Programming To Registry - Preferences API
Feb 17, 2014
I'm learning Java and came across saving user preferences. As I was learning I also learned about object serialization and File input/output. I've heard that the windows registry can be a problem because it can quickly become a dumping ground for uninstalled programs. So my question is why should I use the Preferences API? and is it really good practice to program to the registry for saving information? I'd also like to be in good standing towards the programs I write so if it is common practice to write to the Registry how exactly would I manage the information that I dump into the Registry?
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Oct 21, 2014
I have a routine that returns a boolean. If any of a series of tests fails, the routine returns false, otherwise it returns true. For example, the routine might test for whether or not an integer is both odd and greater than 99, thus:
public boolean oddAndOld(int x)
{
if (x % 2 == 0)
return false;
if (x < 100)
return false;
return true;
}
I like the above because it suggests that "true" is the condition that applies if the incoming parameter meets all the required criteria. But I've sometimes seen this style used:
public boolean oddAndOld(int x)
{
if (x % 2 == 0)
return false;
if (x < 100)
return false;
else
return true;
}
I like this less because, among other things, if that last criterion is removed, the "else/return true" must be moved up into the immediately preceding test (or else leave some funny whitespace, depending on how you go about removing the departing "if" statement), but it does avoid suggesting that "return true" is hard-coded (that is, it reinforces that "true" is a conditional return value, not inevitable).
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Dec 2, 2014
I am attaching a document which shows the current state of my registry.What I want to know is if I can [safely] delete the JavaSoft folder with all lower subfolders, then re-install jdk1.6/0_31 which, I am told, is the current version being used here by developers.According to others on the development team (not my team), there COULD be something in the registry that is preventing both the installation of java jdk AND its uninstallation.Since I cannot seem to attach any kind of document.
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Jul 30, 2013
My program TestBind0 (code below) tries to find/create a registry and bind an object.
Find/create: it first tests if there is already a registry on that port; if not, then it tries to create one.
The program tries to find/create the registry on ports 40654, 50876, 30321, 33445, 1099, in this order, until it succeeds in both creating the registry and binding the object. Why does TestBind0 throw for each attempt
java.rmi.ConnectException: Connection refused to host: 192.168.1.64; nested exception is:
java.net.ConnectException: Connection refused: connect
at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:601)
at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:198)
at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:184)
at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:322)
[Code] ...
In reg.rebind("TestBind0", obj);even when I have specified -Djava.security.policy==all.policy, with file all.policy in the current dir, containing
grant {
permission java.security.AllPermission;
};
The program is run using command
java -cp bin -Djava.security.policy==all.policy TestBind0
The code:
import java.rmi.*;
import java.rmi.registry.*;
import java.rmi.server.*;
import java.util.*;
public class TestBind0 extends UnicastRemoteObject implements Counter {
private static final long serialVersionUID = 1L;
protected int count;
[Code] ....
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Mar 13, 2015
I was having trouble running some Java programs (not my own) in Windows XP, and in the process I uninstalled and installed JRE versions 6, 7, and 8, one at a time, probably in the order 7, 8, 7, 6, 7. The program that had the original problem only worked in V6, but some other programs stopped working. I went back to V7, and those other programs still didn't work. The message was "the registry refers to a nonexistent java runtime environment installation". The only advice I could find with Web searches was to reinstall the JRE. Needless to say, that didn't work.
So I looked at the registry, and I found that there were still references to V8, which had been uninstalled. The first was
HKEY_CLASSES_ROOTjarfileshellopencommand - (Default) = "C:Program FilesJavajre1.8.0_31binjavaw.exe" -jar "%1" %*
The folder re1.8.0_31 doesn't exist, so I changed it to jre7. That didn't work.
Then I found
HKEY_LOCAL_MACHINESOFTWAREJavaSoftJava Runtime Environment - CurrentVersion = 1.8
I changed this to 1.7, and deleted some following entries such as
HKEY_LOCAL_MACHINESOFTWAREJavaSoftJava Runtime Environment1.8 - JavaHome = C:Program FilesJavajre1.8.0_31
retaining entries such as
HKEY_LOCAL_MACHINESOFTWAREJavaSoftJava Runtime Environment1.7 - JavaHome = C:Program FilesJavajre7
That worked!
So, there is a bug in the installer(s): if you uninstall V8 and install V7, the 'CurrentVersion' isn't set correctly, with the result that the registry points to a non-existent folder. The V8 uninstallation should delete these entries, or the V7 installation should change them.
