I have been playing with a bit of code I found on this site.
It creates a few rectangles that you can move around, add to and delete.

With regards to deleting an object in the ArrayList, Im having some slight issues.
In keyPressed(), under case 'd' I get a exception when I try to delete an object.
Obviously I use the wrong syntax, but bugger me if I can spot the correct way.

Any suggestions ?

1. 
   //================= Entity CLASS BEGIN =========================================
   class Entity
   {
     float x;
     float y;
     float destx;
     float desty;
     float speed;
     float movingAngle;
     boolean selected;
     boolean moving;
   
   
     //=========
     public Entity()
     {
       x = width/2;
       y = height/2;
       speed = 15;
       selected = moving = false;    //loses focus (selected) after moving
     }
   
     //========
     public void tick()
     {
       if (moving)
       {
         x += cos(movingAngle)*speed;
         y += sin(movingAngle)*speed;
   
         if (sqrt(sq(destx-x)+sq(desty-y)) <= speed)
         {
           moving = false;    //stops moving at destination
         }
       }
   
       // draw box with selected color dependin if box selected or not
       if (selected)
       {
         stroke(255);          //stroke param is colour in INT 0-255
         fill(255, 0, 0);      //fill param is v1, v2, v3 - float value
       }
   
       else
       {
         stroke(0);
         fill(0, 100, 200);
       } 
   
       rect(x, y, 50, 50);    //size of drawn square
     }
   
     //========
     public void goTo(float dx, float dy) {
       destx = dx;
       desty = dy;
       movingAngle = atan2(dy-y, dx-x);
       moving = true;
     }
   }
   
   //================= Entity CLASS END ==========================================
   
   
   //=============================================================================
   ArrayList entities;
   
   
   
   
   //=============================================================================
   //=============================================================================
   void setup() {
     size(800, 800);
     smooth();
     background(128);
   
     entities = new ArrayList();
     for (int i = 0; i< 5;i++)        // add the number of boxes in the loop (i) to the array list
     {
       entities.add(new Entity());    //adds a new box to the array (and screen)
     }
   }
   
   //=============================================================================
   void draw() {
     background(0);
   
     for (int i = 0; i< entities.size();i++)   //size get the lenght of the array
     {
       Entity e = (Entity)entities.get(i);
       e.tick();                              //does the tick on each "e" instance
     }
   }
   
   
   //=============================================================================
   void mousePressed() {
     //If no entity was pressed then we want them to move wherever the user clicked
     boolean entityPressed = false;
   
     //loop in reverse order so that if two square are on top of each other the one on top is selected
     for (int i = entities.size()-1; i>= 0 ;i--)
     {
       Entity e = (Entity)entities.get(i);
       if (mouseX > e.x && mouseX < e.x+50 && mouseY > e.y && mouseY < e.y+50)
       {
         entityPressed = true;
   
         if (e.selected)    
         {
           e.selected = false;
         }
   
         else              
         {
           e.selected = true;
         }
   
         break;      //break so that no other square are selected, this can be removed
       }
     }
   
     //No entity was pressed - move all selected entities to where the user clicked and unselect them.
     if (!entityPressed)
     {
       for (int i = 0; i< entities.size();i++)
       {
         Entity e = (Entity)entities.get(i);
         if (e.selected)
         {
           e.goTo(mouseX, mouseY);
           e.selected = false;    // unselect after moving
         }
       }
     }
   }
   
   
   
   void keyPressed ()
   //pressing "a" on the keyboard, generates a new box
   //press "d" and delete a box
   //press "e" and it deletes all the objects in the arrayList
   
   {
     switch(key)
     {
     case 'a':
       entities.add(new Entity());
       break;
   
     case 'd':
       if (entities.size() > 1)    //boundry check to ensure we do not delete past 1 object
       {
         //this doesn't work
         int x = entities.lastIndexOf();
         entities.remove(x);
        
        //the below works, but removes the wrong element, ie always object 1 and not the last one added
       //   entities.remove(1);
       }
       else
       {
         break;                  //do nothing
       }
       break;
   
     case 'e':
       entities.clear();
       break;
   
     default:
       break;
     }
   }
   
   

Im trying to create a 2D ArrayList but is having some issues

Currently I have a single list like this

ArrayList aObject;
.
.
aObject = new ArrayList();
  for (int i = 0; i< 5;i++)       
    {
    aObject.add(new Entity());    //Entity is a Class
    }

However I would like to be able to have a 2D (or possible 3D) ArrayList

Any suggestions ?

In C/C++ a static scope for a variable means that it has a ram address as opposed to a register address, so if you leave and re-enter the function, the variable data is preserved.

In java does the same apply ?

When I search I get a whole of non-compressible references, so i thought it might be easier just to ask a simple question

Ta

Where do I find reference to frame. properties

My search here does not show anything useful

Thanks

Are there any libraries to have a normal type window, ie sizable by dragging with mouse.

And is there a normal type dropdown "menu" library (ie File, Edit, Help etc) somewhere

My search didn't show anything

Hi

I would like to write a program which shows a 2x20 LCD display.
Each individual display is 5x8 pixel in size

is there a existing library for an LCD dotmatrix type display
Haven't been able to find one

Thanks