java - 为什么我会出现 0 的无限循环？ ( java )

Question

前几天我问了一个关于我的代码的问题，这个问题很快就被这里令人难以置信的社区解决了。然而，我使用代码的重写版本遇到了一个完全独立的问题。这是我上一篇文章中对该程序的描述。

I'm trying to write a program that can detect the largest sum that can be made with any subset of numbers in an ArrayList, and the sum must be lower than a user-input target number. My program is working flawlessly so far, with the exception of one line (no pun intended). Keep in mind that this code isn't complete yet too.

我现在的代码问题是，在用户输入目标数字后，程序输出一个0的无限循环。即使在尝试调试之后，我仍然遇到问题。 ArrayList 完美地应用于程序，但我认为我的 while 循环之一中可能存在问题。有什么想法吗？

这是代码。

import java.util.*;
class Sum{
    public static void main(String[] args){
        Scanner input = new Scanner(System.in);
        int temp = 0, target = 1, result = 0, firstIndex = 0, secondIndex = 0;
        String tempString = null;
        ArrayList<String> list = new ArrayList<String>();
        ArrayList<Integer> last = new ArrayList<Integer>();
        System.out.println("Enter integers one at a time, pressing enter after each integer Type \"done\" when finished.\nOR just type \"done\" to use the default list.");
        String placehold = "NotDone";

        while (!placehold.equals("done")){
            list.add(input.nextLine());
            placehold = list.get(list.size() - 1);
        }
        list.remove(list.size() - 1);
        if (list.size() == 0){            //Inserts default list if said list is empty
            list.add("1");
            list.add("2");
            list.add("4");
            list.add("5");
            list.add("8");
            list.add("12");
            list.add("15");
            list.add("21");
        }
        for (int i = 0; i < list.size(); i++){
            tempString = list.get(i);
            temp = Integer.parseInt(tempString);     //Changes the items in the list to Integers, which can be inserted into another list and then sorted
            last.add(temp);
        }
        Collections.sort(last);
        System.out.println("Enter the target number");
        target = input.nextInt();
        while (result < target){
            firstIndex = last.size() - 1;
            secondIndex = firstIndex - 1;
            while (last.get(firstIndex) > target){
                firstIndex--;
            }
            if (last.get(firstIndex) + last.get(secondIndex) < result){
                result = last.get(firstIndex) + last.get(secondIndex);
                last.remove(firstIndex);
                last.remove(secondIndex);
                last.add(result);
            }
            else{
                secondIndex--;
            }
            System.out.println(result);
        }  
    }
}

以及输出...

Enter integers one at a time, pressing enter after each integer Type "done" when finished. OR just type "done" to use the default list.

done //Prompting to use the default list

Enter the target number

15 //User inputs target number

0 0 0 0 0 0 ... //And so on

Answer 1

target = input.nextInt();

应该在循环内，否则变量将永远不会改变

while(result<target)永远不会变成假

<小时/>

while(result<target) {
    target = input.nextInt();
    // otherCoolCode
}