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Nov 17, 2014
I'm just trying to learn how to cut the IDE out of my programming.I've added C:Program FilesJavajdk1.7.0_55in to the environment variables (path), am navigating to the src folder where my java class exists in cmd prompt, and then typing "javac CaesarCipher.java", but its complaining that it can't find the file.
Is the problem something to do with the relative address of the compiler to the file it needs to run? Just a stab in the dark on my part. Or do I have to add the JRE path as well as the compiler?
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Jan 6, 2014
I find myself asking these two questions because I see them as relating. First question is; I always write
Java Code: f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); mh_sh_highlight_all('java');
(where f is a JFrame object)
to set the close for the JFrame. What I don't get about this is what is going on in the parenthesis. I looked in the Java Documentation, and it says an int goes inside. In that case, I don't really get what the word JFrame is doing there. Overall, please explain what is inside the parenthesis of that line and why it has to be there.The second question is a generic question. I notice a lot of times an object will be created, and as its parameter, you will have to instantiate an object. an example would be
Java Code: Class f = new Class(new Object) mh_sh_highlight_all('java');
What does it mean when an object gets created inside of a new object? Why is putting Java Code: new Object mh_sh_highlight_all('java');
ever necessary when concerning the two parenthesis?
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Apr 15, 2015
The goal is as follows: Write a UDP 'CompressionServer' that will take input from the user until it sees a "magic string" at which time it will create a compressed and uncompressed version of the file in the file system.
So, I need to integrate the following "Zip" code in to my UDP server code (which already creates the uncompressed file)... That is where I am stuck at now. My first few attempts had the Zip code after I write to "fout" but that failed to create a ZIP file.
I guess the main point here is what are the key pieces of the ZIP code that I should include and what would be the best spot to place them in my server code...
Zip Code:
import java.io.*;
import java.util.zip.*;
public class Zip {
static final int BUFFER = 2048;
public static void main (String argv[]) {
try {
String fileInput = argv[0];
String fileOutput = argv[1];
[Code] ....
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Nov 25, 2014
class triangle
{
public static void main (String[] args)
{
System.out.println("Provide three side lengths - 000 to terminate.");
int a = In.getInt();
int b = In.getInt();
int c = In.getInt();
[code]....
My problem is that when I enter 5,2,5 it should be isosceles and acute but it comes out as isosceles and obtuse, and when I type 5,5,5 it comes out equilateral and right. The only one that works is if I enter 3,5,4 it will come out as scalene and right. I been at this for a while and my math looks correct.
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May 3, 2014
I'm having problems programming the LightsOut game. I made a 5*5 matrix and filled it in with 1's and 0's, where 1 means on and 0 is off, they should be placed randomly. The player can choose a field, for example "A2", and the matrix should change according to the input. My problems are how can I choose a field ? How can I display the new matrix after playing the first step and so on?
PS: I'm using the console because I'm still not good with JOptionPane commands.This is my code for the Game:
public class TestLightsOut {
public static void main(String[] args) {
// TODO Auto-generated method stub
int[][] blocks = new int[5][5];
String[] letters = { "A", "B", "C", "D", "E" };
String[] numbers = { " ", " ", " ", " ", "1 ", "2 ", "3 ", "4 ", "5 " };
String[] line = { " ", " ", "_", "_", "_", "_", "_", "_", "_",
"_", "_", "_", "_" };
[code]...
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Feb 21, 2014
What is difference between algorithm and programming?How to develope algorithm knowledge?
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Apr 3, 2014
We are working with Java and Eclipse..One of the assignments asks to "Write an application that determines the number of coins in a jar and prints out the total in dollars and cents. Read integer values that represents the number of quarters, dimes, nickels and pennies. Use a currency formatter to print the output."
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May 1, 2014
I would like to bring a project in java program written by me, that interfaces with a fingerprint reader (already purchased, the reader U.are.U 4000b) and as I'm using fingerprint sdk sdk's Griaule.
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Oct 13, 2014
I am looking to program a simple genetic algorithm in Java but where to start.
" In a computer language of your choice, implement a simple genetic algorithm (GA). That is, write code for a generational GA which uses a binary encoding, tournament selection, single-point crossover and bit-wise mutation" ....
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Dec 29, 2014
what is meaning of Open Source in programming lenguages?
I want to ask this question reagrding this context that if some company or some products that says "This is open source" all codes are available Then it it mean..
1)We can reuse,re produce,distribute this code,modify and sell it for commercial purpose?
I know there is license also attach with a OpenSource.
But What exactly meaning of OpenSource?
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May 12, 2014
Which of these is not a real differentiator for programming languages:
a) Object-oriented / Process-Oriented
b) Interactive / Automated
c) Interpreted / Compiled
d) Strongly-Typed / Weakly-Typed
e) All of the above
f) B and C
g) B and D
Almost all support OOP, Interactive/Automated, Interpreted/Compiled but not sure about Strongly typed/Weakly typed.
