Storing Data Of Particular Class In Files
Jul 29, 2014
I need to store the data of a bunch of objects of a particular class in files in a predefined directory. Later, I want to get all the files from the directory and turn them into the objects again. Ideally, I'd like to have one file per object and have the files be human-readable and editable without too much difficulty. The class used by the objects will likely be subject to change in the future, as well. To keep things simple, all the data members are either primitives, Strings, or arrays of them. What is the best library/API to use to deal with this situation? Or should I write my own classes for these operations?
I read into serialization, but I read that it doesn't deal well with classes that are frequently modified. I also found articles on Preferences, but none of the ones I saw seem to explain how to best handle reading and writing to and from multiple objects, especially when I don't know a prior all the objects that were written to disk.
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Mar 26, 2014
I've the following requirement. A centralized server needs to be established using java code. The server's responsibility is receiving the status of the each client machine as a XML file and storing it in the server's disk space. The client machine also runs the java code to send the status to the server as an XML file in a daily basis. I've planned to create a SOAP webservice in server machine and client machine will invoke the soap webservice to send the status. Do I have to establish any FTP server for storing the XML files? Is there any other better solution for this requirement?
Do I have to establish any FTP server for storing the XML files?
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Jul 22, 2014
I've sample code of jsp and servlets. Below is my code.
Index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action="AnnotationServlet">
[code]....
Now I want to store those username and age(in .html) somewhere and I want those information in welcome.jsp. Now, I'm storing all those in session itself(In doGet method(servlet)).
2 Doubt) Also, when I get the session in servlet HttpSession session = request.getSession(); line No. 27. The session value is org. apache. catalina. session. StandardSessionFacade@69a8bf4f...I'm expecting that session is to be empty. Because, I dint store anything until that line.
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Dec 4, 2014
I have created this project and want to be able to add new members to my members arraylist, store the input in a .txt file and load the new members after closing and opening the program.
[URL] .....
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Aug 6, 2014
I am working on my second javafx program and I am getting confused. The program that I am writing is a payroll calculator. A secondary window opens at the start of the program where the user first enters the number of employees and clicks submit to save the number and to close this window. Then, the user begins to enters the employee information (first name, last name, pay rate and hours worked) when the user clicks the NextEmp button, I want the data in the text fields to be entered into arrays for later use, then clear the fields for the next use. I am running into 2 issues. The first is the close event for the secondary window that pops up. I cannot figure out the syntax. The second issue that I am running into is the loop to store the data into the arrays. I believe I am getting the text field data correctly, but I cannot figure out how to stop the loop until the NextEmp button is pressed again.
import javafx.application.Application;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.scene.input.KeyCode;
[Code] .....
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Nov 16, 2014
I have declared an array list that will store data type of 1 Character and 2 integer. The data that will be store in this list is
1. A = {0 3}
2. B = {0 5}
3. C = {0 3}
4. D = {0 3}
5. E = {0 5}
6. F = {0 6}
Now here the alphabets are routers and integers are there con1 and con2 respectively. I have a set of router={ A,B,C,D,E,F}.
Step 1:I have to subtract con1 from con2 i.e. (3-0) of all the routers and
Step 2: then put the router having largest value in new set 1 and
Step 3: then this router will be subtract from the router set.
Step 4:then again I have to repeat the step 1 until the value of routers become <= 1.
Now what I did is I defined 3 arrays first is String array that stores names of routers, 2nd array that stores the first value and 3rd array that stores the second value. I can find the largest value but how to store the name of router against the largest value in the set.
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Mar 7, 2015
I've spent almost 3 hours on googling about java beans and where it is usable. What I've figured out is that a bean has a public non-arg constructor, properties and getters/setters to manipulate them. I also know that a bean contains no logic, only fields. However, I don't fully understand why I need to use beans instead of normal classes even if a class can do the same things like a bean? Are beans used to store data or what?
