我的数组只记住最后输入的最后一个元素，直方图打印不正确

Question

import java.util.Scanner;

public class RainRecording {

    private int choice;
    private Scanner input;
    private String site;
    private int days;
    private int daysCounter;
    private int[] rainRecorded;
    private int[] rainEntered;
    private float lattitude;
    private float longitude;
    private String message1;
    private String message2;
    private String message3;
    private String message4;
    private String message5;
    private String message6;

    // declare name of variable

    public RainRecording() {

        // declare value of variable

        this.message1 = "Site";
        this.message2 = "lattitude";
        this.message3 = "longitude";
        this.message4 = "Window";
        this.message5 = "days";
        this.message6 = ":";
        this.daysCounter = 0;
        this.input = new Scanner(System.in);
        mainMenu();

    }

    private void mainMenu() {
        System.out.println("");
        System.out.println("*** Rain Gauge Menu ***");
        System.out.println("  1: Create rain gauge");
        System.out.println("  2: Display rain gauge details");
        System.out.println("  3: Add daily rainfall measurement");
        System.out.println("  4: Display rainfall histogram");
        System.out.println("  5: Get maximum rainfall");
        System.out.println("  6: Check rainfall is below threshold");
        System.out.println("  7: Display anaylsis");
        System.out.println("  8: Exit");
        System.out.print("Please enter your selection: ");

        Chosen();

    }

    private void Chosen() {

        this.choice = Integer.parseInt(input.nextLine());
        switch (choice) {
        case 1:
            createGauge();
            break;

        case 2:

            gaugeDetails();
            break;
        case 3:
            
            int i = 0;

            while( i < this.days || this.daysCounter == this.days) {
            
            if (this.daysCounter == this.days) {

                System.out.printf("Error - system full\n");
                mainMenu();

            }
            if (this.days < 1) {

                mainMenu();

            } else {        
                

                this.rainRecorded = new int[this.days];
                System.out.printf("Please enter rainfall for the current day:  ");
                rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
                this.daysCounter++;
                this.rainEntered = new int[this.daysCounter];
                mainMenu();
            }
            
            i++;
            }
            break;
        case 4:
            System.out.printf("\n");
            displayHistogram();
            break;
        case 5:
            break;
        case 6:
            break;
        case 7:
            break;
        case 8:
            break;

        default:
            System.out.println("Invalid input, try again");
            mainMenu();
        }

        while (choice != 8)
            ;

    }

    

    private void createGauge() {

        System.out.printf("\nPlease enter the name of the site :");
        this.site = input.nextLine();
        System.out.printf("Please enter the number of days to record :");
        this.days = Integer.parseInt(input.nextLine());
        System.out.printf("Please enter the lattitute :");
        this.lattitude = Float.parseFloat(input.nextLine());
        System.out.printf("Please enter the longitude :");
        this.longitude = Float.parseFloat(input.nextLine());
        mainMenu();

    }

    private void gaugeDetails() {

        if (this.days > 0) {

            System.out.printf("%-9s %-3s %s \n", this.message1, this.message6, this.site);
            System.out.printf("%s %-3s % 09.4f\n", this.message2, this.message6, this.lattitude);
            System.out.printf("%s %-3s %9.4f\n", this.message3, this.message6, this.longitude);
            System.out.printf("%-9s %-3s %-2d%s \n", this.message4, this.message6, this.days, this.message5);

            mainMenu();

        } else {

            mainMenu();

        }

    }

    private void displayHistogram() {

        for (int i = 0; i < this.rainEntered.length; i++) {

            for (int j = 0; j < this.rainRecorded[i] - 1; j++) {

                System.out.print("*");

            }

            System.out.println(i);

        }

        System.out.print("");
        mainMenu();

    }

    public static void main(String[] args) {

        @SuppressWarnings("unused")
        RainRecording objName;
        objName = new RainRecording();

    }

}

伙计们，我在我的 switch 语句中被打了几天，以防万一 3 是我创建要输入数组的元素的地方，但似乎只记得当我打印直方图时输入的最后一个数组情况 4 displayHistogram();这也是我的直方图打印错误的地方。 所以问题是我的数组没有记录属性并且直方图打印错误。 例如用户选择输入 3 天，值为 10,20,30，当我打印直方图时，它会打印这个。

0    
1  
*****************************2

下面是我想要的，一个 * 永远有十天的雨，首先打印索引。

0 *              
1 **  
2 **  

Answer 1

您需要将this.rainRecorded 的初始化移动到createGauge 方法并根据需要更新displayHistogram 以打印。您可以尝试以下方法：

import java.util.Scanner;

public class RainRecording {

  private int choice;
  private Scanner input;
  private String site;
  private int days;
  private int daysCounter;
  private int[] rainRecorded;
  private int[] rainEntered;
  private float lattitude;
  private float longitude;
  private String message1;
  private String message2;
  private String message3;
  private String message4;
  private String message5;
  private String message6;

