從txt文件中讀取數字並進行比較

Question

使用此程序，我想閱讀並比較文本文件中給出的數字，並在數字連續三個時間上升時打印“購買” ，並在數字連續三個下降時打印“出售” 。

我的程序的問題在於，它僅讀取“ numbers.txt”的15行中的13行，並且買賣位置錯誤。

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Scanner;
import java.text.DecimalFormat;

public class Practise {
    public static void main(String[] args) throws IOException {
        int num = 0;
        int up = 0;
        int down = 0;
        int same = 0;
        FileInputStream file = new FileInputStream("numbers.txt");
        Scanner scanner = new Scanner(file);
        while (scanner.hasNextDouble()) {
            Double[] array = new Double[15];
            for (int i = 0; i < array.length; i++) {
                array[i] = scanner.nextDouble();
            }
            for (int a = 0; a < array.length && a + 1 < array.length - 1; a++) {
                num++;
                System.out.print(num + "  " + (array[a]));
                if (array[a] < array[a + 1]) {
                    up++;
                } else if (array[a] > array[a + 1]) {
                    down++;
                } else {
                    same++;
                }
                if ((up >= 3 && (down > 1 || same >= 1))) {
                    System.out.print("  " + "sell");
                    up = 0;
                    same = 0;
                } else if ((down >= 3 && (up > 1 || same >= 1))) {
                    System.out.print("  " + "buy");
                    down = 0;
                    same = 0;
                }
                System.out.println();
            }
        }
    }
}

文件numbers.txt：

26.375
25.500
25.125
25.000
25.250
27.125
28.250
26.000
25.500
25.000
25.125
25.250
26.375
25.500
25.500

預期產量：

1 26.375
2 25.500
3 25.125
4 25.000
5 25.250購買
6 27.125
7 28.250
8 26.000賣出
9 25.500
10 25.000
11 25.125購買
12 25.250
13 26.375
14賣出25.500
15 25.500

Answer 1

您使用a + 1 < array.length - 1 ，可以將其轉換為a < array.length - 2 。 我想您知道&&中的第二個操作數將迭代限制為13。

a < array.length && a < array.length - 2 = a < 15 && a < 13 = a < 13

我對您的代碼做了一些小的更改，以使其正常工作； 您可以對其進行很多重構，但是我堅持使用您的樣式，因此您可以更好地理解其邏輯。

    int num = 1;
    //print the 1st element
    System.out.println(num + "  " + array[0]);
    for (int a = 1; a < array.length; a++) {
        num++;
        System.out.print(num + "  " + (array[a]));
        //plz note that we check with the before, not after
        if (array[a] < array[a - 1]) {
            down++;
        } else if (array[a] > array[a - 1]) {
            up++;
        } else {
            same++;
        }
        //changed down > to down ==
        if ((up >= 3 && (down == 1 || same >= 1))) {
            System.out.print("  " + "sell");
            up = 0;
            same = 0;
        } 
        //changed up > to up ==
        else if ((down >= 3 && (up == 1 || same >= 1))) {
            System.out.print("  " + "buy");
            down = 0;
            same = 0;
        }
        System.out.println();
    }

回答操作者評論：如果您要支持15條以上的記錄，則可以繼續添加到列表中：

List<Double> list = new ArrayList<>();
while (scanner.hasNextDouble()) {
    list.add(scanner.nextDouble());
}
//if you want to work with array
Double[] array = new Double[list.size()];
array = list.toArray(array);

Answer 2

這是一個工作示例（必須將數組更改為列表）

int num = 0, up = 0, down = 0, same = 0;

FileInputStream file = new FileInputStream("numbers.txt");
Scanner scanner = new Scanner(file);
List<Double> list = new ArrayList<>();

while (scanner.hasNextDouble()) {
    list.add(scanner.nextDouble());
}

int position = 0;

while (position + 2 < list.size()) {
    Double[] nums = new Double[3];

    System.out.println(nums[0] = list.get(position));
    System.out.println(nums[1] = list.get(position + 1));
    System.out.println(nums[2] = list.get(position + 2));

    if (nums[1] > nums[0] && nums[2] > nums[1]) {
        System.out.println("buy");
        up++;
    } else if (nums[1] < nums[0] && nums[2] < nums[1]) {
        System.out.println("sell");
        down++;
    } else {
        same++;
    }
    position += 2;
}
System.out.println("Ups total: " + up);
System.out.println("Downs total: " + down);
System.out.println("Same total: " + same);