How to add up all the values in an ArrayList<String> or convert to ArrayList<Integer>-CodePudding

I'm trying to add up all the values inside of an ArrayList but nothing allows me to get the sum. I have to find the average of the numbers pulled from a text file.

public static void main(String[] args) throws IOException {
    File file = new File("C:\\Users\\[REDACTED]\\Desktop\\mbox.txt");
    Scanner inputFile = new Scanner(file);
    ArrayList<Integer> ConfidenceLevels = new ArrayList<>();
    String [] DSPAM;
    String line;
    
    while(inputFile.hasNext())
    {
        line = inputFile.nextLine();
        if(line.startsWith("X-DSPAM-Confidence:"))
        {
            DSPAM = line.split(" 0");
            int x = Integer.parseInt(DSPAM[1].trim());
            ConfidenceLevels.add(x);
        }
    }
    System.out.println(ConfidenceLevels);
    System.out.println(ConfidenceLevels.size());
}

CodePudding user response：

You can try use IntSummaryStatistics and you can get min/max/average/sum of this list.

    IntSummaryStatistics intSummaryStatistics = ConfidenceLevels.stream().mapToInt(Integer::intValue).summaryStatistics();
    System.out.println(intSummaryStatistics.getAverage());
    System.out.println(intSummaryStatistics.getMin());
    System.out.println(intSummaryStatistics.getMax());
    System.out.println(intSummaryStatistics.getSum());

CodePudding user response：

You are just adding elements to the list. If you want the sum of them, you can create an Integer variable and add it.

public static void main(String[] args) throws IOException {
    File file = new File("C:\\Users\\[REDACTED]\\Desktop\\mbox.txt");
    Scanner inputFile = new Scanner(file);
    Integer confidenceLevelsSum = 0;
    String [] DSPAM;
    String line;
    
    while(inputFile.hasNext())
    {
        line = inputFile.nextLine();
        if(line.startsWith("X-DSPAM-Confidence:"))
        {
            DSPAM = line.split(" 0");

            // Check if it's null before trying to convert it.
            if (DSPAM[1] == null) {
                continue;
            }

            int x = Integer.parseInt(DSPAM[1].trim());
            confidenceLevelsSum  = x;
        }
    }
    System.out.println(confidenceLevelsSum);
}