  // declare name of variable

  public RainRecording() {

    // declare value of variable
    
    this.message1 = "Site";
    this.message2 = "lattitude";
    this.message3 = "longitude";
    this.message4 = "Window";
    this.message5 = "days";
    this.message6 = ":";
    this.daysCounter = 0;
    this.input = new Scanner(System.in);
    mainMenu();
  }

  private void mainMenu() {
    System.out.println("");
    System.out.println("*** Rain Gauge Menu ***");
    System.out.println("  1: Create rain gauge");
    System.out.println("  2: Display rain gauge details");
    System.out.println("  3: Add daily rainfall measurement");
    System.out.println("  4: Display rainfall histogram");
    System.out.println("  5: Get maximum rainfall");
    System.out.println("  6: Check rainfall is below threshold");
    System.out.println("  7: Display anaylsis");
    System.out.println("  8: Exit");
    System.out.print("Please enter your selection: ");
    Chosen();
  }

  private void Chosen() {
    this.choice = Integer.parseInt(input.nextLine());
    switch (choice) {
      case 1:
        createGauge();
        break;
      case 2:
        gaugeDetails();
        break;
      case 3:
        int i = 0;
        while( i < this.days || this.daysCounter == this.days) {
          if (this.daysCounter == this.days) {
            System.out.printf("Error - system full\n");
            mainMenu();
          }
          if (this.days < 1) {

            mainMenu();

          } else {
            System.out.printf("Please enter rainfall for the current day:  ");
            rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
            this.daysCounter++;
            this.rainEntered = new int[this.daysCounter];
            mainMenu();
          }

          i++;
        }
        break;
      case 4:
        System.out.printf("\n");
        displayHistogram();
        break;
      case 5:
        break;
      case 6:
        break;
      case 7:
        break;
      case 8:
        break;
      default:
        System.out.println("Invalid input, try again");
        mainMenu();
    }
    while (choice != 8)
      ;
  }



  private void createGauge() {
    System.out.printf("\nPlease enter the name of the site :");
    this.site = input.nextLine();
    System.out.printf("Please enter the number of days to record :");
    this.days = Integer.parseInt(input.nextLine());
    this.rainRecorded = new int[this.days]; // move the array initialization here
    System.out.printf("Please enter the lattitute :");
    this.lattitude = Float.parseFloat(input.nextLine());
    System.out.printf("Please enter the longitude :");
    this.longitude = Float.parseFloat(input.nextLine());
    mainMenu();
  }

  private void gaugeDetails() {
    if (this.days > 0) {
      System.out.printf("%-9s %-3s %s \n", this.message1, this.message6, this.site);
      System.out.printf("%s %-3s % 09.4f\n", this.message2, this.message6, this.lattitude);
      System.out.printf("%s %-3s %9.4f\n", this.message3, this.message6, this.longitude);
      System.out.printf("%-9s %-3s %-2d%s \n", this.message4, this.message6, this.days, this.message5);
      mainMenu();
    } else {
      mainMenu();
    }
  }

  private void displayHistogram() {
    for (int i = 0; i < this.rainEntered.length; i++) {
      System.out.print(i + " ");
      for (int j = 0; j < this.rainRecorded[i] - 1; j += 10 ) {
        System.out.print("*");
      }
      System.out.println();
    }
    mainMenu();
  }

  public static void main(String[] args) {
    @SuppressWarnings("unused")
    RainRecording objName;
    objName = new RainRecording();
  }

}

Answer 2

所以，你的代码有点过头了，我在试图理解基本意图时遇到了一些问题，例如

private int[] rainRecorded;
private int[] rainEntered;

我不确定这两个变量的意图是什么。所以在我的例子中，我暂时放弃了rainEntered。

所以，你的第一个问题从这里开始......

while( i < this.days || this.daysCounter == this.days) {

    if (this.daysCounter == this.days) {

        System.out.printf("Error - system full\n");
        mainMenu();

    }
    if (this.days < 1) {

        mainMenu();

    } else {        
        

        this.rainRecorded = new int[this.days];
        System.out.printf("Please enter rainfall for the current day:  ");
        rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
        this.daysCounter++;
        this.rainEntered = new int[this.daysCounter];
        mainMenu();
    }
    
    i++;
}

首先，我将删除两个退出条件的需要，因为这会使推理变得更加困难

接下来，数据有效性的检查应该在循环之外进行，我还要避免在循环中调用mainMenu，这会让你很快陷入一个陌生的境地。

但是，我的主要问题是

this.rainRecorded = new int[this.days];
System.out.printf("Please enter rainfall for the current day:  ");
rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
this.daysCounter++;
this.rainEntered = new int[this.daysCounter];

您不断创建this.rainRecorded 和this.rainEntered 的新实例，这意味着每次循环运行时，您都会丢失之前输入的任何内容。

因此，在我的“简化”版本中，我将其修改为...

if (this.days < 1) {
    System.out.println("Invalid number of days");
    return;
}
if (this.daysCounter == this.days) {
    System.out.printf("Error - system full\n");
    return;
}

while (this.daysCounter < this.days) {
    System.out.printf("Please enter rainfall for the day " + (daysCounter + 1) + ":  ");
    rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
    this.daysCounter++;
}

