RMI :: Find / Create A Registry And Binding Object
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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Apr 9, 2014
Task:The main method of the class Things below creates an object called printer deriving from the class PrintingClass and uses that object to print text. Your task is to write the PrintingClass class.
Program to complete:
import java.util.Scanner;
public class Things {
public static void main(String args[]) {
String characterString;
Scanner reader = new Scanner(System.in);
PrintingClass printer = new PrintingClass();
System.out.print("Type in the character string for printing: ");
characterString = reader.nextLine();
printer.Print(characterString);
}
}
// Write the missing class here
Note: In this exercise the solution is part of a conversion unit where many classes have been declared. Because of this the classes are not declared as public using the public attribute.
Example output
Type in the character string for printing: John Doe
John Doe
My Class:
class PrintingClass {
public void print(){
System.out.println(characterString);
}
}
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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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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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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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Feb 19, 2015
I have created an object of arrays, and i need to find the max value...
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Jun 17, 2014
I'm not sure if I am doing something wrong or what but I can not get this to run
it gives me an error on lines everytime there is an object ch as line 3. with error "cannot find symbol"
public class EmployeeDemo {
public static void main(String[] args) {
Employee e1 = new Employee();
e1.name = "John";
e1.ssn = "555-12-345";
[Code] ....
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Sep 9, 2014
I'm trying to make an array of objects, which I then initialize using objects that I have already created. I have main class, a secondary "Other" class, and a third "Other2" class. In the first Other class, I create three objects of the Other2 class, an object array of the type Other2 , and I then try to add the three objects to the object array, which results in the errors:cannot find symbol: class objectArray, ] expected, identifier expected
here is my code:
Other class
public class Other
{
Other2 object1 = new Other2();
Other2 object2 = new Other2();
Other2 object3 = new Other2();
[code]....
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Mar 17, 2014
how objects relate to classes and how you can create and re-use object types.on that point, but this has me baffled. I most certainly do not have a firm grasp yet on passing things to and from methods that just makes my head hurt. SO anyway I tried out one of the code examples:
/* ElectricGuitar.java */
class ElectricGuitar {
String brand;
int numOfPickups;
boolean rockStarUsesIt;
[code]...
But I just realized this thing has no main method and only one class defined.....so I guess I just tried to compile.
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Mar 21, 2014
How many ways to create an object in java ?
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Sep 18, 2014
I get an json from http request. I want to create a corresponding Java object.
is there any automated mapping? Something called pojo or something else?
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Jul 18, 2014
Why we can't create object of abstract class ,when we can create its constructor?
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Jul 4, 2014
//Scanner Test
String stream2 = "ab34ef
56";
// create a new scanner with the specified String Object
Scanner scanner = new Scanner(stream1);
// find a string "World"
[Code] ....
Matched expression found by findInLine: 34
ef56
is new line? right?
The java.util.Scanner.nextLine() method advances this scanner past the current line and returns the input that was skipped. This method returns the rest of the current line, excluding any line separator at the end.
then 56 is in new line and it must return ef.What is the problem?
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Dec 11, 2012
I know that System is a final class and it cannot be instantiated, out is a static final variable of type PrintStream in System class and println is a method in PrintStream class.Still I don't understand why we use System.out to call println() method.To my knowledge a method can be called using an object reference, in case of static behaviors we use classname. Then why here we are using System.out.println? Can't we just create an object of PrintStream class and call the println() method as PrintStream class can be instantiated.Are there any ways of calling a method apart from those I know(I have mentioned above what I know)?
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Oct 5, 2014
Animal ob1=new Lion();
Here we create ob1 for Animal class or Lion class.
public abstract class Animal {
public abstract void eat();
public void breathe(){
[Code] ....
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Sep 19, 2014
Programming Assignment #2
(Using an Existing Class: Creating Objects and Calling Accessor and Mutator Methods)
I. The Assignment
This assignment is to write a "test" class (aka: a "driver" class or "client code") that uses the class Balloon.java, available on the class web page.
To use the Balloon class, download it and store it in the src folder of your NetBeans project. Make sure you save it as Balloon.java.
The best way to learn how to use the Balloon class or any other Java class, for that matter - is to consult the documentation, Balloon.html (online). You can also read the javadoc comments that appear just above the class declaration and above each method declaration, which explain what each method does, what the method's parameters are, and what value if any - is returned by the method. The html support pages are generated from these comments.
-Review declaring variables, creating objects, calling methods that return a value vs. void methods, and accessor and mutator methods before beginning. To receive credit for this assignment, you must not modify the Balloon class in any way!
II. Your BalloonTester Class
Your BalloonTester class will have only a single method "main" and will perform each of the following operations, in the exact order listed below. Each operation may be done in one or two statements. Make sure you follow directions faithfully, and note that once you have done step 3, you can copy and paste it to do steps 6, 9, and 12.
