Java While 循环问题（新）答案

【问题标题】：Java While Loops Issue(new)Java While 循环问题（新）
【发布时间】：2016-11-09 13:38:39
【问题描述】：

我的程序有问题。
我想存储在 while 循环中看到的鸟的数量，然后在程序终止时打印最常见的鸟。
我对 if 语句有疑问。
任何帮助将不胜感激。

import java.util.*;

class gardenbird
{
    public static void main(String[] main)
    {
        askbird();
        System.exit(0);
    }// END MAIN METHOD

    public static void askbird()
    {   
        final int sentinel = -1;
        int mostseen = 0; 
        int howmany = 0;

        print("When you want to end the program type in "+sentinel);

        while(howmany != sentinel)
        {   Scanner scanner = new Scanner(System.in);
            print("Which bird have you seen?");
            String bird = scanner.nextLine();
            howmany = input("How many where in your garden at once?");

            if(howmany>mostseen)
            {
                howmany = mostseen;
            }
            print("You saw " + howmany+ " " + bird +"\n It was the most common bird in your garden.");
        }
    }

    public static String print(String message)
    {       
        System.out.println(message);
        return message;
    }

    public static int input(String count)
    {   
        Scanner scanner = new Scanner(System.in);
        print(count);
        String number1=scanner.nextLine();

        int number = Integer.parseInt(number1);
        return number;
    }
}

【问题讨论】：

howmany = mostseen 应该是 mostseen = howmany。
您也可以重新考虑过度使用新的 Scanner 实例。

标签： java if-statement methods while-loop procedural-programming

【解决方案1】：

你的 if 语句的内容是向后的，试试这个：

if(howmany > mostseen)
{
   mostseen = howmany;
}

还有，

print("You saw " + mostseen + " " + bird +"\n It was the most common bird in your garden.");

可能应该在一段时间之外？这样，您只会在终止时通知用户，而不是每次他们输入新条目时。您并没有真正的设计可以让您跳出循环，但这就是您的问题所述...或者，您可以将其放在 if 语句中，以便仅在条件为真时打印出来

【讨论】：

【解决方案2】：

正如其他人指出的那样，您的 if 块替换是倒退的。

创建一个实用方法来执行 System.out.println() 是过度封装。

一遍又一遍地创建对象会浪费系统资源并降低代码的可读性，但是您走在正确的轨道上。

比较和对比这个。

import java.util.Scanner;

public class GardenBird
{
  public static void main(String[] main)
  {
    askbird();
    System.exit(0);
  }// END MAIN METHOD

  public static void askbird()
  {
    Scanner scanner = new Scanner(System.in);
    final int sentinel = -1;
    int mostseen = 0;
    int howmany = 0;
    String mostSeenBird = "";
    String currentBird = "";

    System.out.println("When you want to end the program type in " + sentinel);

    while (howmany != sentinel)
    {
      System.out.println("Which bird have you seen?");
      currentBird = scanner.nextLine();
      System.out.println("How many where in your garden at once?");
      howmany = Integer.parseInt(scanner.nextLine());

      if (howmany > mostseen)
      {
        mostseen = howmany;
        mostSeenBird = currentBird;
      }
    }
    System.out.println("You saw " + howmany + " " + mostSeenBird
        + "\n It was the most common bird in your garden.");
    scanner.close();
  }
}

【讨论】：