Slick2D-Beginner-Logic Problem

Hey together,

I just started to try to build something with the Slick-API.
As I faced some problems, I won´t get the solution for those two:

I have a Player (me) represented with a green Circle and 1-10 red Circles, which are supposed to be the Enemies.
The Enemy-Circles are “attracted” by the Player and come closer. Now I wanted the Player-Circle move to the closest
Enemy-Circle. And after “killing” this one, moving to the next-closest.
My idea goes like this (and it works sometimes), but after “killing” all Enemy-Circles except the last one my Player-Circle stops.
Also it sometimes does crazy things.
How do I fix this? Any suggestions?

for (int e = 0; e < enemies.size(); e++) {
				for (int j = 1; j < enemies.size(); j++) {
					//Nächsten Enemy herausfinden
					//X+Y
					if (Math.abs(actX - actXEn[e]) > Math.abs(actX - actXEn[j])) {

						prefX = actXEn[j];
						player1.move(player1, WIDTH, HEIGHT, delta, prefX, prefY);
					}
					if (Math.abs(actX - actXEn[e]) < Math.abs(actX - actXEn[j])) {

						prefX = actXEn[e];
						player1.move(player1, WIDTH, HEIGHT, delta, prefX, prefY);
					}
					if (Math.abs(actY - actYEn[e]) > Math.abs(actY - actYEn[j])) {

						prefY = actYEn[j];
						player1.move(player1, WIDTH, HEIGHT, delta, prefX, prefY);
					}
					if (Math.abs(actY - actYEn[e]) < Math.abs(actY - actYEn[j])) {

						prefY = actYEn[e];
						player1.move(player1, WIDTH, HEIGHT, delta, prefX, prefY);
					}
				} 

			}
			actX = (int) player1.getShape().getX();
			actY = (int) player1.getShape().getY();
		}

A general problem/question. How do I build-in something like another window in my actual playing-panel. I need something to
place new Circles, while in-game.

Thank you so much!