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if-else if语句中如何进行两个运算？

[英]How can two operations be in if-else if statement?

 原文  2013-11-03 10:01:55  5   5    java/ if-statement

问题描述

我正在尝试制作一个简单的足球模拟程序，但是在团队之间进行配对时遇到了问题。 如果找到一个条件，则if语句退出循环。 但是我想做两个条件和两个操作。 可能吗？ 

package soccer.simulator;
import java.util.Random;
/**
 * @author Sertac
 */
public class SoccerSimulator {
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        int HomeTeamScore = 0;
        int AwayTeamScore = 0;
        Random randomGenerator = new Random();

        String HomeTeam = new String();
        String AwayTeam = new String();
        int HomeTeamID = randomGenerator.nextInt(10);
        int AwayTeamID = randomGenerator.nextInt(10);

        if(HomeTeamID == AwayTeamID){
            while (HomeTeamID != AwayTeamID){
                AwayTeamID = randomGenerator.nextInt(10);
            }
        }

        if(HomeTeamID == 0 || AwayTeamID == 0){
            if(HomeTeamID == 0){
                HomeTeam = "Arsenal";
            }else{
                AwayTeam = "Arsenal";
            }
        } else if(HomeTeamID == 1 || AwayTeamID == 1){
            if(HomeTeamID == 1){
                HomeTeam = "Barcelona";
            }else{
                AwayTeam = "Barcelona";
            }
        } else if(HomeTeamID == 2 || AwayTeamID == 2){
            if(HomeTeamID == 2){
                HomeTeam = "Bayern Munich";
            }else{
                AwayTeam = "Bayern Munich";
            }
        } else if(HomeTeamID == 3 || AwayTeamID == 3){
            if(HomeTeamID == 3){
                HomeTeam = "Chelsea";
            }else{
                AwayTeam = "Chelsea";
            }
        } else if(HomeTeamID == 4 || AwayTeamID == 4){
            if(HomeTeamID == 4){
                HomeTeam = "Borussia Dortmund";
            }else{
                AwayTeam = "Borussia Dortmund";
            }
        } else if(HomeTeamID == 5 || AwayTeamID == 5){
            if(HomeTeamID == 5){
                HomeTeam = "Galatasaray";
            }else{
                AwayTeam = "Galatasaray";
            }
        } else if(HomeTeamID == 6 || AwayTeamID == 6){
            if(HomeTeamID == 6){
                HomeTeam = "Juventus";
            }else{
                AwayTeam = "Juventus";
            }
        } else if(HomeTeamID == 7 || AwayTeamID == 7){
            if(HomeTeamID == 7){
                HomeTeam = "Manchester United";
            }else{
                AwayTeam = "Manchester United";
            }
        } else if(HomeTeamID == 8 || AwayTeamID == 8){
            if(HomeTeamID == 8){
                HomeTeam = "Milan";
            }else{
                AwayTeam = "Milan";
            }
        } else if(HomeTeamID == 9 || AwayTeamID == 9){
            if(HomeTeamID == 9){
                HomeTeam = "Real Madrid";
            }else{
                AwayTeam = "Real Madrid";
            }
        }

        //Generating each random integers in range 0..99 for 90 minutes
        for(int minutes = 0; minutes <= 90; minutes++){
            int randomInt = randomGenerator.nextInt(100);

            //if random int equals 0,1,2 home team scores
            if(randomInt < 3){ HomeTeamScore = HomeTeamScore + 1; }

            //if random int equals 98,99 away team scores
            //home team has 1 more int because playing at home is better
            if(randomInt > 97){ AwayTeamScore = AwayTeamScore + 1; }                         
        }
        System.out.println ("Simulation for match of the week:");
        System.out.println (HomeTeam + " " + HomeTeamScore + " - " + AwayTeamScore + " " + AwayTeam);

        }   
    }

输出为： 3 - 1 Arsenal

或： Arsenal 2 - 1

5 个解决方案

解决方案1
 5 已采纳  2013-11-03 10:13:44

您只设置一个团队名称是因为根本没有循环，在您庞大的if-else语句中只有一个最终条件是正确的。 一种更简单的方法（强烈建议使用此方法，以使在不久的将来会碰到您代码的其他人保持理智）将您的团队名称存储在一个数组中。 

String[] teamNames = new String[] {"Arsenal", "Barcelona", "Bayern Munich", "Chelsea", "Borussia Dortmund", "Galatasaray", "Juventus", "Manchester United", "Milan", "Real Madrid"};

然后替换整个if-else 。 

HomeTeam = teamNames[HomeTeamID];
AwayTeam = teamNames[AwayTeamID];

