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  • Should DAL always return business objects in MVP

    - by Chathuranga
    In Model View Presenter (MVP) pattern, it is said that our DAL always should returns business models. But let's say if I want to get just a number from database like the last ClientID (the latest clients ID) which is a string, should my DAL method returns a ClientInfo object which has about 10 other fields as well like ClientName, Address etc.? If I want to get a list of business objects from my DAL, is it acceptable to do it as follows or better to get a DataTable from DAL and then in the applications BLL, converts it a List? public List<Employee> GetNewEmployees() { string selectStatement = "SELECT Employee.Emp_ID, Employee.Initials + ' ' + Employee.Surname AS Name,..."; using (SqlConnection sqlConnection = new SqlConnection(db.GetConnectionString)) { using (SqlCommand sqlCommand = new SqlCommand(selectStatement, sqlConnection)) { sqlConnection.Open(); using (SqlDataReader dataReader = sqlCommand.ExecuteReader()) { List<Employee> list = new List<Employee>(); while (dataReader.Read()) { list.Add ( new EpfEtfMaster { EmployeeID = (int) dataReader ["emp_id"], EmployeeName = (string) dataReader ["Name"], AppointmentDate = (DateTime) dataReader["appointment_date"], }); } return list; } } } }

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  • HMVC/PAC - how to handle shared abstractions/models?

    - by fig-gnuton
    In HMVC/PAC, what's the recommended way to code if two or more triads/agents share a common model/abstraction? Do you instantiate a new instance of that model wherever needed, and propogate a change in one to all the other instances via the controllers? Or do instantiate one model at some common upper level, and inject that instance wherever needed? (Or neither if I'm missing something fundamental about these patterns?)

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  • Thread not behaving correctly

