在ArrayList中累計數字不顯示

Question

我想輸出文本文件中的一些數字的總數，使用ArrayList來尋找它們等，我不確定我會如何做到這一點？這裏是我的代碼：

import java.io.File; 
import java.io.FileNotFoundException; 
import java.util.ArrayList; 
import java.util.Scanner; 

public class ArrayListOfNumbers { 

    public static void main(String[] args) throws FileNotFoundException { 
     ArrayList<String> numbers = new ArrayList<String>(); 
     Scanner Scan = new Scanner (new File("numbers.txt")); 

     while (Scan.hasNext()){ 
      numbers.add(Scan.nextLine()); 
     } 
     for(int i = 0; i < numbers.size(); i++){ 
      System.out.println(numbers.get(i)); 
     } 

     System.out.println("") 

     Scan.close(); 
    } 

} 

Answer 1

public static void main(String[] args) throws FileNotFoundException { 
     Scanner Scan = new Scanner (new File("numbers.txt")); 
     double sum = 0; 
     while (Scan.hasNext()){ 
      sum += Double.parseDouble(Scan.nextLine()); 
     } 

     System.out.println(sum); 

     Scan.close(); 
    }