1.Create a Balloon object with a name of your own choosing and an altitude of 100 meters.
2.Create a second Balloon object with a name of your own choosing, and specify an initial altitude of -100 meters.
3.Call the accessor methods of the Balloon class to get the name and altitude of each Balloon object. Print the data, one object per line.
4.Make the object you created in step 1 ascend to an altitude of 250 meters.
5.Call the adjustAltitude method to increase the altitude of the object you created in step 2 by 150 meters.
6.Call the accessor methods of the Balloon class to get the name and altitude of each object. Print the data, one object per line.
7.Call the adjustAltitude method to decrease the altitude of the object you created in step 1 by 150 meters.
8.Make the object you created in step 2 descend to the same altitude as the other object. You may assume that the other object is at a lower altitude.
To get credit for step 8., the statement(s) you write must always work, regardless of the actual altitude of the second object. It cannot depend on you knowing the altitude of the second object, but must utilize the fact that the object knows its own altitude. In other words, if you use a literal in any way to set the altitude, it is not correct.
9.Call the accessor methods to get the name and altitude of each object. Print the data, one object per line.
10.Move the object you created in step 1 to an altitude that is four times its current altitude. As in step 8, the statement(s) you write must work for any altitude and may not depend on you figuring out the new altitude beforehand.
11.Attempt to move the object you created in step 2 to an altitude that is 150 meters below its current altitude.
12.Call the accessor methods to get the name and altitude of each object. Print the data, one object per line.
and this is the Balloon.java given:
// File: Balloon2.java
// Modified Balloon class has overloaded constructors
/**
* A class to represent a hot-air balloon. Balloon objects have a name and an altitude.
*/
public class Balloon2
{
// instance variables
private String name ; // name of the balloon
private int altitude; // altitude (height) of balloon in meters
[Code] ....
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Apr 16, 2014
I'm curious why ACM isn't letting me create an object from a different class, maybe I am missing something?
my main class:
import java.awt.Color;
import acm.program.*;
import acm.graphics.*;
public class MyClass extends GraphicsProgram {
private static final int WINDOW_W = 500;
private static final int WINDOW_H = 500;
[code]....
I have also noticed when trying to extend 'ConsoleProgram' it does the same thing with line printing (except when using system.out).
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Oct 26, 2014
I can't figure out where to create the StringHandler object. My code should take a string as input, then create StringHandler object ord with the string input. This should repeat until cancel is pressed, then ord should be sent to the Utskrift-method (a print method).
If I do like this, null is also sent to Utskrift. I dont want that to happen.
If I put StringHandler last in the loop ord can not be resolved.
String text = "";
while (text != null){
text = showInputDialog(null, "Enter text:");
StringHandler ord = new StringHandler(text);
if (text == null){
[Utskrift(ord.getNumber(), ord.getString(), ord.getWords());
break;
}
}
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Feb 26, 2015
I've been writing classes over and over for school. So I create a class outside of my main class. I create a new constructor and then create objects from my main class. I hope that makes sense. So i use methods in that class to work with the object. So I have an object name I've created <dot> method name. So I can create objects and then use methods from the class, but I'm wondering can I create a method in my main class and use it on that object? I don't understand how to do that.
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Oct 12, 2014
Write a program that prompts the user for information about some countries, creates an object for each country, and then stores the objects in an array. After the user has entered information about all the countries, your program should print out which countries in the list have the smallest and largest area and population density. Assume the user will enter information about at least one country but that the program will not have to store more than ten countries in the array. The user will indicate that they are done entering countries by typing "DONE" for a country name. Here is an example of what your program must look like when it is executed (user input is shown bold)
Please enter the name of a country: United States
Enter the area in square km and population of United States: 9827000 310000000
Please enter the name of a country: Mexico
Enter the area in square km and population of Mexico: 1973000 122300000
Please enter the name of a country: Canada
Enter the area in square km and population of Canada: 9985000 35160000
Please enter the name of a country: Liberia
Enter the area in square km and population of Liberia: 111370 4294000
Please enter the name of a country: DONE
Liberia has the smallest area at 111370 square km.
Canada has the largest area at 9985000 square km.
Canada has the smallest population density at 3.521282 people per square km.
Mexico has the largest population density at 61.986822 people per square km.
I don't know, I'm really confused with this Java program. I don't know how to do the main part of the program where the user inputs, array, and the output.
// Access the Scanner and ArrayList class by importing the java.util package.
import java.util.Scanner;
/** Project - A Country Object
* The purpose of this program is for the user to enter some information at most 10 countries. After the user has entered information about all the countries, the program should print out which countries in the list have the smallest and largest area and population density.