    - by ivor
    Hello, I wonder if anyone can help me to understand where I could be going wrong with this code; Basically I'm working on a turorial and calling the class below from another class - and it is getting the following error; Exception in thread "Thread-1" java.lang.NullPointerException at org.newdawn.spaceinvaders.TCPChat.run(TCPChat.java:322) at java.lang.Thread.run(Unknown Source) I realise the error is beibg flagged in another class- but I have tested the other class with a small class which sets up a separate thread - and it works fine, but as soon as I try and implement a new thread in this class - it causes all sorts of problems. Am I setting up the thread correctly in this class? Basically I can set up a thread in this class, with a test loop and it's fine, but when I bring in the functionality of the rest of the game it sometimes hangs, or does not display at all. Any suggestions on where I could be going wrong would be greatly appreciated. Thanks for looking. package org.newdawn.spaceinvaders; import java.awt.BorderLayout; import java.awt.Canvas; import java.awt.Color; import java.awt.Dimension; import java.awt.FlowLayout; import java.awt.Graphics2D; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.awt.image.BufferStrategy; import java.util.ArrayList; import java.util.Scanner; import java.awt.*;//maybe not needed import javax.swing.*;//maybenot needed import java.util.Random; //import java.io.*; /** * The main hook of our game. This class with both act as a manager * for the display and central mediator for the game logic. * * Display management will consist of a loop that cycles round all * entities in the game asking them to move and then drawing them * in the appropriate place. With the help of an inner class it * will also allow the player to control the main ship. * * As a mediator it will be informed when entities within our game * detect events (e.g. alient killed, played died) and will take * appropriate game actions. * * @author Kevin Glass */ public class Game extends Canvas implements Runnable{ /** The stragey that allows us to use accelerate page flipping */ private BufferStrategy strategy; /** True if the game is currently "running", i.e. the game loop is looping */ private boolean gameRunning = true; /** The list of all the entities that exist in our game */ private ArrayList entities = new ArrayList(); /** The list of entities that need to be removed from the game this loop */ private ArrayList removeList = new ArrayList(); /** The entity representing the player */ private Entity ship; /** The speed at which the player's ship should move (pixels/sec) */ private double moveSpeed = 300; /** The time at which last fired a shot */ private long lastFire = 0; /** The interval between our players shot (ms) */ private long firingInterval = 500; /** The number of aliens left on the screen */ private int alienCount; /** The number of levels progressed */ private double levelCount; /** high score for the user */ private int highScore; /** high score for the user */ private String player = "bob"; //private GetUserInput getPlayer; /** The list of entities that need to be removed from the game this loop */ /** The message to display which waiting for a key press */ private String message = ""; /** True if we're holding up game play until a key has been pressed */ private boolean waitingForKeyPress = true; /** True if the left cursor key is currently pressed */ private boolean leftPressed = false; /** True if the right cursor key is currently pressed */ private boolean rightPressed = false; /** True if we are firing */ private boolean firePressed = false; /** True if game logic needs to be applied this loop, normally as a result of a game event */ private boolean logicRequiredThisLoop = false; //private Thread cThread = new Thread(this); //public Thread t = new Thread(this); //private Thread g = new Thread(this); void setHighscore(int setHS) { highScore = setHS; } public int getHighscore() { return highScore; } public void setPlayer(String setPlayer) { player = setPlayer; } public String getPlayer() { return player; } public void run() { //setup(); System.out.println("hello im running bob"); /*int count = 1; do { System.out.println("Count is: " + count); count++; try{Thread.sleep(1);} catch(InterruptedException e){} } while (count <= 2000000);*/ //Game g =new Game(); //Game g = this; // Start the main game loop, note: this method will not // return until the game has finished running. Hence we are // using the actual main thread to run the game. //setup(); //this.gameLoop(); //try{thread.sleep(1);} //catch{InterruptedException e} } /** * Construct our game and set it running. */ public Game () { //Thread t = new Thread(this);//set up new thread for invaders game //t.run();//run the run method of the game //Game g =new Game(); //setup(); //Thread t = new Thread(this); //thread.start(); //SwingUtilities.invokeLater(this); Thread er = new Thread(this); er.start(); } public void setup(){ //initialise highscore setHighscore(0); // create a frame to contain our game JFrame container = new JFrame("Space Invaders 101"); // get hold the content of the frame and set up the resolution of the game JPanel panel = (JPanel) container.getContentPane(); panel.setPreferredSize(new Dimension(800,600)); //panel.setLayout(null); // setup our canvas size and put it into the content of the frame setBounds(0,0,800,600); panel.add(this); // Tell AWT not to bother repainting our canvas since we're // going to do that our self in accelerated mode setIgnoreRepaint(true); // finally make the window visible container.pack(); container.setResizable(false); container.setVisible(true); // add a listener to respond to the user closing the window. If they // do we'd like to exit the game container.