附带说明一下，您应遵循Java约定进行变量命名，并使用小写的camelCase（ homeTeam ， awayTeam ， homeTeamID ， awayTeamId ）。

解决方案2
 2  2013-11-03 10:14:48

改变else if if

尝试 

import java.util.Random;
/**
 * @author Sertac
 */
public class SoccerSimulator {
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        int HomeTeamScore = 0;
        int AwayTeamScore = 0;
        Random randomGenerator = new Random();

        String HomeTeam = new String();
        String AwayTeam = new String();
        int HomeTeamID = randomGenerator.nextInt(10);
        int AwayTeamID = randomGenerator.nextInt(10);

        if(HomeTeamID == AwayTeamID){
            while (HomeTeamID != AwayTeamID){
                AwayTeamID = randomGenerator.nextInt(10);
            }
        }

        if(HomeTeamID == 0 || AwayTeamID == 0){
            if(HomeTeamID == 0){
                HomeTeam = "Arsenal";
            }else{
                AwayTeam = "Arsenal";
            }
        }  if(HomeTeamID == 1 || AwayTeamID == 1){
            if(HomeTeamID == 1){
                HomeTeam = "Barcelona";
            }else{
                AwayTeam = "Barcelona";
            }
        }  if(HomeTeamID == 2 || AwayTeamID == 2){
            if(HomeTeamID == 2){
                HomeTeam = "Bayern Munich";
            }else{
                AwayTeam = "Bayern Munich";
            }
        }  if(HomeTeamID == 3 || AwayTeamID == 3){
            if(HomeTeamID == 3){
                HomeTeam = "Chelsea";
            }else{
                AwayTeam = "Chelsea";
            }
        }  if(HomeTeamID == 4 || AwayTeamID == 4){
            if(HomeTeamID == 4){
                HomeTeam = "Borussia Dortmund";
            }else{
                AwayTeam = "Borussia Dortmund";
            }
        }  if(HomeTeamID == 5 || AwayTeamID == 5){
            if(HomeTeamID == 5){
                HomeTeam = "Galatasaray";
            }else{
                AwayTeam = "Galatasaray";
            }
        }  if(HomeTeamID == 6 || AwayTeamID == 6){
            if(HomeTeamID == 6){
                HomeTeam = "Juventus";
            }else{
                AwayTeam = "Juventus";
            }
        }  if(HomeTeamID == 7 || AwayTeamID == 7){
            if(HomeTeamID == 7){
                HomeTeam = "Manchester United";
            }else{
                AwayTeam = "Manchester United";
            }
        }  if(HomeTeamID == 8 || AwayTeamID == 8){
            if(HomeTeamID == 8){
                HomeTeam = "Milan";
            }else{
                AwayTeam = "Milan";
            }
        }  if(HomeTeamID == 9 || AwayTeamID == 9){
            if(HomeTeamID == 9){
                HomeTeam = "Real Madrid";
            }else{
                AwayTeam = "Real Madrid";
            }
        }

        //Generating each random integers in range 0..99 for 90 minutes
        for(int minutes = 0; minutes <= 90; minutes++){
            int randomInt = randomGenerator.nextInt(100);

            //if random int equals 0,1,2 home team scores
            if(randomInt < 3){ HomeTeamScore = HomeTeamScore + 1; }

            //if random int equals 98,99 away team scores
            //home team has 1 more int because playing at home is better
            if(randomInt > 97){ AwayTeamScore = AwayTeamScore + 1; }                         
        }
        System.out.println ("Simulation for match of the week:");
        System.out.println (HomeTeam + " " + HomeTeamScore + " - " + AwayTeamScore + " " + AwayTeam);

