試圖以升序反轉我的流-Java8

這段代碼背后的想法是，它從三個.csv按年份組織的帶有鍵的檔案中讀取資料，并按年份檢索資料的總和，以及每年的最小和最大數量。

問題是，列印時它按降序回傳年度結果。

我需要幫助找出一種反轉流的方法，以便每個檔案的年度資料按升序排列。

public class SalesGenerator {
    
    //This class will print out the Maximum and minimum Sales data from the .getSales() in TeslaImport.
    public static void teslaReport(
        Set<Entry<String, List<TeslaImport>>> entrySet, 
        List<TeslaImport> teslaModel, String modelName) 
    throws IOException {        
        //This comparator will sort the sales array values.
        Comparator<TeslaImport> comparativeOperator = Comparator.comparing(tesla -> tesla.getSales());

        entrySet.stream().forEach(entry -> System.out.println(
            "Month: "   entry.getKey()   " -> " 
              entry.getValue().stream()
                .mapToInt(tesla -> tesla.getSales().intValue())
                .sum()
        ));
        
        TeslaImport maximumSales = teslaModel.stream()
            .max(comparativeOperator)
            .orElseThrow(NoSuchElementException::new);
        TeslaImport minimumSales = teslaModel.stream()
            .min(comparativeOperator)
            .orElseThrow(NoSuchElementException::new);
            
        //Print out the maximum and minimum results from TeslaReport.
        System.out.println(modelName   " Yearly Sales Report");
        System.out.println("The BEST month for "   modelName   " was: "   maximumSales.getDate());
        System.out.println("The WORST month for "   modelName   " was: "   minimumSales.getDate());                                                                                 
    } 
    
    public static void main(String[] args) throws IOException {
        
        /* To produce the sales values from TeslaData, we need to instantiate the TeslaData variable to import
        all the EntrySet models */
        TeslaData analysedData = new TeslaData();
        
        /*The FileReader from our FileGenerator class needs to be instantiated to model3. We can use to when
        when reporting our data in TeslaReport */
        List<TeslaImport> model3 = FileGenerator.teslaFileRead("model3.csv");
        Set<Entry<String, List<TeslaImport>>> entrySetModel3 = analysedData.entryByYear(model3);
        teslaReport(entrySetModel3, model3, "Model 3");
        
        /*The FileReader from our FileGenerator class needs to be instantiated to modelS. We can use to when
        when reporting our data in TeslaReport */
        List<TeslaImport> modelS = FileGenerator.teslaFileRead("modelS.csv");
        Set<Entry<String, List<TeslaImport>>> entrySetModelS = analysedData.entryByYear(modelS);
        teslaReport(entrySetModelS, modelS, "Model S");
        
        /*The FileReader from our FileGenerator class needs to be instantiated to modelX. We can use to when
        when reporting our data in TeslaReport */
        List<TeslaImport> modelX = FileGenerator.teslaFileRead("modelX.csv");   
        Set<Entry<String, List<TeslaImport>>> entrySetModelX = analysedData.entryByYear(modelX);        
        teslaReport(entrySetModelX, modelX, "Model X");
    }
}

注： TeslaImport在這里我把我的班JavaBean中的（get/set，toString，date和sales）

uj5u.com熱心網友回復：

entryByYear由于為從類中的方法檢索的條目集列印報告資料TeslaModel，因此該方法很可能回傳按降序排序的樹形圖的條目集。因此，要更改順序，應按鍵重新排序流：

entrySet.stream()
    .sorted(Map.Entry.comparingByKey())
    .forEach(entry -> System.out.println(
            "Month: "   entry.getKey()   " -> " 
              entry.getValue().stream()
                .mapToInt(tesla -> tesla.getSales().intValue())
                .sum()
        ));

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