Modify Values In Fields In Serializable Object Using Objects Set Methods Java
Dec 10, 2014
This program is basically complete. It compiles and runs. It is a college course assignment that I pretty much completed but for the last part in which I'm suppose to change the values of all fields and display the modified values using a toString method. Modifying the values of the fields is where I am stuck. I don't think I need to create a new text data file to do this. The instructor only asked that all the values of fields be changed and this was the last part of the assignment so I don't think it involves creating additional ObjectOutputStream and ObjectInputStream objects. I'm getting a NullPointerException error on line 161.Here is the code. I'm also including the input data file.
//create program so that objects of class can be serialized, implements interface Serialiable
//create constructor with 4 parameters with accompanying get and set methods, Override toString method
//create text file with 5 records, create Scanner object,ObjectOutputStream, and ObjectInputStream
//create new ItemRecord object, change values of all fields in ItemRecord object using object's set methods
//modify ItemRecord object using toString method
[hightlight =Java]import java.io.Serializable;
public class ItemRecord implements Serializable
[Code] .....
This is the error message:
----jGRASP exec: java ItemRecordReport
Item Cost Quantity Description
Number
A100 $ 99.99 10 Canon PowerShot-135
A200 $149.99 50 Panasonic-Lumix T55
A300 $349.99 20 Nikon- D3200 DSRL
A400 $280.99 30 Sony- DSC-W800
A500 $ 97.99 20 Samsung- WB35F
Exception in thread "main" java.lang.NullPointerException
at ItemRecordReport.main(ItemRecordReport.java:161)
----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.
Here is the data file:
A100 99.99 10 Canon PowerShot-135
A200 149.99 50 Panasonic-Lumix T55
A300 349.99 20 Nikon- D3200 DSRL
A400 280.99 30 Sony- DSC-W800
A500 97.99 20 Samsung- WB35F
Here is the data file for the modified field values.
B100 98.00 10 ABC1010
B200 97.00 15 DEF1020
B300 96.00 10 GHI1030
B400 95.00 05 JKL1040
B500 94.00 01 MNO1050
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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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Now the problem arises , while inside this method i am able to read all the data i need from the user object. At the end of the method i save the reference of this object in a new User object defined in the second JFrame ,because i need it later on.
But soon as this method finishes , for some reason my reference to the object becomes null , and i cant use it later on.
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1package de.kugihan.dictionaryformids.dictdconv;
2
3import java.io.FileOutputStream;
4import java.io.IOException;
5import java.io.OutputStreamWriter;
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[code]....
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Sep 23, 2014
class MultipleReturn {
int getInt() {
int returnVal = 10;
try {
String[] students = {"Harry", "Paul"};
//System.out.println(students[5]); //if i remove comment
[Code] .....
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I am trying to find a concise way to write the sort methods for my class. I am supposed to make a program that can sort objects by a number of fields: year, rank, artist and title.
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And I am trying to use the custom comparator for my sort methods. However for some reason, the sortingBy variable fails to recognize any of the enum types.
Whenever I try to set the sortingBy variable equal to one of them, for example:
Java Code:
private Order sortingBy = Year; mh_sh_highlight_all('java');
I get a "Year cannot be resolved to a variable" error.
What I want to be able to do is make it so every time a specific method is called, say, for example sortTitle(), sortingBy will change to Title, then the SongComparator will sort using the case Title.
Is it possible to do this? I can't figure out how to modify SongComparator's object variables that way.
Java Code:
import java.util.Comparator;
public class SongComparator implements Comparator<Song> {
public enum Order {Year, Rank, Artist, Title}
public Order sortingBy;
[Code] .....
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Jul 31, 2014
I'm facing a problem in below scenario:
List lst = tDAO.executeReport();
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Oct 26, 2014
I am trying to grab a graphical object from an arraylist, and reposition its coordinates on a Jframe when adding it. My program of course deals with strings, and once it sees specific words in my console, some method is called that adds, removes, or otherwises modifies certain objects on screen.
Here I want to say something like move(object[1],xpos,ypos) which will move a certain object from a specified point in the array, and move it to new x and y positions on the JFrame. I use a different class that extends a graphics program, so when I say add(something,x,y) it draws the object onscreen where I want it. These are some relevant, though incomplete, methods that should move an object already painted on screen:
Console class
Java Code:
public void doMoveCommand(String cmd, String arg, String xpos, String ypos) {
int x = Integer.parseInt(xpos);
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freeCommand();
[Code] ....
When I say makepos(whatever) I am getting a arraylist out of bounds exception. How I might be able to accomplish moving objects already on screen?
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Mar 12, 2015
A blood clinic has hired a team of software developers to build a custom application to track patients. The clinic needs to keep a record of each patient and his or her blood data. Ultimately, they want all of the information stored in a database. As a starting point, the development team leader informs the team that the application has to have a set of core classes that represent the “real-world” entities the program needs to deal with. As a developer on the team, your job is to build a Patient class along with a BloodData class so that each Patient contains a BloodData object. This principle is known as “composition.”
Building the Framework Begin by creating a public Java class named PatientBuilder that contains a main method. Then, in the same file, create a non-public class named Patient and another named BloodType. Save the file as PatientBuilder.java. Note: If this was a real development project, you would put each class into it’s own file and put the files in the same folder. By combining them all into one file, we avoid having to submit three separate files, making it easier to keep all your work in one place.The BloodData Class This class should hold all of the attributes to hold the data the clinic needs for a given patient’s blood. Implement the following capabilities to accomplish this objective:
• Create a field to hold a blood type. The four possible blood types are O, A,B, and AB. For this project, you can simply define the field as a String.