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Jun 2, 2014
My assignment was to create a class and then write a program that uses the methods of the class I created. All the output is correct except for the Question # Missed. It prints [I@1dd0fe7. The wrong question numbers have to be stored into an array and that array printed. I've tried using a for loop to print, rearranging the code, setting the code to how I did in the other methods. I either get this [I@1dd0fe7 -or- a bunch of 0's. I'm not sure if I am calling the method incorrectly, or just do not have the correct set-up to print the array, or if I am just not grabbing the ones that are incorrect.
public class DriverExam {
// Fields
private boolean result;
private int testTotal;
private int numWrong;
private int [] numMissed;
private char [] answerKey;
[Code] ....
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Dec 4, 2014
I have created this project and want to be able to add new members to my members arraylist, store the input in a .txt file and load the new members after closing and opening the program.
[URL] ....
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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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Aug 26, 2014
I'm new to java. I have a Product class with getters and setters.
E.g. setProdType & getProdType
I want to store the values from a file into that
StringTokenizer token = new StringTokenizer(line,"**");
while(token.hasMoreElements()) {
int p.setProdType = Integer.parseInt(token.nextElement().toString());
}
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Apr 5, 2014
I am suppose to display some information from some text files I tried to do that but the output gives me information from one text file and not information from all text files.
public static void main(String args[]) throws IOException {
String occupations;
double unemployRate_By_Occupations_2008;
double unemployRate_By_Occupations_2009;
double unemployRate_By_Occupations_2010;
//declare the file object and open the file "occupations.txt";
File myFile = new File("occupations.txt");
[code]....
The first text file is:
2.5
3.3
2.6
3.1
2.4
2.7
2.6
[code]....
the second text file is:
4.6
5.7
5.2
6.9
4.5
4.3
[code]....
The third text file is :
4.8
5.6
5.2
6.2
4.6
4.6
2.7
[code]....
Reason for edit:: Renamed title to be more descriptive, added code tags, and removed font formatting
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Feb 13, 2015
how can I extract data from two different files but produce one output. For example, the first three columns are from text_file_1 and the last column (the last foruth column of the output) is from text_file_2.
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Apr 13, 2014
I am trying to write a program that read from a csv file called matches.csv.
A single football match can end with a win or a draw: in first case the winner team get 3 points and the loser none, in the second case of draw each of the two teams get 1 point.
For example, the first line of the file matches.txt is as follow:
In the file it contains the following data.
17/08/2013ArsenalAston Villa13
24/08/2013Aston VillaLiverpool01
This means that a match has been played on the 17/08/2013 where Arsenal scored 1 goal while Aston Villa 3 goals: thus Arsenal got 0 points while Aston Villa 3 points.
How can I structure my output to make it make it read
Position Team Played Points
1 Aston Villa 2 3
2 Liverpool 1 3
3 Arsenal 1 0
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Teams {
public static void main(String[] args) {
String fileName = "matches.csv";
File file = new File(fileName);
[code]....
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Apr 14, 2014
I am trying to write a program that read from a csv file called matches.csv.
A single football match can end with a win or a draw: in first case the winner team get 3 points and the loser none, in the second case of draw each of the two teams get 1 point.
For example, the first line of the file matches.txt is as follow:
In the file it contains the following data.
17/08/2013 Arsenal Aston Villa 1 3
24/08/2013 Aston Villa Liverpool 0 1
This means that a match has been played on the 17/08/2013 where Arsenal scored 1 goal while Aston Villa 3 goals: thus Arsenal got 0 points while Aston Villa 3 points.
How can I structure my output to make it make it read
Position Team Played Points
1 Aston Villa 2 3
2 Liverpool 1 3
3 Arsenal 1 0
Java Code:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Teams
{
public static void main(String[] args)
{
String fileName = "matches.csv";
[Code] ....
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Feb 26, 2015
I have written a program (DOM Parser) that parses data from a XMl File. I would like to create an individual file with the corresponding name for each set of data parsed from the xml document. If the parsed output is Single, Double, Triple, I would like to create an individual xml file (Single.xml, Double.xml, Triple.xml)with those corresponding names. How do I create the xml files and give each file the name of my parsed data output?
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
[code]....
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Oct 27, 2014
I want to create an application wich can handle xml files ( display xml files's data on a html page) + insert those data into an oracle database.