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { //cThread.interrupt(); System.exit(0); } }); // add a key input system (defined below) to our canvas // so we can respond to key pressed addKeyListener(new KeyInputHandler()); // request the focus so key events come to us requestFocus(); // create the buffering strategy which will allow AWT // to manage our accelerated graphics createBufferStrategy(2); strategy = getBufferStrategy(); // initialise the entities in our game so there's something // to see at startup initEntities(); } /** * Start a fresh game, this should clear out any old data and * create a new set. */ private void startGame() { // clear out any existing entities and intialise a new set entities.clear(); initEntities(); //initialise highscore setHighscore(0); // blank out any keyboard settings we might currently have leftPressed = false; rightPressed = false; firePressed = false; } /** * Initialise the starting state of the entities (ship and aliens). Each * entitiy will be added to the overall list of entities in the game. */ //private void initEntities() { public void initEntities() { Random randomAlien = new Random(); // create the player ship and place it roughly in the center of the screen //ship = new ShipEntity(this,"sprites/ship.gif",370,550);//orignal ship = new ShipEntity(this,"sprites/ship.gif",700,300);//changed postioning to right hand side entities.add(ship); // create a block of aliens (5 rows, by 12 aliens, spaced evenly) alienCount = 0; levelCount = 1.02; for (int row=0;row<7;row++) {//altered number of rows for (int x=0;x<5;x++) { int r = randomAlien.nextInt(100);//loop added to produce random aliens if (r < 50){ //Entity alien = new AlienEntity(this,"sprites/alien.gif",/*100+*/(x*50),(50)+row*30); Entity alien = new AlienEntity(this,"sprites/alien.gif",100+(x*90),(12)+row*85); entities.add(alien); alienCount++; } } } } //private void initEntities() { public void initAlienEntities() { Random randomAlien = new Random(); // create the player ship and place it roughly in the center of the screen //ship = new ShipEntity(this,"sprites/ship.gif",370,550);//orignal //ship = new ShipEntity(this,"sprites/ship.gif",700,300);//changed postioning to right hand side //entities.add(ship); // create a block of aliens (5 rows, by 12 aliens, spaced evenly) alienCount = 0; levelCount = levelCount + 0.10;//this increases the speed on every level for (int row=0;row<7;row++) {//altered number of rows for (int x=0;x<5;x++) { int r = randomAlien.nextInt(100);//loop added to produce random aliens if (r < 50){//randome check to show alien //Entity alien = new AlienEntity(this,"sprites/alien.gif",/*100+*/(x*50),(50)+row*30); Entity alien = new AlienEntity(this,"sprites/alien.gif",-250+(x*90),(12)+row*85); entities.add(alien); alienCount++; } } } advanceAlienSpeed(levelCount); } /** * Notification from a game entity that the logic of the game * should be run at the next opportunity (normally as a result of some * game event) */ public void updateLogic() { logicRequiredThisLoop = true; } /** * Remove an entity from the game. The entity removed will * no longer move or be drawn. * * @param entity The entity that should be removed */ public void removeEntity(Entity entity) { removeList.add(entity); } /** * Notification that the player has died. */ public void notifyDeath() { message = "Oh no! They got you, try again?"; waitingForKeyPress = true; } /** * Notification that the player has won since all the aliens * are dead. */ public void notifyWin() { message = "Well done! You Win!"; waitingForKeyPress = true; } /** * Notification that an alien has been killed */ public void notifyAlienKilled() { // reduce the alient count, if there are none left, the player has won! alienCount--; if (alienCount == 0) { //notifyWin();win not relevant here... this.initAlienEntities();//call fresh batch of aliens } // if there are still some aliens left then they all need to get faster, so // speed up all the existing aliens advanceAlienSpeed(1.30); } public void advanceAlienSpeed(double speed) { // if there are still some aliens left then they all need to get faster, so // speed up all the existing aliens for (int i=0;i<entities.size();i++) { Entity entity = (Entity) entities.get(i); if (entity instanceof AlienEntity) { // speed up by 2% entity.setHorizontalMovement(entity.getHorizontalMovement() * speed); //entity.setVerticalMovement(entity.getVerticalMovement() * 1.02); } } } /** * Attempt to fire a shot from the player. Its called "try" * since we must first check that the player can fire at this * point, i.e. has he/she waited long enough between shots */ public void tryToFire() { // check that we have waiting long enough to fire if (System.currentTimeMillis() - lastFire < firingInterval) { return; } // if we waited long enough, create the shot entity, and record the time. lastFire = System.currentTimeMillis(); ShotEntity shot = new ShotEntity(this,"sprites/shot.gif",ship.getX()+10,ship.getY()-30); entities.add(shot); } /** * The main game loop. This loop is running during all game * play as is responsible for the following activities: * <p> * - Working out the speed of the game loop to update moves * - Moving the game entities * - Drawing the screen contents (entities, text) * - Updating game events * - Checking Input * <p> */ public void gameLoop() { long lastLoopTime = System.currentTimeMillis(); // keep looping round til the game ends while (gameRunning) { // work out how long its been since the last update, this // will be used to calculate how far the entities should // move this loop long delta = System.currentTimeMillis() - lastLoopTime; lastLoopTime = System.currentTimeMillis(); // Get hold of a graphics context