1. int[] input = new int[100];
2. for(int i=0; i<input.length;i++){
3.   input[i]=i+1;
4. }
5. int target = 65;
6. int[] output = new int[25];
7. int counter=0;
8. for(int i=-20;i<30;i+=10){
9.   for(int j=-2;j<3;j++){
10.     output[counter] = input[target-1+i+j];
11.     counter++;
12.   }
13. }
14. String toPrint = "";
15. for( int i=0; i<output.length;i++){
16.   toPrint += "" + output[i] + " ";
17. }
18. println( toPrint );

1. import java.util.List;
   import java.util.Arrays;
   Integer[] output = new Integer[25];
   Integer[] output_dest = new Integer[25];
   int px, target;
   void setup()
   {
     size(500, 500);
     textSize(30);
     output_dest= output;
     px = target;
   }
   void draw()
   {  
     background(0);
     fill(0, 255, 0);
     text(target, width/2, height/2);
     Integer[] input = new Integer[100];
     for (int i=0; i<input.length;i++) {
       input[i]=i+1;
     }
   
     target = int(constrain(map(mouseX, 0, 500, 0, 100), 23, 77));
   
     if (px != target) //when target changes.
     {
   
       int counter=0;
       for (int i=-20;i<30;i+=10) {
         for (int j=-2;j<3;j++) {
           output[counter] = input[target-1+i+j];
           counter++; //create the array of Integer.
         }
       }
       String toPrint = "";
       for ( int i=0; i<output.length;i++) {
         toPrint += "" + output[i] + " ";
       }
       println( "output===="+toPrint ); //this is where the list is done
   
   
       List<Integer> newItems = new ArrayList<Integer>(Arrays.asList(output_dest));
       newItems.removeAll(Arrays.asList(output));
       List<Integer> formerItems = new ArrayList<Integer>(Arrays.asList(output));
       formerItems.removeAll(Arrays.asList(output_dest));
       System.out.println("New items: " + newItems);
       System.out.println("Former items: " + formerItems);
       px = target;
       //    String toPrint2 = "";
       //    for ( int i=0; i<output_dest.length;i++) {
       //      toPrint2 += "" + output_dest[i] + " ";//unfortunately output_dest is always equal to output, I don't understand why.
       //    }
       //    println( "output_DEST===="+toPrint2 );
       output_dest =output ; //should make the difference between output and output_dest to track new and former items.
     }
   }
   

sorry for this non really interesting topic  but thank you in advance for any help.