_insertAccess) throws Exception
{
try
{
RowSetMetaData metaData = (RowSetMetaData)CRS_insertAccess.getMetaData();
ArrayList<ArrayList<String>> TwoDimArrList = new ArrayList<ArrayList<String>>();
TwoDimArrList.add(new ArrayList<String>());
TwoDimArrList.add(new ArrayList<String>());
ArrayList<String> ColArrList = new ArrayList<String>();
for (int column = 1; column <= metaData.getColumnCount(); column++) {
[code]....
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Jul 10, 2014
I have a random access file stream. I have below code I want to written data that is currently pointed by pointer till the end and display that data on System.out Stream but it is not working my code is
//Create a Random Access File
java.io.RandomAccessFile random=new java.io.RandomAccessFile("D:/input.txt","rw");
//Position the pointer to a seek
try {
random.seek(300);
long pointer=random.getFilePointer();
System.out.println("Current Pointer is:"+pointer);
int a;
while((a=random.read())!=-1) {
System.out.println(a);
}
Where am I wrong? Although it is returning actual position of pointer in pointer using
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May 4, 2015
I am creating a read/write, RandomAccessFile that I will use to store several student ID and gpa score. What I don't understand is how I should go about retrieving a particular set of data.
public class ReadWrite {
static Scanner keyboard = new Scanner(System.in);
static String fileName = "Stu.dat";
static RandomAccessFile raf;
public static void main(String [] args) throws FileNotFoundException, IOException {
[Code] .....
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May 11, 2014
I have following methods, which I call from the Event Dispatcher Thread:
public void setTitle(String title) {
Platform.runLater(() -> stage.setTitle(title));}
public String getTitle() {
return stage.getTitle(); // <- Access from outside JFX App Thread ok?}
Is it thread-safe, when the getter-Method just return the value like the example show? Or must I create a Runnable, so stage.getTitle() is called inside the Java Application Thread? How I return the value then?
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Jul 11, 2014
I'm trying to write data for three products to a random access file, but I have a problem. Each product has a code and a price. After writing them to my file, I want to get to the second field or product. I do this by getting the length for each record, and multiplying it by the field number I want to go to. I use the result for the seek() method of the RandomAccessFile object. It is giving me an EOFException, but when I use 0 for the seek method i get the data for the first poduct or field.
Java Code:
public static void main(String[] args) {
final int RECORD_LENGTH = 16;
try(RandomAccessFile productsOutput = new RandomAccessFile("C:UsersalfonsoDesktopBinaryTestRandom.ran", "rw")) {
String[] codes = {"java", "jsps", "txtp"};
double[] prices = {49.5, 19.9, 29.9};
for(int i = 0; i < codes.length; i++) {
[Code] .....
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Mar 7, 2015
I have a class which connects with database and fills object with data. Method looks like this:
//in database class
void getData(anObject a, int id){
//connects with database
a.field1=get...
a.field2=get...
....
//disconnects
}
Now I want to use this method in anObject class, but I can't call it because I don't have created object jet. Is there any way to call this method?
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Apr 29, 2014
How do we cache objects in EJB 2.
My requirement is i need to get data from the database for the first time and retain in cache it throughout the application life.
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May 7, 2014
My problem is that in my program, I have the user input data for one of three product objects, however when I read the data for all three objects, the same data is stored in all of them.
Anyway this is the method from the Interface class:
private void readInput() // the only method in the program that accepts product data from the user {
Store matesStore = new Store();
String name;
int demandRate, productChoice;
double setupCost, unitCost, inventoryCost, sellingPrice;
Scanner console = new Scanner(System.in);
[Code] ....
And here is the method from the Store class:
public static void addData(int option, String newName, int newDemand, double newSetup, double newUnit, double newInventory, double newPrice)
//sets the product data for a particular product {
if (option==1) setData(product1, newName, newDemand, newSetup, newUnit, newInventory, newPrice);
else if (option==2) setData(product2, newName, newDemand, newSetup, newUnit, newInventory, newPrice);
else /*(option==3)*/ setData(product3, newName, newDemand, newSetup, newUnit, newInventory, newPrice);
[Code] ....
The problem I had was with static variables and methods.
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May 8, 2015
I have seen many ways of describing what objects are, one being that objects are a user-defined datatype. However, if objects are datatypes, then what does that make classes? To me, it seems as though classes should be the "types" of data defined by the programmer, and objects should be the specific "values" of that user defined data type. As an example, an integer would be a class, while 1 would be a "value" of that class, i.e. an object. From this point of view, I don't see why a specific number would be a data type... Therefore, why do we say that objects are user defined data types rather than classes?
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Jun 13, 2014
Now I am trying to print the 4 string randomly from string array..where string contains no of words which are splitted from the file....
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Jul 12, 2014
I have written following code.
I want to print all elements in Array to output here is my code
int[][] arr={{12,12,13},
{14,1223,14}};
for(int i=0;i<arr.length;i++)
{
for(int j=0;j<arr.length;j++)
{
System.out.println(arr[i][j]);
}
}
but I am getting following output
12
12
14
1223
how to print all elements of int array?
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Dec 1, 2014
So I have created a array list of pizza toppings, only 4 in total, and each ingredient needs to have a cost property. I'm supposed to access the cost through a get / set method, as the user can create their own pizza and it will total up the cost, but how to.