*/
public class Country
{
private String countryName;
private int theArea;
private int thePopulation;
public Country(String countryName, int thePopulation, int theArea)
[Code] ....
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Nov 20, 2014
I am working on a project using pictures and am having some trouble. My assignment is to take a jpeg, and reflect it(over an imaginary x-axis so to speak). As this is my first time working with images, I am very lost. My approach was to take "pixel 0" and have it swap places with "pixel max". Theoretically, I believe I would only need to do this for the first 50% of the pixels, as each flip works on 2 opposite pixels. With my code thus far (the reflect() method), I print the left half of the image. Note: I must use pixel manipulation. I cannot use graphics.
public class MyArt
{
private Picture image;
/**
* Create an Art object using the jpg or bmp at the indicated location
*/
public MyArt(String filename)
{
image = new Picture(filename);
[Code] .....
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Mar 29, 2014
I am working on eclipse kepler, JSF 2.2 with PrimeFaces 4.0 / Mojarra 2.2 library.
actually there are 2 Problems:
I still get this server message no matter what I do.
(( javax.el.PropertyNotFoundException: /Order.xhtml @28,76 value="#{kk.refugee.id}": Target Unreachable, 'refugee' returned null))
and if I delete the input text puls the hidden, the message keeps pop up for 'material' selectOneMenu. -
I have no chance to examin : ((is this javascript code correct, to copy the value of one component to the other.)) these are my xhtml file and java calsses.
**kk.java**
-----------
package khldqr.beans;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
@SessionScoped
@ManagedBean
public class kk {
[code]....
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Dec 19, 2014
dynamically create tabs by pressing a button, each tab has Primefaces input texts in which i'll be adding stuff and with a Submit button i'm submitting the form.
My issue now is this; although I can create more buttons through my managed bean, I cannot set the ValueExpression to the InputTexts. When I do:
inputName.setValueExpression("value", createValueExpression("#{cdiBean.name}",String.class)); it doesn't work.
The createValueExpression is a static method in my managed bean and it returns a ValueExpression. I'm most certain I found it online, not sure where though, it's been over a month since the last time I worked with this topic.
Anyway, is my whole "methodology" correct? Should I do anything differently?
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Mar 27, 2015
I have a question regarding static binding and dynamic binding. Say for example we have below hierarchy,
class Animal
{
public void eat() {
System.out.println("Animal Eating");
}
}
[Code] .....
1) a.eat(); // Prints Animal eating ---> Static Binding 2) a.eat(); // Prints Dog eating ----> Dynamic Binding
Static Binding means,compiler will be able to decide which method to call based on class type of reference variable at compile time.That is compiler will check whether method is available or not in class.
Dynamic binding means,at runtime JVM will run the method implementaton,based on the object which reference variable is pointing.
So basically compiler will check class type of reference variable and at runtime JVM will check what type of object reference variable is pointing.
Here my my doubt is , in below both cases,that is
1) a.eat(); // Prints Animal eating ---> Static Binding
2) a1.eat(); // Prints Dog eating ----> Dynamic Binding
At compile time,compiler will check whether method is available or not in class. Since eat() method is available ,then in both cases it should be Static binding. or at run time if JVM decides which method implementation to call,then JVM will check which object the reference variable is pointing,then in above 2 cases also JVM will check in Animal object and Dog object for the method eat(). Since eat() method available then both should be dynamic binding.
I am getting doubt on what parameters/conditions we are deciding which is static binding and which is dynamic binding .
Will compiler will check the type of reference variable and also type of object at compile time and when it is ambiguous it leaves the decision to JVM?
Or is it like if method call and method implementation belong to same class then it is static binding and if method call and method implementation belong to different class in same inheritance hierarchy then dynamic binding.
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Jul 8, 2014
I have an editable JTable that has a lot of JComboBox's as cell entries. I would like to be able to "arrow over" to said cell, and with a pressing of either a numerical button or by typing the first letter of the String selection (possibly followed by a second), be able to select the appropriate selection from the cell's JComboBox. I have tried to add a key listener to the JComboBox itself, which works given that I click on said cell and show its menu.
How would I go about ensuring that, when focus is on the cell itself, and I start typing, the appropriate selection is chosen?? (I think this might get into key binding, but I don't know if I have to try it from the scope of JTable, or from that JTable's TableModel (which I have made my custom version of).
Here is what I have so far (everything but SandwichNumber, SandwichName, and Oregano uses JComboBox): [URL] ...., how would I do such key binding?
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Jul 1, 2014
I can't figure out how using binding on selectionModelProperty in a ListView that is using MULTIPLE selection model. I want bind my bean in which I've a list of item A and the selection of that items into the List.
ListView<A> listView; listView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
My bean return a ReadOnlyListProperty<A>
So I don't know how do:
listView.selectionModelProperty().bindBidirectional(bean.getItems());
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