for the accelerated // surface and blank it out Graphics2D g = (Graphics2D) strategy.getDrawGraphics(); g.setColor(Color.black); g.fillRect(0,0,800,600); // cycle round asking each entity to move itself if (!waitingForKeyPress) { for (int i=0;i<entities.size();i++) { Entity entity = (Entity) entities.get(i); entity.move(delta); } } // cycle round drawing all the entities we have in the game for (int i=0;i<entities.size();i++) { Entity entity = (Entity) entities.get(i); entity.draw(g); } // brute force collisions, compare every entity against // every other entity. If any of them collide notify // both entities that the collision has occured for (int p=0;p<entities.size();p++) { for (int s=p+1;s<entities.size();s++) { Entity me = (Entity) entities.get(p); Entity him = (Entity) entities.get(s); if (me.collidesWith(him)) { me.collidedWith(him); him.collidedWith(me); } } } // remove any entity that has been marked for clear up entities.removeAll(removeList); removeList.clear(); // if a game event has indicated that game logic should // be resolved, cycle round every entity requesting that // their personal logic should be considered. if (logicRequiredThisLoop) { //g.drawString("Press any key",(800-g.getFontMetrics().stringWidth("Press any key"))/2,300); for (int i=0;i<entities.size();i++) { Entity entity = (Entity) entities.get(i); entity.doLogic(); } logicRequiredThisLoop = false; } // if we're waiting for an "any key" press then draw the // current message //show highscore at top of screen //show name at top of screen g.setColor(Color.white); g.drawString("Player : "+getPlayer()+" : Score : "+getHighscore(),20,20); if (waitingForKeyPress) { g.setColor(Color.white); g.drawString(message,(800-g.getFontMetrics().stringWidth(message))/2,250); g.drawString("Press any key",(800-g.getFontMetrics().stringWidth("Press any key"))/2,300); } // finally, we've completed drawing so clear up the graphics // and flip the buffer over g.dispose(); strategy.show(); // resolve the movement of the ship. First assume the ship // isn't moving. If either cursor key is pressed then // update the movement appropraitely ship.setVerticalMovement(0);//set to vertical movement if ((leftPressed) && (!rightPressed)) { ship.setVerticalMovement(-moveSpeed);//**took out setHorizaontalMOvement } else if ((rightPressed) && (!leftPressed)) { ship.setVerticalMovement(moveSpeed);//**took out setHorizaontalMOvement } // if we're pressing fire, attempt to fire if (firePressed) { tryToFire(); } // finally pause for a bit. Note: this should run us at about // 100 fps but on windows this might vary each loop due to // a bad implementation of timer try { Thread.sleep(10); } catch (Exception e) {} } } /** * A class to handle keyboard input from the user. The class * handles both dynamic input during game play, i.e. left/right * and shoot, and more static type input (i.e. press any key to * continue) * * This has been implemented as an inner class more through * habbit then anything else. Its perfectly normal to implement * this as seperate class if slight less convienient. * * @author Kevin Glass */ private class KeyInputHandler extends KeyAdapter { /** The number of key presses we've had while waiting for an "any key" press */ private int pressCount = 1; /** * Notification from AWT that a key has been pressed. Note that * a key being pressed is equal to being pushed down but *NOT* * released. Thats where keyTyped() comes in. * * @param e The details of the key that was pressed */ public void keyPressed(KeyEvent e) { // if we're waiting for an "any key" typed then we don't // want to do anything with just a "press" if (waitingForKeyPress) { return; } // if (e.getKeyCode() == KeyEvent.VK_LEFT) { ////leftPressed = true; ///} //// if (e.getKeyCode() == KeyEvent.VK_RIGHT) { //rightPressed = true; if (e.getKeyCode() == KeyEvent.VK_UP) { leftPressed = true; } if (e.getKeyCode() == KeyEvent.VK_DOWN) { rightPressed = true; } if (e.getKeyCode() == KeyEvent.VK_SPACE) { firePressed = true; } } /** * Notification from AWT that a key has been released. * * @param e The details of the key that was released */ public void keyReleased(KeyEvent e) { // if we're waiting for an "any key" typed then we don't // want to do anything with just a "released" if (waitingForKeyPress) { return; } if (e.getKeyCode() == KeyEvent.VK_UP) {//changed from VK_LEFT leftPressed = false; } if (e.getKeyCode() == KeyEvent.VK_DOWN) {//changed from VK_RIGHT rightPressed = false; } if (e.getKeyCode() == KeyEvent.VK_SPACE) { firePressed = false; } } /** * Notification from AWT that a key has been typed. Note that * typing a key means to both press and then release it. * * @param e The details of the key that was typed. */ public void keyTyped(KeyEvent e) { // if we're waiting for a "any key" type then // check if we've recieved any recently. We may // have had a keyType() event from the user releasing // the shoot or move keys, hence the use of the "pressCount" // counter. if (waitingForKeyPress) { if (pressCount == 1) { // since we've now recieved our key typed // event we can mark it as such and start // our new game waitingForKeyPress = false; startGame(); pressCount = 0; } else { pressCount++; } } // if we hit escape, then quit the game if (e.getKeyChar() == 27) { //cThread.interrupt(); System.exit(0); } } } /** * The entry point into the game. We'll simply create an * instance of class which will start the display and game * loop. * * @param argv The arguments that are passed into our game */ //public static void main(String argv[]) { //Game g =new Game(); // Start the main game loop, note: this method will not // return until the game has finished running. Hence we are // using the actual main thread to run the game. //g.gameLoop(); //} }