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Aug 30, 2014
Use Java to write and run a simple console-window program for checking passwords. The program must satisfy the following requirements:
-When the program runs, it should first print its name, e.g., Password Checker
-The program should next prompt the user to enter a username, e.g.,
Please enter your username:
-The program should next prompt the user to enter a password, e.g., Please enter your password:
- If the user enters a correct password, i.e., one that matches an internal secret password, the program responds. You are approved by access control!, and quits.
-If the user enters an incorrect password, the program responds
Try again:
-If the user enters a correct password matching the secret one, the program responds. You are approved by access control!, and quits.
-If the user enters an incorrect password, the program responds
package class1;
import java.util.Scanner;
public class class1 {
public static void main(String[] args) {
// TODO Auto-generated method stub
[code]....
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Sep 2, 2014
i was reading my book when in a code,it used accept(),but it did'nt talk about it.would you explain to me where to use accept().(the chapter was about socket programming)
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Nov 17, 2014
I am having some trouble programming the Game of Life algorithm.
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Feb 12, 2015
can we use java programming for image processing. if yes then how do we do it?
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Jan 29, 2015
I'm reading a book titled 'Intro to Java Programming'. I understand all the Main Method stuff. I'm now reading a chapter that talks about event driven programming. I know how to do this in VBA and in C#, ut I can't figure out how this works in Java. Here's the sample code that I'm trying to run.
import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
[code]....
I'm using Net Beans IDE. When I paste that code into the IDE, I get all kinds of errors. Also, since there is no Main, I don't know how this is supposed to run. Java needs a Main Method for everything, I think. Does the Main call some kind of class?
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Apr 7, 2014
I have written a java code to transfer files from one server to another using the concept of socket programming. I got the codes from another java forum that meet my requirements. The program is said to transfer large sized files (like .mkv , .mprg movies) from one machine to another and can be used to transfer files of all formats. But after running the codes I found that the program is not able to transfer large sized files such as movies and even pdf of sizes 80mb or 111mb. When i transfer small sized files, it gets transferred and the output shows that. You can run the codes and observe it. But when i try to transfer large sized files, the program goes on running for hours. The large sized files are not getting transferred. The program has used bytebuffer but still this error occurs. The codes are as follows (I got them from this site [URL] ....)
**ClientMain.java**
import java.io.IOException;
import java.net.Socket;
public class ClientMain
{
private DirectoryTxr transmitter = null;
Socket clientSocket = null;
[Code] .....
1. ClientMain.java and DirectoryTxr.java are the two classes under client application.
2. ServerMain.java and DirectoryRcr.java are the two classes under Server application.
3. run the ClientMain.java and ServerMain.java simultaneously
Also specify the source directory, destination directory and host address of the machine in which server is running in the ClientMain.java (as per your computer). Here we are not specifying source file, instead a source directory or folder is specifying. So the entire files of source directory will be transferred.
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Jan 13, 2014
I am new to java. I want to create a socket that can serve all the network protocols. Can we make such type of socket in java.
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Apr 4, 2014
1. Modify the following class so that the two instance variables are private, there is a constructor that accepts both the player's name and sport and there are get and a set methods for each instance variable:
public class Player {
String name;
String sport;
}
2. You can pass an instance of this class to the JLabel constructor if you want to display text in the label.Select one:
a. myLabel
b. myText
c. String
d. JTextField
e. JLabelText
how to start making this work?cause i am not familiar with the terms here and want to complete this program and I am new to java programming?
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Oct 13, 2014
I have written this program but I am seeing error when I compile this program ( javac TestArithmetic.java).
1)TestArithmetic.java:26 cannot find symbol
2)symbol: class Arithmetic
3)location: class TestArithmetic
4) Arithmetic ar = new Arithmetic(x1,x2,x3);
1)TestArithmetic.java:26 cannot find symbol
2)symbol: class Arithmetic
3)location: class TestArithmetic
4) Arithmetic ar = new Arithmetic(x1,x2,x3);
2 errors.
Code :
import java.util.*;
class TestArithmetic {
public static void main (String[] args){
float number;
Scanner console= new Scanner (System.in);
System.out.println("Enter first number");
[Code] .....
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Sep 10, 2014
exception in thread main java.lang.nullpointerexception code 45 and code 116
the lines are highlighted and no the code tags did not show up when I uploaded the file.
I typed '[code]' below:
Java Code: /**
This program demostrates rainfall for a year
*/
[Code].....
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