        }   
    }

解决方案3
 0  2013-11-03 10:13:59

问题出在这里： 

if(HomeTeamID == 0 || AwayTeamID == 0){
            if(HomeTeamID == 0){
                HomeTeam = "Arsenal";
            }else{
                AwayTeam = "Arsenal";
            }
        } else if(HomeTeamID == 1 || AwayTeamID == 1){
            if(HomeTeamID == 1){
                HomeTeam = "Barcelona";
            }else{
                AwayTeam = "Barcelona";
            }
        } else if(HomeTeamID == 2 || AwayTeamID == 2){
            if(HomeTeamID == 2){
                HomeTeam = "Bayern Munich";
            }else{
                AwayTeam = "Bayern Munich";
            }
        } else if(HomeTeamID == 3 || AwayTeamID == 3){
            if(HomeTeamID == 3){
                HomeTeam = "Chelsea";
            }else{
                AwayTeam = "Chelsea";
            }
        } else if(HomeTeamID == 4 || AwayTeamID == 4){
            if(HomeTeamID == 4){
                HomeTeam = "Borussia Dortmund";
            }else{
                AwayTeam = "Borussia Dortmund";
            }
        } else if(HomeTeamID == 5 || AwayTeamID == 5){
            if(HomeTeamID == 5){
                HomeTeam = "Galatasaray";
            }else{
                AwayTeam = "Galatasaray";
            }
        } else if(HomeTeamID == 6 || AwayTeamID == 6){
            if(HomeTeamID == 6){
                HomeTeam = "Juventus";
            }else{
                AwayTeam = "Juventus";
            }
        } else if(HomeTeamID == 7 || AwayTeamID == 7){
            if(HomeTeamID == 7){
                HomeTeam = "Manchester United";
            }else{
                AwayTeam = "Manchester United";
            }
        } else if(HomeTeamID == 8 || AwayTeamID == 8){
            if(HomeTeamID == 8){
                HomeTeam = "Milan";
            }else{
                AwayTeam = "Milan";
            }
        } else if(HomeTeamID == 9 || AwayTeamID == 9){
            if(HomeTeamID == 9){
                HomeTeam = "Real Madrid";
            }else{
                AwayTeam = "Real Madrid";
            }
        }

U始终只分配一个队，无论是主队还是客队，因为您在这里使用的结构错误。 尝试类似的方法： 

switch(HomeTeamID)
{
case 0: HomeTeam = "Arsenal";
        break;
case 1: HomeTeam = "Barcelona";
...
break
}

与客队相同： 

switch(HomeTeamID)
{
case 0: AwayTeam = "Arsenal";
        break;
case 1: AwayTeam = "Barcelona";
...
break
}

并且您应该检查Java代码约定。.变量名应以小写字母开头。

解决方案4
 0  2013-11-03 10:16:02

如果用if替换else，则代码应该可以正常工作。

解决方案5
 0  2013-11-03 10:28:21

我将从一开始就开始。 您正在尝试做什么。

给定一些团队，您想选择两个随机的团队互相比赛，一个主场一个。

当前，您正在从“ Random中选择两个随机int id，并使用它们在隐含的团队数组中查找团队。

因此，首先使用@ssantos的建议-使数组明确，然后从那里简单地获取索引。

但是，我们有一个问题-团队无法发挥自己的作用。 因此，实际上我们需要一种略有不同的方法。 您需要做的是将所有团队组成的数组，将其洗牌，然后从数组中读取对。 实际上，这就是选择倾向于在锦标赛中起作用的方式。

这是我建议的代码： 

private static final String[] TEAM_NAMES = new String[]{"Arsenal", "Barcelona", "Bayern Munich", "Chelsea", "Borussia Dortmund", "Galatasaray", "Juventus", "Manchester United", "Milan", "Real Madrid"};
private static final Random RANDOM = new Random();

public static void main(final String args[]) {
    List<String> teams = new ArrayList<>(Arrays.asList(TEAM_NAMES));
    while (teams.size() > 1) {
        teams = playRound(teams);
    }
    System.out.println("The champion is " + teams);
}

public static List<String> playRound(final List<String> teams) {
    Collections.shuffle(teams);
    final Iterator<String> teamsIter = teams.iterator();
    final List<String> winners = new ArrayList<>();
    while (teamsIter.hasNext()) {
        final String winner = play(teamsIter.next(), teamsIter.next());
        winners.add(winner);
    }
    return winners;
}

public static String play(final String team1, final String team2) {
    return RANDOM.nextBoolean() ? team1 : team2;
}

从顶部：

首先，我们声明常量-团队数组和Random实例。 这些变量是static final变量，因此在BLOCK_CAPITALS中命名。

主要

接下来，我们得出main方法。 此方法将团队带入List 。 我们需要复制团队，以免弄乱团队数组。 List是一种更灵活的结构，您将在后面看到。 还要注意，您需要两支球队的力量-如果两队成对比赛，那么您需要在每一回合中将数字除以2。

该方法现在进入while循环。 这种结构可以让每一轮的所有获胜球队互相对抗，直到获得最终冠军-锦标赛冠军。 它打印出冠军的名字。

playRound

这就是魔术发生的地方。

该方法首先对进入的团队进行shuffles以便随机检索它们。 然后，它获取List的Iterator -这使您可以逐元素遍历List元素。 如果没有偶数的团队，这也是引发错误的地方-第二个next()将引发NoSuchElementException 。

然后，该方法进入另一个while循环-而Iterator不为空，它调用play两支球队。 它将获胜团队放入winners List 。 这是最后返回的List 。

List不是具有add方法，因此您可以动态填充它-这与具有固定大小的数组不同。

玩

这就是您实际的模拟的去向。 目前，它随机选择一个获胜者-您可以输入当前的方法。

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