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  • Generics and Constrained Polymorphism versus Subtyping

    - by Rahul G
    Hullo all. In this (Warning: PDF) presentation on Haskell Type Classes, on slide #54, there's this question: Open Question: In a language with generics and constrained polymorphism, do you need subtyping too? My questions are: How do generics and constrained polymorphism make subtyping unnecessary? If generics and constrained polymorphism make subtyping unnecessary, why does Scala have subtyping?

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  • How to write Composition and Aggregation in java

    - by Mifas
    I want to know how to identify composition and aggregation code in java. I have C++ Code, But I don't understand how to write in java. Composition class A {}; class B { A composited_A; }; Aggregation via Pointer class A {}; class B { A* pointer_to_A; B(A anA){ pointer_to_A = &anA; } Can anyone please tell me how both are working in JAVA. (I know what is meant by Composition and aggregation ) };

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  • use of assertions for type checking in php?

    - by user151841
    I do some checking of arguments in my classes in php using exception-throwing functions. I have functions that do a basic check ( ===, in_array etc ) and throw an exception on false. So I can do assertNumeric($argument, "\$argument is not numeric."); instead of if ( ! is_numeric($argument) ) { throw new Exception("\$argument is not numeric."); } Saves some typing I was reading in the comments of the php manual page on assert() that As noted on Wikipedia - "assertions are primarily a development tool, they are often disabled when a program is released to the public." and "Assertions should be used to document logically impossible situations and discover programming errors— if the 'impossible' occurs, then something fundamental is clearly wrong. This is distinct from error handling: most error conditions are possible, although some may be extremely unlikely to occur in practice. Using assertions as a general-purpose error handling mechanism is usually unwise: assertions do not allow for graceful recovery from errors, and an assertion failure will often halt the program's execution abruptly. Assertions also do not display a user-friendly error message." This means that the advice given by "gk at proliberty dot com" to force assertions to be enabled, even when they have been disabled manually, goes against best practices of only using them as a development tool So, am I 'doing it wrong'? What other/better ways of doing this are there?

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  • CakePHP form $options['options']

    - by James
    Hey! Total CakePHP noob here. This is sort of a two fold question. In a view that is used for adding user objects I would like to use a drop down (selection) field in the form. Each user belongs to a group so when I add a user I want a drop down that contains all of the groups that the user could possibly join. Currently the group_id field is a textfield. I know how to force it to be a selection field, but I don't know how to populate the selection with the names of the groups programmatically. The Current method: echo $form->input('group_id', array( '1' => 'NameOfGroup1', '2' => 'NameOfGroup2', '3' => 'NameOfGroup3') ); I want to generate the options array programmatically though. echo $form->input('group_id', $this->Group->find('list')); This doesn't work though. I get an error: Undefined property: View::$Group [APP/views/users/add.ctp, line 8] To me this means that I don't have access to the Group object from inside my user view. How can I accomplish this? Again, I want to do it programmatically so that it updates as I add groups or remove them.

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  • How to handle the pylint message: Warning: Method could be a function

    - by biffabacon
    Being new to Python, I decided to get some feedback on a class I'd written ASAP so I ran it against pylint. Is the message it gave "Warning: Method could be a function" telling me that it would be better to move this method out of the class because it doesn't use any instance variables? In c# I would make this a static method. What's the most pythonic thing to do here?

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  • Can a function return an object? Objective-C and NSMutableArray

    - by seaworthy
    I have an NSMutableArray. It's members eventually become members of an array instance in a class. I want to put the instantiantion of NSMutable into a function and to return an array object. If I can do this, I can make some of my code easier to read. Is this possible? Here is what I am trying to figure out. //Definition: > function Objects (float a, float b) { > NSMutableArray *array = [[NSMutableArray alloc] init]; > [array addObject:[NSNumber numberWithFloat:a]]; > [array addObject:[NSNumber numberWithFloat:b]]; > //[release array]; ???????? return array; > } //Declaration: Math *operator = [[Math alloc] init]; [operator findSum:Objects(20.0,30.0)]; My code compiles if I instantiate NSMutableArray right before I send the message to the receiver. I know I can have an array argument along with the method. What I have problem seeing is how to use a function and to replace the argument with a function call. Any help is appreciated. I am interested in the concept not in suggestions to replace the findSum method.

