So I am using processing- similar to Java. I have made a button where I can add more ellipses (max 4) or press a different button to remove ellipses. I also made 4 different sets of keys for each of those ellipses to move. However, they can only move individually but not at the same time. I don't know the problem. Please help me. Thank you.

final static int N1= 1;                           //players can move at the same time
    final static int S1 = 2;                           
    final static int E1 = 4;                           
    final static int W1 = 8;                           // Speed limit. Round out edges for field (silhouette)
                                                  // if time Collision detection

    final static int N2 = 16;
    final static int S2 = 32;
    final static int E2 = 64;
    final static int W2 = 128;


    final static int N3 = 256;
    final static int S3 = 512;
    final static int E3 = 1024;
    final static int W3 = 2048;

    final static int N4 = 4096;
    final static int S4 = 8192;
    final static int E4 = 16384;
    final static int W4 = 32768;

    int result,k;                                  //store key input and initial number of players on field
    float x1,x2,x3,x4,y1,y2,y3,y4,n,r;             //Decleare some useful variables


    boolean sketchFullScreen() {                        //Make full screen
    return true;
}



    void setup() {                                      //Basic setup
    size(displayWidth, displayHeight);                //Window size maximum
    noCursor();                                       //Hide mouse cursor
    frameRate(60);                                   //set the frame rate, can lower the rate for lower performent pc
    result = 0;
    k = 1;
    n = 8;                                            //initial movement speed
    r = 15;                                           //initial radius of bubble

    x1 = 2*width/3;                                    
    y1 = height/3; 
    x2 = 2*width/3;                                    //light dot initial position
    y2 = 2*height/3; 
    x3 = width/3;                                  
    y3 = height/3; 
    x4 = width/3;                                    
    y4 = 2*height/3;
}



    void draw() {                                        //Start drawing
    background(0);                                     //Black background(COMPLETELY BLACK)
    switch(result){   
    case N1: y1=y1-n; break;
    case E1: x1=x1+n; break;
    case S1: y1=y1+n; break;
    case W1: x1=x1-n; break;                            //create movement to the dot by reassigning the coordinates
    case N1|E1: y1=y1-n; x1=x1+n; break;                    
    case N1|W1: y1=y1-n; x1=x1-n; break;
    case S1|E1: y1=y1+n; x1=x1+n; break;
    case S1|W1: y1=y1+n; x1=x1-n; break;

    case N2: y2=y2-n; break;
    case E2: x2=x2+n; break;
    case S2: y2=y2+n; break;
    case W2: x2=x2-n; break;                            //create movement to the dot by reassigning the coordinates
    case N2|E2: y2=y2-n; x2=x2+n; break;                    
    case N2|W2: y2=y2-n; x2=x2-n; break;
    case S2|E2: y2=y2+n; x2=x2+n; break;
    case S2|W2: y2=y2+n; x2=x2-n; break;

    case N3: y3=y3-n; break;
    case E3: x3=x3+n; break;
    case S3: y3=y3+n; break;
    case W3: x3=x3-n; break;                            //create movement to the dot by reassigning the coordinates
    case N3|E3: y3=y3-n; x3=x3+n; break;                    
    case N3|W3: y3=y3-n; x3=x3-n; break;
    case S3|E3: y3=y3+n; x3=x3+n; break;
    case S3|W3: y3=y3+n; x3=x3-n; break;

    case N4: y4=y4-n; break;
    case E4: x4=x4+n; break;
    case S4: y4=y4+n; break;
    case W4: x4=x4-n; break;                            //create movement to the dot by reassigning the coordinates
    case N4|E4: y4=y4-n; x4=x4+n; break;                    
    case N4|W4: y4=y4-n; x4=x4-n; break;
    case S4|E4: y4=y4+n; x4=x4+n; break;
    case S4|W4: y4=y4+n; x4=x4-n; break;
  }

    if(k>=5){k=4;}                                  //max bumber of players is 4
    if(k<0){k=0;}                                   //least amount of players is 0