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Mar 28, 2014
Exercise the Coin class using a driver class in which 5 coins are flipped, as a group, 1024 times. Display the number of times exactly 4 tails are obtained. Display the number of times exactly 5 tails are obtained. Use an array of Coin.
how to put an object into an array?I know how to make a coin class with a Heads and Tails, but I dont know how to make 5 coins all at once.
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Apr 10, 2014
I know the first line below creates an object but the second line creates an array of cars, I'm just not sure how it does that. I can see sportsCar is one object in the array but the others are written in a different way. It seems there should a couple names there instead. Please explain the syntax in this code that's highlighted. I don't know how to make sense of it and I've read through the book where I got it where it explained creating objects.
Auto sportsCar = new Auto("Ferrari", 0, 0.0);
Auto [] cars = {new auto("BMW", 100, 15.0), sportsCar, new Auto()};
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Apr 24, 2014
I have a list of objects in my bean (ex: List<Apple> applies = new ArrayList<Apple>() ).The object has several fields (ex: supplier, color, width, height, breadth, etc.)I want to show this list on the front end. However I also want to allow the user to edit the attributes of the apples.So from the front end I will have like a list of fields where a set of fields is related to a single object in the list.I would also like to add/delete apples.
What first came to my mind is to map every field in the object Apple to a List. For example if Apple has field suppliers and field color then in the bean I would create two Lists, List<String> supplier, and List<String> color.From the front end I would display the contents of these Lists rather then the List<Apple> apples.T
he name of the field would be the same for each set of attributes.On save (form submit) the Lists would be re-populated with the field values (changed or not) and then I would be my Apple objects from the bean before saving in database.However I am not sure if there is something in JSF that can achieve this in a simple way, working only with List<Apple> rather than adding additional Lists.
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Jun 29, 2014
okay,I created a program that demonstrated an array holding a number of objects, each from different classes.the printout I got for the first program ended up being gibberish. when I made the program a second time, I got the correct result.I've been trying to pinpoint the anomaly but I can't seem to find it. So ill try breaking down what I did?
Goal:The purpose of the program was to have a single Class (we'll call the Class 'Animal') to pass the parameters of a previously made method. This method would, amongst other things, call on an array.Further, I would then make subclasses of the Class Animal, and then use them as well to pass the method parameters, thus demonstrating subclasses can be used in place of the super class.
3 of these classes were made purely to as a "place setter". the Classes called "Cat" and "Dog" respectively were created to be subclasses of the Class Animal (with no other code inside them aside from "extends Animal)the 3rd "place setter" called "ClasstoHoldObjects" was created to be the array class (ClasstoHoldObjects itself has no code in it aside from the class name)these are the ones we want.Animal class (which holds the coding meant to be used).Here is the Animal Class
public class Animal {
private ClasstoHoldObjects[] thelist = new ClasstoHoldObjects[5];
int i = 0;
public void add(ClasstoHoldObjects x){
if(i < thelist.length){
[code]....
the print out was this next, im putting THIS line in the array... june_6.Dog@a0dcd9 (and the same by the Cat object).I recognize june6 as the package name.
finally, I erased extra lines as well as comments and simplified class names to make the code more readable. If you want the original, or some class names are a bit off- I could give you the original with all its comments and longer named classes
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Sep 18, 2014
I have a program I want to make (text based, no gui). There is the main class, an Employee class (sort of a template), a CrewMember class, and a Manager class.
I'll put the code for each class an explain the problem I have.
package polymorphism;
import java.util.Random;
public class Start {
public static void main(String[] args) {
Random rand = new Random();
Employee staff[] = new Employee[5];
for(int i = 0; i < staff.length; i++){
[Code] ....
Some of the code is a bit incomplete simply because I ran into the problem. As you can see I made an array in the Start class and it holds objects of Employee type, but create a new instance of either a crew member or a manager, sets their wages, hours, and bonus if applicable. I know if I create an array of a certain type, I can't call upon the subclass' method (Manager in this case) because it has a new method that I added. What I'm trying to do is pretty much call upon the getSalary() method in the Manager class/object, but of course I can't. What way would i be able to do that? I tried looking for some answers. I read about making the superclass abstract and implementing it into the subclasses. Would that be an option?
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Feb 14, 2015
An array has objects with String firstName, String lastName, int ID, char examType('M' or 'F'), and int score. Every object has both Midterm('M') and Final('F'). The array has to be sorted by the first Midterm- 'M' and immediately followed by the Final ('F') of the same person (object). Im having troubles with coming up with a proper algorithm with gettin the Final- 'F' after Midterm for the same person.
Java Code: public static Exam[] collateExams(Exam[] exams) {
Exam [] r = new Exam[10];
r = exams;
int[] position = new int[10];
int index = 0;
for(int i = 0; i < exams.length; i++)
[Code]...
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Oct 27, 2014
I have an assignment where I need to add an interface to an already-created program. I have an array of objects, where each object has a name, price, and priority.
In my original program (which worked), I had all of the objects in 1 class. The professor said that I should split up the name/price/priority into 3 different classes. So what I have is an array that belongs to an interface, and name/price/priority implements. But I am having trouble loading the data into the array (from another class) once I am done with loading name.
Here is what I have so far.
public class Main {
public static void main (String[] args){
Interface[] arr = new Interface[7];
Scanner keyboard = new Scanner(System.in);
System.out.println
[code]....
Line 18 in the ItemName class is giving me an error, and I know it is because arr is of type Interface, and I am trying to assign is a String. But I don't know how to do this. In my original program I was able to do arr[x].getName(); but when I do that in Main, I get errors.
how to assign to an interface array from multiple classes.
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