I'm new to that, it a project for my internship. wich API is the most appropriate for that ( Jdom or Xstream or other), wich framework i can use ( there is only 3 IHM : connexion, upload file, display data, confirmation insertion data)?
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Mar 21, 2015
I have my code in 3 different files using encapsulation (Data hiding) and i have 1 problem at the very end of my code in my if and else statement (very bottom) when trying to call the classes from the other 2 documents. I will put the code in 1st document to 3rd document.
// FIRST DOCUMENT
public class CollegeCourse { //class name
//variables
String deptName;
int courseNum;
int credits = 3;
double fee;
[Code] ....
UPDATE: error message is
UseCourse.java:24: error: cannot find symbol
LabCourse lc = new LabCourse(department, course, Credits);
^
symbol: variable department
location: class UseCourse
UseCourse.java:24: error: cannot find symbol
LabCourse lc = new LabCourse(department, course, Credits);
[Code] ....
4 errors
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Feb 26, 2015
I have written a program (DOM Parser) that parses data from a XMl File. I would like to create an individual file with the corresponding name for each set of data parsed from the xml document. If the parsed output is Single, Double, Triple, I would like to create an individual xml file (Single.xml, Double.xml, Triple.xml)with those corresponding names. How do I create the xml files and give each file the name of my parsed data output?
import java.io.IOException;import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;import org.w3c.dom.Element;
[Code] ....
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Oct 25, 2014
I managed to retrieve data, and set data in my own ways in which I like. But my problem is, if the file does not contain anything (fully empty), when I try to use my
set("", "");
method, it only sets the last one that is called.
Example:
set("section1", "section1Item");
set("section2", "section2Item");
set("section3", "section3Item");
Only section3 would get set, and not the others.
Otherwise, if the file contained a section already, then each section (section1, section2, section3) would get set.
Here's how I set the data to the file:
public static void set(String section, String data) {
files.openFileWriter();
files.file.delete();
reCreateFile();
String beforeItem = section + ":" + files.dataList.get(section);
[code]....
And here is how a retrieve the data and set them to my arraylist/hashmap:
public void getData() {
String line = null;
openFileReader();
StringBuffer sb = new StringBuffer();
[code]....
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May 4, 2015
How can I Cache the data I'm reading from a collection of text files in a directory using a TreeMap? Currently my program reads the data from several text files in a directory and the saves that information in a text file called output.txt. I would like to cache this data in order to use it later. How can I do this using the TreeMap Class? These are the keys,values: TreeMap The data I'd like to Cache is (date from the file, time of the file, current time).
import java.io.*;
public class CacheData {
public static void main(String[] args) throws IOException {
String target_dir = "C:Files";
String output = "C:Filesoutput.txt";
File dir = new File(target_dir);
File[] files = dir.listFiles();
[Code] ....
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May 15, 2007
Is it possible to generate a javadoc from .class files?
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Oct 12, 2013
I need to process 10000 xml files and verify and insert the data into database. I am loading all the files in the file object and iterating one by one. I am getting the memory issue. How to handle this?
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Apr 3, 2014
The problem is what to do when the source file for a class gets too big ( a judgment call for sure). Is it possible for one class to be defined in multiple files and if so how do you do it, and is it good practice?
I do see ways to refactor into a base class or move code into a helper class but sometimes the abstraction is cleaner as a single class that does a lot of stuff. My problem is how to organize a BIG class?
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Mar 30, 2015
I'm writing a custom class loader to load some .jar file
public class IQJarClassLoader extends ClassLoader {
private String jarFile = "json-simple-1.1.1.jar";
private Hashtable classes = new Hashtable();
public IQJarClassLoader() {
super(IQJarClassLoader.class.getClassLoader());
[Code] .....
I receive this exception :
Exception in thread "main" java.lang.ClassCastException: org.json.simple.parser.JSONParser cannot be cast to org.json.simple.parser.JSONParser
Everytime, because i don't cast. Casting an object to a class with the same name loaded by different classloaders is no different than trying to cast.
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Feb 17, 2015
I want to search for files using wildcards. After a lot of googling I found [URL] ..... I downloaded the .java files and put them in the same directory as my own java file. but now I don't know, how to include this java file.
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