    if(x1<0){x1=r/2;}
    else if(x1>displayWidth){x1=displayWidth-r/2;}
    if(x2<0){x2=r/2;}
    else if(x2>displayWidth){x2=displayWidth-r/2;}
    if(x3<0){x3=r/2;}
    else if(x3>displayWidth){x3=displayWidth-r/2;}
    if(x4<0){x4=r/2;}
    else if(x4>displayWidth){x4=displayWidth-r/2;}

    if(y1<0){y1=r/2;}
    else if(y1>displayHeight){y1=displayHeight-r/2;}
    if(y2<0){y2=r/2;}
    else if(y2>displayHeight){y2=displayHeight-r/2;}
    if(y3<0){y3=r/2;}
    else if(y3>displayHeight){y3=displayHeight-r/2;}
    if(y4<0){y4=r/2;}
    else if(y4>displayHeight){y4=displayHeight-r/2;}


    stroke(255);                                        //White light stroke
    if(k==1){ellipse(x1,y1,r,r);}                       //Draw an ellipse at location (x,y) xwith radius of 15 pixels
    if(k==2){
    ellipse(x1,y1,r,r); 
    ellipse(x2,y2,r,r);
        }

    if(k==3){
    ellipse(x1,y1,r,r); 
    ellipse(x2,y2,r,r);
    ellipse(x3,y3,r,r);
        }

    if(k==4){
    ellipse(x1,y1,r,r); 
    ellipse(x2,y2,r,r);
    ellipse(x3,y3,r,r);
    ellipse(x4,y4,r,r);
         }
}         


    void keyPressed() {
    switch(key) {
    case('w'):case('W'):result |=N1;break;
    case('d'):case('D'):result |=E1;break;
    case('s'):case('S'):result |=S1;break;              //classify the cases for the key pressed
    case('a'):case('A'):result |=W1;break;}
    switch(key) { 
    case('8'):result |=N2;break;
    case('6'):result |=E2;break;
    case('5'):result |=S2;break;              
    case('4'):result |=W2;break;}
    switch(key) {
    case('t'):case('T'):result |=N3;break;
    case('h'):case('H'):result |=E3;break;
    case('g'):case('G'):result |=S3;break;              
    case('f'):case('F'):result |=W3;break;}
    switch(key) {
    case('i'):case('I'):result |=N4;break;
    case('l'):case('L'):result |=E4;break;
    case('k'):case('K'):result |=S4;break;              
    case('j'):case('J'):result |=W4;break;}
    switch(key) {
    case('+'):case('='): n++;break;
    case('_'):case('-'): n--;break;                    //change movement speed
    case('['):case('{'): r=r-1;break;                  //change radius of bubble
    case(']'):case('}'): r=r+1;break;
    case(':'): k--;break;                            //add and take away players
    case('"'): k++;break;
  }
}

    void keyReleased(){  
    switch(key) {                                      
    case('w'):case('W'):result ^=N1;break;
    case('d'):case('D'):result ^=E1;break;
    case('s'):case('S'):result ^=S1;break;              //classify the cases for the key pressed
    case('a'):case('A'):result ^=W1;break;}
    switch(key) {  
    case('8'):result ^=N2;break;
    case('6'):result ^=E2;break;
    case('5'):result ^=S2;break;              
    case('4'):result ^=W2;break;}
    switch(key) {
    case('t'):case('T'):result ^=N3;break;
    case('h'):case('H'):result ^=E3;break;
    case('g'):case('G'):result ^=S3;break;              
    case('f'):case('F'):result ^=W3;break;}
    switch(key) {
    case('i'):case('I'):result ^=N4;break;
    case('l'):case('L'):result ^=E4;break;
    case('k'):case('K'):result ^=S4;break;              
    case('j'):case('J'):result ^=W4;break;} 
    switch(key) {    
    case('+'):case('='): n++;break;
    case('_'):case('-'): n--;break;
    case('['):case('{'): r=r-1;break;
    case(']'):case('}'): r=r+1;break;
  }
}

Processing is loosly based on Java, but the details of drawing things are very different, so I doubt that you will find your answer ina Java forum. Sorry.

Why not try Processing's own forum?
http://forum.processing.org/two/

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