Java checkers check if player clicked on enemy [duplicate]

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• Why does my if condition not accept an integer in java? 7 answers

Hi I'm working on a simple checkers and I have a problem with checking if the player clicked on the enemy. When player moves it seems as if the condition if(valid_position = true) is always true so the player can move to the position of an enemy. It might be a problem with for-loop setting it to true.

int mouse_x;
int mouse_y;
int selectedI;    
boolean valid_position = true;
ArrayList<Integer> playerX = new ArrayList<>();
ArrayList<Integer> playerY = new ArrayList<>();
ArrayList<Integer> kingX = new ArrayList<>();
ArrayList<Integer> kingY = new ArrayList<>();
ArrayList<Integer> enemyX = new ArrayList<>();
ArrayList<Integer> enemyY = new ArrayList<>();

public void mousePressed(MouseEvent e) {
    mouse_x = (e.getX()-3)/64;        
    mouse_y = (e.getY()-23)/64;   
    if(player_move = true){                
        for (int i = 0;  i < enemyX.size();  i++){
            if((enemyX.get(i) == mouse_x)&&(enemyY.get(i) == mouse_y)){
                valid_position = false;
                System.out.println("enemy");
                break;
            }
        }
        for (int i = 0;  i < playerX.size();  i++){
            if((playerX.get(i) == mouse_x)&&(playerY.get(i) == mouse_y)){
                selectedI = i;
                valid_position = true;
                System.out.println("player");
                break;
            }
        }            
        if(valid_position = true){
            if((mouse_x == playerX.get(selectedI)-1 && mouse_y == playerY.get(selectedI)-1) || (mouse_x == playerX.get(selectedI)+1 && mouse_y == playerY.get(selectedI)-1)){
                if(mouse_y == 0){
                    kingX.add(mouse_x);
                    kingY.add(mouse_y);
                    playerX.remove(selectedI);
                    playerY.remove(selectedI);
                }else{
                    playerX.set(selectedI,mouse_x);
                    playerY.set(selectedI,mouse_y);
                }                    
            }     
        }
    }
}