Question

我正在编写一个程序来确定乌龟，野兔，狼和绵羊之间的种族胜利者。比赛分为10个时间步（0-9）。每个参与者以不同的速度移动。我需要输出每一方的总距离并宣布获胜者，如果有平局，我可以选择任何并列方作为获胜者输出。

我的问题来自我声明数组“数组”的部分，如果确定获胜者则使用if else。我得到的错误信息是说变量“赢家”尚未初始化。我假设这是因为我没有正确比较数组条目，并且没有if语句返回true值。我的目标是将数组按升序排序，然后取最高值（行进的最远距离）并使用==运算符确定它由（野兔，乌龟，绵羊，狼）代表的变量。我做错了什么？

import java.util.*;

public class Hw3pr5 {
  public static void main(String[] args) {
    double hare = 0, tortoise = 0; //these variables will hold the total
    double sheep = 0, wolf = 0; //distance covered by each racer
    String winner;

    for (int index = 0; index < 10; index++) {
      hare = hareTimeStep(index, hare);
      tortoise = tortoiseTimeStep(index, tortoise);
      sheep = sheepTimeStep(index, sheep);
      wolf = wolfTimeStep(index, wolf);
    }

    double[] array = {
      hare, tortoise, sheep, wolf
    };
    Arrays.sort(array);
    if (array[0] == hare)
      winner = "hare";
    else if (array[0] == tortoise)
      winner = "tortoise";
    else if (array[0] == sheep)
      winner = "sheep";
    else if (array[0] == wolf)
      winner = "wolf";

    System.out.println("The race is over. The hare traveled " + hare +
      " miles.\nThe tortoise traveled " + tortoise +
      " miles.\nThe sheep traveled " + sheep + " miles.\nThe " +
      "wolf traveled " + wolf + " miles.\nThe grand winner: the " +
      winner + "!");

  }

  public static double hareTimeStep(int timestep, double distance) {
    Random rnd = new Random();
    double progress = 0;

    if (timestep < 2)
      progress = 13 + rnd.nextDouble() * 4;
    distance += progress;
    return distance;
  }

  public static double tortoiseTimeStep(int timestep, double distance) {
    Random rnd = new Random();
    double progress = 2 + rnd.nextDouble() + rnd.nextDouble();
    distance += progress;
    return distance;
  }

  public static double sheepTimeStep(int timestep, double distance) {
    Random rnd = new Random();
    double progress = 0;
    if (timestep % 2 == 0)
      progress = 6 + 4 * rnd.nextDouble();
    else
      progress -= 2;
    distance += progress;
    return distance;
  }

  public static double wolfTimeStep(int timestep, double distance) {
    Random rnd = new Random();
    double progress;

    if (timestep % 3 == 0)
      progress = 0;
    else
      progress = 4 + rnd.nextDouble();

    distance += progress;
    return distance;
  }
}

Answer 1

问题是您使用了一堆没有结尾if-else阻止的else语句。

基本上，您需要为winner提供默认值，因为在当前代码中，如果array[0]没有匹配任何内容，则永远不会设置winner。

或者，您可以在代码中添加else块，以便初始化winner。

另一种解决方案：将if-else的最后一个块更改为else。这使得最后一种情况成为默认情况。

例如：

 String winner = "default"; // this can be anything you want as long as it's not null

或

if (array[0] == hare)
  winner = "hare";
else if (array[0] == tortoise)
  winner = "tortoise";
else if (array[0] == sheep)
  winner = "sheep";
else if (array[0] == wolf)
  winner = "wolf";
else winner = "default case"

或

if (array[0] == hare)
  winner = "hare";
else if (array[0] == tortoise)
  winner = "tortoise";
else if (array[0] == sheep)
  winner = "sheep";
else winner = "wolf"; 
// the logic still works here - if it wasn't the hare, tortoise or sheep it must be the wolf

比较Java中的数组条目

1 个答案: