Swing/AWT/SWT :: Pass Object With Properties To Another Object
Jun 11, 2014
I am trying to find either some references to point me on the right track with passing an object with all of it's properties still in tact after it's been created. Currently I am trying to do this through an interface but it seems to just create a new object everytime without the properties. Example below :
import java.util.ArrayList;
import java.util.List;
public interface TPerson{
//public Person p = null;
}
class Thrower {
Person p;
[code]....
When I implement the interface on the other objects as soon as I call the setP method shown above it seems to just create a new one even though I pass the object to the method I want to use.
I’m teaching myself Java. I am a fairly proficient programmer in other languages, but this is the first OO language I’m doing.I have a question that is a bit hard to summarize. Or it should be: how can I pass on an object (or variable) to an event listener?
I am writing an application in which you can play a Sudoku game. I have separated the “logic” or the “model”(the classes with Sudoku data structures and methods to manipulate them) from the presentation (the view and the controller).The main method starts off as follows:
SudokuModel model = new SudokuModel(); SudokuView viewController = new SudokuViewController(model);
The first line creates class for the logic and the second line creates the class for the view and the controller. Since the view and the controller need access to the business logic, the model is passed on to the ViewController class.The SudokuViewController class creates the user interface in Swing and it handles the user input. For the user input I have created a number of listeners, like this:
table.addKeyListener(this);
Now these listeners need access to the model since they update it. However, as far as I’m aware the only parameter passed on to an event listener is the event itself. So these event listeners do not have direct access to the model, even though it is passed on to the constructor of the class SudokuViewController.
To circumvent this, I made model2 an attribute (variable) of the class SudokuViewController. The constructor of the class sets this variable as follows:
model2 = model;
Now the event listeners have access to model2, which they can manipulate.This works. However, I think it is an ugly solution, introducing an additional object (model2). I’d like to pass on the object named model to the event listener, but this doesn’t seem to be possible.
I have created Person.java with the following attributes:
private String firstName; private String lastName; private int age;
My main method parses the XML, loops through each person, and gets the attributes for each.
I need to create instances of my Person class. I could write something like this:
Person person = new Person(); for (int i = 0; i < attributes.getLength; i++) { if (attribute.getName(i) = "firstname") { person.firstName = attribute.getValue(i);} if (attribute.getName(i) = "lastname") { person.lastName = attribute.getValue(i); } if (attribute.getName(i) = "age") { person.age = attribute.getValue(i); } }
Since my actual XML has quite a few attributes, I would rather do something like this:
Person person = new Person(); for (int i = 0; i < attributes.getLength(); i++) { person[attribute.getName(i)] = attribute.getValue(i); }
I am having trouble with a mouse click method. In short I have a hexagon grid, and every time I want to click on one particular hexagon I want the color of the hexagon to change to blue(by default the color is grey). This part works, but when I go to click on another hexagon I want the color of the previous hexagon to change back to grey while at the same time changing the color of the current hexagon clicked to blue. So in other words, I only want one hexagon blue at a time. How might I do this?
I have a hexagon class for one particular hexagon, and a hexmap class for multiple hexagons. I know I should probably be handling mouse clicks in the hexmap since it deals with the whole thing. But I cannot say something like hexagon.setColor within a mouselistener in that class(it gives me a lot of issues). Here is some of my code :
public class Hexagons() public Hexagons(HexMap theMap, int mapRow, int mapCol, int width, int height) { this.map = theMap; this.row = mapRow; this.col = mapCol; this.width = width; this.height = height;
What I want to do is have a label that is updated whenever an object gets some new, relevant data.The way you do it in Java looks different from the way we do it in Objective-C. In Objective-C, we have what's known as a protocol. An Objective-C protocol is almost exactly like a Java "implementation." In Obj-C, if I want the user to see the address of where he is, I can have an object that gets the information and invokes a view controller's method; at that point, the view controller would then take the data passed to it and display the data in a label. However, the view controller is an instance of a subclass of the bundled view controller class.
When I hit the url at the first time my call goes to the spring controller and sets the userDetails objects in the modelAndView.addObject("userDetails", userDetails.getUserDetails()) and returns the userDetails.html page. if I click any link in the same page i want to pass same (userDetails) object thru javascript or jquery and calls the another(controller) method and returns the same (userDetails.html) page.
It means how can I pass the java object thru javascript or jquery and calls the controller. If I get the same object in my controller i can avoid calling the db again.
public void randomCreate(ParentObject obj){ int x = random(0-4); //pseudo int y = random(0-4); //pseudo create new ParentObj(x,y); }
ParentObject is actually abstract, so you would only ever pass one of its children objects to it, and a child object of that type would be created. It seems like there should be a way to pass a type, rather than an object, and then create an instance later down, but I don't know if that is actually possible, or if it is poor programming style.
Create an equals method that takes an object reference and returns true if the given object equals this object.
Hint: You'll need 'instanceof' and cast to a (Geocache)
So far I have:
public boolean equals(Object O){ if(O instanceof Geocache){ Geocache j=(Geocache) O; if (this.equals(j)) //I know this is wrong... but I can't figure it out return true; }
else return false; }
I think I have it correct up to the casting but I don't understand what I'm suppose to do with the this.equals(). Also I'm getting an error that I'm not returning a boolean... I get this all the time in other problems. I don't get why since I have to instances of returning booleans in this. "returns true if the given object equals this object" makes no sense to me. I assume the given object, in my case, is 'O'. What is 'this' object referring to?
I am new to Java and have read books, the Java docs, and searched the Internet for my problem to no avail. I have an Array of objects that contains strings. How can I get the object's strings to print in a list so that the user can select that object to manipulate its attributes? For example, the user can select "Guitar 1" from a list and manipulate its attributes like tuning it, playing it, etc. I have a class called Instruments and created 10 guitar objects.Here is the code:
Instrument [] guitar = new Instrument[10]; for (int i = 0; i < 10; i++) { guitar[0] = new Instrument("Guitar 1"); guitar[1] = new Instrument("Guitar 2"); guitar[2] = new Instrument("Guitar 3"); guitar[3] = new Instrument("Guitar 4"); guitar[4] = new Instrument("Guitar 5"); guitar[5] = new Instrument("Guitar 6");
Now lets say that I want to access a method 'addInterest()' that is in the 'SavingsAccount' class I would have to do: '((SavingsAccount)s).addInterest();'
The question I have is why do I have to cast 'b' to SavingsAccount? Isn't the actual object reference of 'b' already an instance of 'SavingsAccount' class? How does the 'BankAccount' affect the object itself? I'm really confused as to what class is truly getting instantiated and how BankAccount and SavingsAccount are both functioning to make the object 'b'.
I don't understand why the object reference variable 'a' cannot be recast from a thisA object reference to a thisB object reference.Is it the case that once a reference variable is linked to a particular object type then it cannot switch object types later on.I am facing the Java Associate Developer exam soon and I am just clearing up some issues in my head around object reference variable assignment,
class thisA {} class thisB extends thisA { String testString = "test";} public class CastQuestion2 { public static void main(String[] args) { thisA a = new thisA(); thisB b = new thisB();
I am trying to get this to where I can type in a name and it will search through each object and print back the corresponding object info.
Java Code:
import java.util.Scanner; public class MyPeople { public static void main(String[] args) { Person[] p = new Person[] { new Person("Chris", 26, "Male", "NJ", "Single"), new Person("JoAnna", 23, "Female", "NJ", "Single"), new Person("Dana", 24, "Female", "NJ", "Single"), new Person("Dan", 25, "Male", "NJ", "Single"), new Person("Mike", 31, "Male", "NJ", "Married") };
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); } }
I have just started working with linked lists. I have a linked list of Objects and I want to be able to search for a specific object. But currently my code continues to return false. Also how would I go about removing the first index of the linked list.
public static void main(String[] args) { LinkedList<Cookies> ml = new LinkedList<>(); int choice = 0; while (choice >= 0) { choice = menu();
I am reading Head First: Java and got to Object References. In the book I got a little bit confused on what happens when two object reference's point at the same object so I wrote a small crude test, the below code. This of course clarified what happens but what I am interested in knowing is in what circumstances would you want to have two separate references for the same object when you could just use the original? Eg. v1
class ObjectValue{ int objVal = 1; } class ObjectValueTestDrive{ public static void main(String [] args){ // "Value of v# should be" refers to if it copied the given object values, instead of referencing the same object ObjectValue v1 = new ObjectValue(); System.out.println("Value of v1 should be 1:" + " "+ v1.objVal);
Explain anonymous objects with example clearly...i read some where anonymous objects advantage is saving memory...it is benificiable when there is only one time object usage in our program..i can't understand one time usage of object ....i know anonymous objects but i don't know in which context we use them in our programs...i did the anonymous object program with my own example but i can't differentiate this one with normal object..i'm providing my own example below
//anonymous object public class anonymous { int x=10; int y=25; void display() { System.out.println("anomymous");
I've been trying to learn Java for the last 36 hours or so (after applying for a HTML/CSS job saying "Java knowledge preferred"), and decided to experiment a bit making a graphical tic-tac-toe game. I eventually managed to get that done and it's working. Working code below:
[Java] tic tac toe 1 - Pastebin
So, it works to an extent, however, the way I am capturing which cell is selected seems very sloppy, and would not work if the cells weren't squares or rectangles. So I made a copy of the project and restructured it adding the mouse event to the cells, but now I can't get JComponent to repaint. New code below:
tic tac toe 2 - Pastebin
Curiously, clicking triggers the action for all 9 cells, but I presume it's because I haven't bounded them making it think I've clicked all 9 simultaneously.
What I've tried:
Make the Cell class extend the game class and call this.repaint()- causes stack overflow.
Calling Game.GameState() within the cell clicking event and making that function static - compiler doesn't like calling repaint() inside a static function.
Making another class to make a clone of the Game object and then refresh- was never going to work....
java.awt.Component is an abstract class, and it's direct Sub-classes are Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar, Text Component
So, when I use addXListener(mylistenerclass m);//which is a method of Component class which object is holding the list of all listeners, for a particular Event Source?
I am under the assumption that - there is an Event Source Object(possibly static) for every Event Source type(mouse, keyboard etc) that holds a list of destinations(classes that implements their listener interface) - added to the the object via addXListener method. When an event happens(mouse click, drag etc) the Event Source Object creates an Event Object and send it to all the destinations. Is my assumption correct? I can't seem to find the location or declaration of Event Source Object and the list where it stores it's registered destinations.
I'm not even sure if that is the right question to ask. I've been confused by what is A Graphics object for a while now, I used to think that it is simply a tool to use to change colors and draw to specific container(ie JFrame, JPanel). However, I've been studying buffering(triple, double, flipping...etc) and how it works for 3 days now, and my confusion has only increased. for instance, why when we need to draw to the buffer(ie BufferStrategy, BufferedImage) we get its own graphics object to draw to it and then we project it to the screen?
Does the Graphics Object represent the drawing surface (ie the JPanel it self if we're using one to draw custom painting via JPanel#paintComponent(Graphics g)) ? and so when we're getting the graphics object of a buffer, do we actually get its drawing surface to paint on?
So generally speaking if we are using a JPanel and we say bufferedImage#createGraphics and use that graphics object to draw to, we would not be drawing to the JPanel but to the BufferedImage correct?
I have two JFrames the first one is a log in screen where i log in to the log in server that i made using RMI . If the log in succeeds i send the user object witch is Serializable to the second JFrame.
The user object is received from the server. This object contains all the information needed in the second JFrame. This second JFrame is made inside the first one and i defined a method with witch i send this user object to the second frame.
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.