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  • What to name this class?

    - by orlandu63
    (This is not an interface: I simply omitted the method bodies) class _ { protected $_data = array(); function __construct($data); function set($name, $value); function get($name); function __set($name, $value); function __get($name); //aliases for their respective non-magic methods. # and some other generic methods } Essentially it's a class that provides a magical object-oriented reusable access layer to some data. I've considered DataLayer, DataObject and some others; I'd like to hear some suggestions from someone who's more terminologically savvy.

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  • PHP: Recursive array function

    - by Industrial
    Hi everybody, I want to create a function that returns the full path from a set node, back to the root value. I tried to make a recursive function, but ran out of luck totally. What would be an appropriate way to do this? I assume that a recursive function is the only way? Here's the array: Array ( [0] => Array ( [id] => 1 [name] => Root category [_parent] => ) [1] => Array ( [id] => 2 [name] => Category 2 [_parent] => 1 ) [2] => Array ( [id] => 3 [name] => Category 3 [_parent] => 1 ) [3] => Array ( [id] => 4 [name] => Category 4 [_parent] => 3 ) ) The result I want my function to output when getting full path of node id#4: Array ( [0] => Array ( [id] => 1 [name] => Root category [_parent] => ) [1] => Array ( [id] => 3 [name] => Category 3 [_parent] => 1 ) [2] => Array ( [id] => 4 [name] => Category 4 [_parent] => 3 ) ) The notoriously bad example of my recursive skills: function recursive ($id, $array) { $innerarray = array(); foreach ($array as $k => $v) { if ($v['id'] === $id) { if ($v['_parent'] !== '') { $innerarray[] = $v; recursive($v['id'], $array); } } } return $innerarray; } Thanks!

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  • How to add event listners / signals to a simple superman class?

    - by Kabumbus
    I can and would love to use boost or std for this. Sorry - I am new to C++. So I created a really simple program like: #include <iostream> #include <string> using namespace std; class superman { public: string punch(){return cout << "superman: I hit the bad guy!" << endl;}; }; int main() { superman clark; clark.punch(); cin.get(); } I want to add an event listner that would tell me when clark punched and cout something like "superman punched!". How to add such event listner and event function to my class?

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  • objective C architecture question

    - by thekevinscott
    Hey folks, I'm currently teaching myself objective C. I've gone through the tutorials, but I find I learn best when slogging through a project of my own, so I've embarked on making a backgammon app. Now that I'm partway in, I'm realizing there's some overall architecture things I just don't understand. I've established a "player" class, a "piece" class, and a "board" class. A piece theoretically belongs to both a player and the board. For instance, a player has a color, and every turn makes a move; so the player owns his pieces. At the same time, when moving a piece, it has to check whether it's a valid move, whether there are pieces on the board, etc. From my reading it seems like it's frowned upon to reach across classes. For instance, when a player makes a move, where should the function live that moves the piece? Should it exist on board? This would be my instinct, as the board should decide whether a move is valid or not; but the piece needs to initialize that query, as its the one being moved, no? Any info to help a noob would be super appreciated. Thanks guys!

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  • Python: Can subclasses overload inherited methods?

    - by Rosarch
    I'm making a shopping cart app in Google App Engine. I have many classes that derive from a base handler: class BaseHandler(webapp.RequestHandler): def get(self, CSIN=None): self.body(CSIN) Does this mean that the body() method of every descendant class needs to have the same argument? This is cumbersome. Only one descendant actually uses that argument. And what about when I add new args? Do I need to go through and change every class? class Detail(BaseHandler): def body(self, CSIN): class MainPage(BaseHandler): def body(self, CSIN=None): #@UnusedVariable class Cart(BaseHandler): def body(self, CSIN): #@UnusedVariable

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  • Passing pointer position to an object in Java.

