如何获取先前的ArrayList值？

Question

以下是项目的ArrayList：

项目1：（重量：4，利润：5）
第2项：（重量：10，利润：12）
第3项：（重量：5，利润：8）

和容量= 11和随机位翻转（如果0将变为1，反之亦然）：
orderList = [2,0,1]。

我的代码：

'

public class BitString { 
    public static void main (String[] args){ 
    int n = 3, capacity = 11, pointer, toFlip; 

    ArrayList<Item> itemList = new ArrayList<Item>(); 
    ArrayList<Integer> solution = new ArrayList<Integer>(); 
    ArrayList<Integer> currentSolution = new ArrayList<Integer>(); 
    ArrayList<Integer> flipOrder = new ArrayList<Integer>(); 
    ArrayList<ArrayList<Integer>> improve = new ArrayList<ArrayList<Integer>>(); 

    itemList.add(new Item(4,5)); 
    itemList.add(new Item(10,12)); 
    itemList.add(new Item(5,8)); 

    solution = initialSolution(n); 
    currentSolution = solution; 
    flipOrder = randomFlipOrder(n); 

    System.out.println("List of Items: " + itemList); 
    System.out.println("Initial solution: " + solution); 
    System.out.println("Current solution: " + currentSolution); 
    System.out.println("Random order: " + flipOrder); 

    for (int i = 0; i < flipOrder.size(); i++){ 
     int totalWeight = 0, totalProfit = 0; 

     pointer = flipOrder.get(i); 
     toFlip = solution.get(pointer); 

     System.out.println(); 

     for (int j = 0; j < solution.size(); j++){ 
      if (solution.get(j) == 1){ 
       totalWeight += itemList.get(j).getWeight(); 
       totalProfit += itemList.get(j).getProfit(); 
      } 
     } 

     System.out.println("Total Weight For Solution " + solution + " : " + totalWeight + " | Total Profit For Solution " + solution + " : " + totalProfit); 

     if (totalWeight <= capacity){ 
      System.out.println(totalWeight + " NOT EXCEED CAPACITY FOR SOLUTION: " + solution); 
      currentSolution = solution; 
      improve.add(currentSolution); 
      System.out.println("Updated Current Solution: " + solution); 
      System.out.println("Updated Improved: " + improve); 

      //do the flipping bits 
      if (toFlip == 1) 
       solution.set(pointer, 0); 
      else 
       solution.set(pointer, 1); 

      System.out.println("New Solution After flip: " + solution); 
      //improve.remove(0); 
     } 
     else{ 
      System.out.println(totalWeight + " EXCEEDS CAPACITY FOR SOLUTION: " + solution); 
      //solution = currentSolution; 
      System.out.println("SOLUTION REVERTED: " + improve.get(0)); 

      //do the flipping bits 

      if (toFlip == 1) 
       solution.set(pointer, 0); 
      else 
       solution.set(pointer, 1); 

      System.out.println("New Solution After flip: " + solution); 
     } 

    } 

} 

//generate initial solution(bits) randomly 
public static ArrayList<Integer> initialSolution(int length){ 
    Random r = new Random(); 
    ArrayList<Integer> solution = new ArrayList<Integer>(length); 

    // generate some random boolean values 
    boolean[] booleans = new boolean[length]; 
    for (int i = 0; i < booleans.length; i++) { 
     booleans[i] = r.nextBoolean(); 
    } 

    for (boolean b : booleans) { 
     if (b == true){ 
      solution.add(1); 
     } 
     else{ 
      solution.add(0); 
     } 
    } 

    return solution; 

} 

public static ArrayList<Integer> randomFlipOrder(int length){ 
    ArrayList<Integer> order = new ArrayList<Integer>(); 
    Random r = new Random(); 

    for (int i = 0; i < length; i++){ 
     order.add(i); 
    } 

    Collections.shuffle(order); 

    return order; 
    } 
    } 

'

具有生成随机比特串。
例如：[0,1,0]意味着项目2取和给予总重量= 10。

因此，如果总重量< =容量然后保持[0,1,0]在数组列表。

然后，我需要翻转索引2的比特（基于orderList）：
例如：[0,1,1]意味着项目2 & 3取出并给予总重量= 15。

我想收回存储[0,1,0]和从先前的值工作的先前值：
[0,1,0] =>下一个比特是倒装在索引0处，并bcomes [1,1,0]而不是采取最新（超容量）[0,1,1]并翻转它[1,1,1]。

但是我不断收到更新的值，并且无论何时超过容量都无法获取先前的值。

我的输出： Output Image

Answer 1

如何获得.SET后以前的ArrayList（）的值用的？

你不能，除非你有使用new ArrayList<Integer>(myListToBackup)