• Create a field to hold the Rh factor. The two possible Rh factors are + and –.For this project, you can simply define the field as a String.
• Create getter and setter methods for both fields.
• Create a default constructor that sets the fields to “O” and “+”
• Create an overloaded constructor that accepts two parameters – one for a proposed blood type, and another for a proposed Rh. The constructor
should call the set methods and pass these parameter variables in to them.The Patient Class This class should hold all of the attributes to hold the data the clinic needs for a given patient’s blood. Implement the following capabilities to accomplish this objective:
• Create a field to hold an ID number along with get and set methods.
• Create a field to hold the patient’s age along with get and set methods.
• Create a field to hold the BloodData for a Patient. When declaring the field, initialize it by instantiating a BloodData object. Create get and set methods.
• Create a default constructor that sets the ID to “0”, age to 0, blood type of the BloodData object to “O”, and Rh value of the BloodData object to “+”.
• Create an overloaded constructor that accepts the following parameters: ID,age, blood type, and Rh. The constructor should call the set methods for the field associated with each parameter.The PatientBuilder Class.This class should contain the main method from which the program runs. In that method, implement the following functionality:• Ask the user for the ID, age, blood type, and Rh factor of a Patient.
• Create a Patient object, passing all of the data obtained from the user into the object.
• Write the code necessary to display the ID, age, blood type, and Rh factor of the Patient by calling the appropriate get methods of the object.
MY CODE ( which does not compile since it is wrong...)
import java.util.Scanner;
public class PatientBuilder
{
public static void main(String[] args){
String patientID;
int patientAge;
String patientRh;
String patientBlood;
[code].....
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Mar 31, 2014
I have a design scenario here which is quite interesting and complex. I have a Java class structure as follows,
class A
{
class B;
innerClass B
{
List<class C> listofC;
innerClass C
{
String attribute1;
String attribute2; // Their getter setters
}
}
}
So I have this as an API. Now my challenge is that I need to add one more property to inner class C. i.e attribute3 in innerClass C. I need to do this without disturbing the code in class A by extending these classes or writing a new wrapper, so I can use class C with new properties .
I hope this should be achievable through any design pattern either at runtime or design time.
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The problem is, that at the beginning (when user runs a program), I want to get information (which is actually values for my GUI components ) from Database. It could, for example, create another DatabaseManager and connect to the Database to get information, but it is okay to have two objects?
I was also thinking about sending same DatabaseManager object through InputManager to Navigation, but it seems strange for me to have two objects, which can interact with each other in both directions(Class A has instance of Class B, and Class B has instance of Class A). Is there anything bad this can do?
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Jan 29, 2014
"What happens if you modify the common object references in these lists, myArrList and urArrList ? We have 2 cases here: In the first one, you reassign the object reference using either of the lists. In this case, the value in the second list will remain unchanged.In the second case, you modify the internals of any of the common list elements - in this case, the change will be reflected in both lists."
I have written the following code, which tests the first case mentioned above, and i get the output as expected: myarrList remains unchanged. How can i test the second case ? My thoughts are ....'second case is untestable the following code, because String is immutable. I need to use StringBuilder or something else to write code for test of second case mentioned'.
ArrayList<String> myarrList = new ArrayList<>();
myarrList.add("one");
myarrList.add("two");
ArrayList<String> urarrList = new ArrayList<>();
urarrList.add("three");
urarrList.add("four");
System.out.println("ArrayLists setup");
[code]....
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I am trying to create a method for my "ticketmachine" object that counts ticket objects in an arraylist of "ticket" objects with a specified field "route". The method works if i change the field type of the ticket class to public, however according to the homework task "route" of the ticket class needs to remain a private field.
Here is my code for the method.
public int countTickets(String route) //HAD TO CHANGE Ticket class FIELD "ROUTE" TO PUBLIC!!!!
{
int index = 0; //returns the number of Ticket objects in the machine with the specified "route".
int ticketCounter = 0;
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[Code] ....
Is my general approach to the problem wrong? also is there a way to access a private field?
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This worked fine when I just put all 20 fields through the constructor and set them as fields under all the constants. But I realized that if I wanted to make an instance of this Enum class, I'd have to enter in all 20 fields when they are all a set of Objects with unique values. So I then put them as fields under their own respective constant to make it easier to create instances of this enum. But now my methods don't work.
A) I don't really understand why they don't work anymore?
B) Is there a way to fix it without putting all the methods under each constant?
Example:
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AAA {
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BBB {
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CCC {
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DDD {
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b) incrementing into the next hour and
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[code]....
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[Code] ....
I have assembled this code below that has a void method which will creat a new object. Problem I encounter is that in
Create_object(person_one);
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[Code] ....
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public class MonsterGame{
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[Code] ....
I understand that there need to be instances of objects to call methods, but is that not the case here? the Monster objects are have already been created, no? Do I need to create an index for the array? is the for loop not enough?
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{
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[Code] .....
The getAccountNumber method works but writeCheck is throwing an error. I tried creating a method in the superclass and overriding it in the subclasses but with no success.
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[Code] ......
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