    - by Gabriel A. Zorrilla
    I've got a JPanel class called Board with a static subclass, MouseHanlder, which tracks the mouse position along the appropriate listener in Board. My Board class has fields pointerX and pointerY. How do i pass the e.getX() and e.getY() from the MouseHandler subclass to its super class JPanel? I tried with getters, setters, super, and cant get the data transfer between subclass and parent class. I'm certain it's a concept issue, but im stuck. Thanks!

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  • Regular Expressions: RegEx for determining valid PHP class property names?

    - by Brian Lacy
    I am using PHP's magic __set and __get methods to access a private array in a class. I want to make sure the property names requested (i.e. $myObj->FakeProperty) are valid according to PHP property name rules before accessing them. My current RegEx isn't doing the trick; with my test values, _12 always falls through the cracks. I'm not actually sure that my test values even represent a realistic representation of what is and isn't allowed for PHP class property names, but I'm not really too concerned about it, just that I have some sort of rudimentary check in place. Test Fields: albert12 12Albert _12 _Albert12 _12Albert _____a_1 RegEx: ^(?=_*[A-z]+)[A-z0-9_]+$

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  • Is this a good way to expose generic base class methods through an interface?

    - by Nate Heinrich
    I am trying to provide an interface to an abstract generic base class. I want to have a method exposed on the interface that consumes the generic type, but whose implementation is ultimately handled by the classes that inherit from my abstract generic base. However I don't want the subclasses to have to downcast to work with the generic type (as they already know what the type should be). Here is a simple version of the only way I can see to get it to work at the moment. public interface IFoo { void Process(Bar_base bar); } public abstract class FooBase<T> : IFoo where T : Bar_base { abstract void Process(T bar); // Explicit IFoo Implementation void IFoo.Process(Bar_base bar) { if (bar == null) throw new ArgumentNullException(); // Downcast here in base class (less for subclasses to worry about) T downcasted_bar = bar as T; if (downcasted_bar == null) { throw new InvalidOperationException( string.Format("Expected type '{0}', not type '{1}'", T.ToString(), bar.GetType().ToString()); } //Process downcasted object. Process(downcasted_bar); } } Then subclasses of FooBase would look like this... public class Foo_impl1 : FooBase<Bar_impl1> { void override Process(Bar_impl1 bar) { //No need to downcast here! } } Obviously this won't provide me compile time Type Checking, but I think it will get the job done... Questions: 1. Will this function as I think it will? 2. Is this the best way to do this? 3. What are the issues with doing it this way? 4. Can you suggest a different approach? Thanks!

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  • What's the deal with Java's public fields?

    - by Annan
    I've been reading two articles (1)(2) on javaworld.com about how all class fields should be private and getter/setter methods are just as bad. An object should act on the data it has rather than allowing access to it. I'm currently working on a University assignment for Connect Four. In designing the program the Agents playing the Game need access to the Board's state (so they can decide what to move). They also need to pass this move to the Game so it can validate it as a legal move. And during deciding what to move pieces are grouped into Threats with a start and end Points. Board, Threat and Point objects don't really do anything. They are just there to store related data that can be accessed in a human readable way. At the start of design I was representing Points on the board as two element int arrays, however that got annoying when creating points or referencing components of them. So, the class: public class Point { public int x; public int y; public Point(int x, int y){ this.x = x; this.y = y; } } Perfect in every way I can think of. Except it breaks every rule I've learned. Have I sinned?

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  • Bug in the official Android Fragments training sample?

    - by Jeff Axelrod
    It seems to me that there must be a bug in the Android Fragments demo. As background, Fragments are apparently sometimes instantiated by the Android OS and thus need a public no-arg constructor: All subclasses of Fragment must include a public empty constructor. The framework will often re-instantiate a fragment class when needed, in particular during state restore, and needs to be able to find this constructor to instantiate it. If the empty constructor is not available, a runtime exception will occur in some cases during state restore. But the NewsReader demo from the official Android training on Fragments constructs the HeadlinesFragment class and configures it with setOnHeadlineSelectedListener(this) from NewsReaderActivity.onCreate(). If the Android OS re-instantiates this fragment, the mHeadlineSelectedListener field will be null because HeadlinesFragment doesn't save or restore its state. Is this a bug or am I missing something?

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