然后我也简化了直方图工作流程，但我仍在努力了解rainEntered 应该做什么......

private void displayHistogram() {
    for (int amount : rainRecorded) {
        for (int count = 0; count < amount; count++) {
            System.out.print("*");
        }
        System.out.println(" " + amount);
    }
}

我还做的最后一件事是删除所有对 mainMenu 的调用，而是依靠一个简单的 do-while 循环在每次从 Chosen 方法返回时重新打印菜单

private void mainMenu() {
    do {
        System.out.println("");
        System.out.println("*** Rain Gauge Menu ***");
        System.out.println("  1: Create rain gauge");
        System.out.println("  2: Display rain gauge details");
        System.out.println("  3: Add daily rainfall measurement");
        System.out.println("  4: Display rainfall histogram");
        System.out.println("  5: Get maximum rainfall");
        System.out.println("  6: Check rainfall is below threshold");
        System.out.println("  7: Display anaylsis");
        System.out.println("  8: Exit");
        System.out.print("Please enter your selection: ");

        Chosen();
    } while (shouldContinue);
}

这简化了工作流程，因为在程序执行的任何时候都更容易推断出你在哪里，而不是想知道为什么在某些情况下，当你从菜单中选择某些东西时，你最终会进入某个代替程序的其他部分。

示例

import java.util.Scanner;

public class RainRecording {

    private int choice;
    private Scanner input;
    private String site;
    private int days;
    private int daysCounter;
    private int[] rainRecorded;
    //private int[] rainEntered;
    private float lattitude;
    private float longitude;
    private String message1;
    private String message2;
    private String message3;
    private String message4;
    private String message5;
    private String message6;

    private boolean shouldContinue = true;

    // declare name of variable

    public RainRecording() {

        // declare value of variable

        this.message1 = "Site";
        this.message2 = "lattitude";
        this.message3 = "longitude";
        this.message4 = "Window";
        this.message5 = "days";
        this.message6 = ":";
        this.daysCounter = 0;
        this.input = new Scanner(System.in);
        mainMenu();

    }

    private void mainMenu() {
        do {
            System.out.println("");
            System.out.println("*** Rain Gauge Menu ***");
            System.out.println("  1: Create rain gauge");
            System.out.println("  2: Display rain gauge details");
            System.out.println("  3: Add daily rainfall measurement");
            System.out.println("  4: Display rainfall histogram");
            System.out.println("  5: Get maximum rainfall");
            System.out.println("  6: Check rainfall is below threshold");
            System.out.println("  7: Display anaylsis");
            System.out.println("  8: Exit");
            System.out.print("Please enter your selection: ");

            Chosen();
        } while (shouldContinue);
    }

    private void Chosen() {

        this.choice = Integer.parseInt(input.nextLine());
        switch (choice) {
            case 1:
                createGauge();
                break;

            case 2:
                gaugeDetails();
                break;
            case 3:

    if (this.days < 1) {
        System.out.println("Invalid number of days");
        return;
    }
    if (this.daysCounter == this.days) {
        System.out.printf("Error - system full\n");
        return;
    }

    while (this.daysCounter < this.days) {
        System.out.printf("Please enter rainfall for the day " + (daysCounter + 1) + ":  ");
        rainRecorded[this.daysCounter] = Integer.parseInt(input.nextLine());
        this.daysCounter++;
    }
                break;
            case 4:
                System.out.printf("\n");
                displayHistogram();
                break;
            case 5:
                break;
            case 6:
                break;
            case 7:
                break;
            case 8: shouldContinue = false;
                break;

            default:
                System.out.println("Invalid input, try again");
        }

    }



    private void createGauge() {
        System.out.printf("\nPlease enter the name of the site :");
        this.site = input.nextLine();
        System.out.printf("Please enter the number of days to record :");
        this.days = Integer.parseInt(input.nextLine());
        System.out.printf("Please enter the lattitute :");
        this.lattitude = Float.parseFloat(input.nextLine());
        System.out.printf("Please enter the longitude :");
        this.longitude = Float.parseFloat(input.nextLine());

        if (days > 0) {
            this.rainRecorded = new int[this.days];
        }
    }

    private void gaugeDetails() {

        if (this.days > 0) {

            System.out.printf("%-9s %-3s %s \n", this.message1, this.message6, this.site);
            System.out.printf("%s %-3s % 09.4f\n", this.message2, this.message6, this.lattitude);
            System.out.printf("%s %-3s %9.4f\n", this.message3, this.message6, this.longitude);
            System.out.printf("%-9s %-3s %-2d%s \n", this.message4, this.message6, this.days, this.message5);

        }

    }

    private void displayHistogram() {
        for (int amount : rainRecorded) {
            for (int count = 0; count < amount; count++) {
                System.out.print("*");
            }
            System.out.println(" " + amount);
        }
    }

    public static void main(String[] args) {
        @SuppressWarnings("unused")
        RainRecording objName;
        objName = new RainRecording();
    }
}

现在，如果rainEntered 是某种复合数组，它允许您记录不同时期的多天降雨，您可以考虑使用多维数组，这样您就可以n期间和每个期间可能有n 下雨天......