MergeSort with ArrayList <card>

Question

import java.util.*;

public class Dealer {

public static void main(String[] args){
    ArrayList<Card> cards = new ArrayList<Card>();
        for (Suits s : Suits.values()) {
        for (Ranks r : Ranks.values()) {
             Card value = new Card(s,r);
             cards.add(value);
        }  
    }
    shuffle(cards);
    present(cards);
    System.out.println();
    cards = selectionSort(cards);
    present(cards);
}
private static void shuffle(ArrayList<Card> list){
     Collections.shuffle(list);
}
private static void present(ArrayList<Card> list){
    int count = 0;
    for (Card c : list){
        count++;
        System.out.println(c.toString());
    }
}
private static ArrayList<Card> selectionSort(ArrayList<Card> list){
    int min;
    int count = 0;
    for (int i = 0; i < list.size(); i++) {
        count++;
        // Assume first element is min
        min = i;
        for (int j = i + 1; j < list.size(); j++) {
            if (list.get(j).Get() < list.get(min).Get()) {
                min = j;



}
    }

if(min != i){
    final Card temp = list.get(i);
    list.set(i,list.get(min));
    list.set(min,temp);
}

  //  System.out.println(list.get(i));// I print the in ascending order
}
System.out.println("================================== Sorted Deck Below =========================================================");
System.out.println("It took "+count+" iterations to sort this deck using selection sort.");
System.out.println();
return list;

}

private static ArrayList<Card> InsertionSort(ArrayList<Card> list){
    int count = 0;
    for (int i = 1; i < list.size(); i++) {
        Card temp = list.get(i);
        int j;
        for(j = i-1;j>=0&&temp.Get()<list.get(j).Get(); j--){
            list.set(j+1,list.get(j));
        }
       list.set(j+1,temp); 
       count ++;
    }
    System.out.println("================================== Sorted Deck Below =========================================================");
    System.out.println("It took "+count+" iterations to sort this deck using insertion sort.");
    System.out.println();
    return list;
}


//mergeSort code below this is where I get confused on its implementation


public static void mergeSort(ArrayList<Card> list){
        if (list.size() ==1){
            return list;
        }
        else {
           int mid= list.size()/2;
           ArrayList<Card> left= new ArrayList<Card>(mid);
           ArrayList<Card> right=new ArrayList<Card>(list.size()-mid);



for (int i = 0; i < mid; i++) {
           left.add(list.get(i));
       }







for (int i = 0; i < list.size()-mid; i++) {
           right.add(list.get(i+mid));
       } 



left=mergeSort(left); 
   right=mergeSort(right);
   merge(left,right,list);
}
return list;

}


public static void merge (ArrayList<Card>left,ArrayList<Card>right,ArrayList<Card>list){
        int i1=0;// left Index
        int i2=0;// right Index
        int ListIndex=0;



for (int i = 0; i < list.size(); i++) {
        if (i2>=right.size() || (i1<left.size() && (right.get(i)>=left.get(i)))) 
        {
            list.set(ListIndex,left.get(i1));
            ListIndex++;
        }
        else {
            list.set(ListIndex, right.get(i2));
            ListIndex++;
        }
    }

}

}

=============================================== ============================

// Created enums
enum Ranks{
   Ace,King,Queen,Jack,Ten,Nine,Eight,Seven,Six,Five,Four,Three,Two
}

enum Suits{
    Spades,
    Hearts,
    Diamonds,
    Clubs
}

public class Card{

 private Ranks rank;
 private Cards card;

public Card(Suits suit, Ranks rank){


    this.suit = suit;
    this.rank = rank;
}

public int Get(){
     return (suit.ordinal())+rank.ordinal()*4;
}

public String toString(){


  return rank.toString()+" of " +suit.toString();
    }
}

我是使用ArrayList进行排序的初学者，但后来我看到这个代码有SelectionSort和InsertionSort然后我认为如果那两个在那里，那么我可以让MergeSort使用ArrayList做同样的事情。我理解它实际上会做什么但我对如何使用ArrayList实现它感到困惑。我在设置这些方法以处理ArrayList以使我的数组排序时遇到了麻烦。有谁知道我应该尝试纠正这个问题？我可以在这段代码的某些方面告诉我，很明显可以告诉某些部分会出现问题。为了澄清，我的主要问题是我如何能够为MergeSort方法实现ArrayList以正确地允许MergeSort对卡片进行排序？正如你所看到的那样，我确实尝试将ArrayList放在方法中，但我还没有真正成功地使用它。