ECSE202-Assignment 4 Solved

The simulation in Assignment 3 has no user interface, it simply runs according to a set of hardwired parameters.   In this assignment you will add a simple user interface as depicted below in Figure 1.

 

  

Figure 1

 

As can be seen in the figure, the simulation incorporates a JPanel that includes a means of entering simulation parameters.  Here sliders are being used in conjunction with IntFields and DoubleFields (similar to the Temperaure Conversion example in the notes).  When the user moves a slider, the corresponding value is echoed in the corresponding Int/Double field.  Similarly, when the user enters a number in the Int/Double field, the slider moves to a corresponding position.  Across the top a set of 4 JComboBoxes are implemented to minic a familiar user interface, but only the first is actually used by the program.  These allow the the user to select different features of the program (more below in Requirements).  Finally, there is a single JToggleButton at the bottom.  As its label implies, if pushed, the trace of each ball is plotted on the screen in the same color as the ball.  Together these features allow considerable flexibility over the program in Assignment 3.

             

Requirements
 

1. Functionality

 

Your program must allow the user to perform the following functions.  How you implement the User Interface is entirely up to you (e.g. JComboBox, push-buttons, etc.).  In other words, you do not have to replicate the example in Figure 1.

 

Run:    Starts a new simulation with parameters chosen from the current parameter set.              You should be able to run multiple simulations with new balls added to the display       at each Run instance.

Stack: Stacks all the balls created to date.  For example, assume that you have run a simulation  and stacked the balls.  Now you run another simulation and stack again.  This time all the balls in the previous stack are included in the current one.  As long as you have not created a new bTree, all balls will be included when stacked.

Clear: Clears the current display and kills the simulation attached to each ball.  If the simulation       is run again with new balls created, balls created previously are effectively eliminated.

Stop: Stops the current simulation, freezing the current display. Quit: Exits the program.

 

In addition, your program must include a Trace mode that can be enabled or disabled.  When enabled, the output resembles the output of Assignment 1 where a marker is placed at location traversed by the ball.  In this implementation the color of the “dot” should match the color of the ball it represents.  The display should be set up using with control functions laid across the top row, parameters along the right side of the display, and the Trace mode button at the bottom of the display.  This is most easily accomplished using the BorderLayout manager.  However you choose to implement selection, it must be event-driven so that the program reacts accordingly.

 

2. Parameter Entry

 

The key requirements are that i) all the parameters inputs should appear within a single JPanel that gets added to the display as shown, and ii) the user must be able to enter numerical parameters using the keyboard.   The example in Figure 1 is quite complex to implement as the program must respond to multiple event types.  The point here is to demonstrate what is possible.  

You can do this quite simply using Int/Double field boxes that generate ActionEvents (see the Temperature Conversion example in the notes).  By the way, you can also do this within GraphicsProgram, but a workaround is needed for it to work correctly (see below).

 

Implementation
 

Most of the work in this assignment is related to modifying bSim to incorporate user interface elements as well as re-packaging the simulation code and stacking code as methods that can be called from the user interface.  In particular, you should create a doSim() method that generates a set of balls, attaches them to the screen, and waits for the simulation to complete.  Rather than immediately proceeding to ball stacking on completion, doSim() should return.  Stacking functionality should be packaged as a method, doStack(), which traverses myTree and generates the appropriate display.  Unfortunately, if you try to call doSim() on an event, it will run, but not update the display.  This has to do with how GraphicsProgram is implemented and is beyond the scope of this course.  If you’re experienced writing Java code, then you can (if you haven’t already in Assignment 3) use a different framework outside of acm.  Otherwise, a workaround is shown below:

 

The usual way of handling a user selection would look something like the following:

 

1.     Restructure bSim so that the simulation component (generate the set of bBalls) is set up as a method that can be called more than once, e.g., doSim();

2.     Set up an entry for doSim() in a JComboBox or push button.

3.     Dispatch to doSim() when the corresponding entry is selected as shown below:

 

public void itemStateChanged(ItemEvent e) {

                        JComboBox source = (JComboBox)e.getSource();

                                                 

                        if (source==bSimC) {             \                                                                   

                                    if (bSimC.getSelectedIndex()==1) {                             System.out.println("Starting simulation");

                                                doSim();

                                    }

                                    else if (bSimC.getSelectedIndex()==2) {                                 System.out.println("Histogramming balls");

                                                doHist();

                                    }

                          etc…               } 
            }

 

 

Unfortunately, do to the way in which acm is implemented, your simulation will run, but not update the screen.  An inelegant solution to this problem is as follows:

 

public void init() {

            simEnable=false;                                                     // this is an instance variable

 

            …other code…

             

                        while(true) { 
                                    pause(200);

                                    if (simEnable) {                                  // Run once, then stop

                                                doSim();

                                                bSimC.setSelectedIndex(0);                             simEnable=false;

                                    }

                        }

}

 

The idea is to run the simulation from within the init() method rather than call it from itemStateChanged().  Variable simEnable allows the simulation to run exactly once if simEnable=true.

 

Back at itemStateChanged(), instead of calling doSim(), we simply change this to simEnable=true.  This method is referred to as polling – you will encounter it again in ECSE 211, Design Principles and Methods.