Java 形成这个if语句的更好方法是什么？

我目前正在从一本书中学习java，一个项目是在输入月数后输出一个月的天数和月名。我想知道是否有比我已经做的更好的方法来设置我的if语句

PS:ConsoleReader只是一个包含的类，可以轻松地从用户控制台获取输入

public class Project13 {

public static void main(String[] args) {
    ConsoleReader console = new ConsoleReader(System.in);

    System.out.println("Enter a month you would like to evaluate (by number):");
    int month = console.readInt();

    int days = 0;
    String monthout = "Month";
    String out = "Yes";
    if(month == 1){
        days = 31;
        monthout = "January";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 2){
        System.out.println("Is it a leap year? Yes or No:");
        String leap = console.readLine(); 
        if(leap.equalsIgnoreCase("yes")){
            days = 29;
            monthout = "February";
            out = "There are " + days + " days in " + monthout;
        }else if(leap.equalsIgnoreCase("no")){
            days = 28;
            monthout = "February";
            out = "There are " + days + " days in " + monthout;
        }else{
            out = "Something went wrong, please try again";
        }
    }else if(month == 3){
        days = 31;
        monthout = "March";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 4){
        days = 30;
        monthout= "April";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 5){
        days = 31;
        monthout = "May";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 6){
        days = 30;
        monthout = "June";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 7){
        days = 31;
        monthout = "July";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 8){
        days = 31;
        monthout = "August";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 9){
        days = 30;
        monthout = "September";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 10){
        days = 31;
        monthout = "October";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 11){
        days = 30;
        monthout = "November";
        out = "There are " + days + " days in " + monthout;
    }else if(month == 12){
        days = 31;
        monthout = "December";
        out = "There are " + days + " days in " + monthout;
    }else if(month > 12){
        out = "Your month input was not valid. Please try again.";
    }

    System.out.println(out);
}

}

如果你要这样做，你肯定应该使用

enum

，而不仅仅是表示月份的整数

---

如果你要这样做，你一定要使用

枚举

，而不仅仅是表示月份的整数…

你可以使用

开关大小写

语句。避免使用太多if-else语句

switch(month) {
    case 1:
        days = 31;
        monthout = "January";
        out = "There are " + days + " days in " + monthout;
        break;
    case 2:
        // Add stuff
         break;
    default:
        break;
}

---

你可以使用

开关盒
语句。如果没有其他语句，请避免使用太多

switch(month) {
    case 1:
        days = 31;
        monthout = "January";
        out = "There are " + days + " days in " + monthout;
        break;
    case 2:
        // Add stuff
         break;
    default:
        break;
}

Swtich：

switch (month)
{
    case 1:
        // ... stuff here
        break;
    case 2:
        // ... stuff here
        break;
    // ... more cases
    default: // no case above matched what the month was
        // .... handle default case
};

Swtich：

switch (month)
{
    case 1:
        // ... stuff here
        break;
    case 2:
        // ... stuff here
        break;
    // ... more cases
    default: // no case above matched what the month was
        // .... handle default case
};

如果需要，请使用switch语句而不是其他许多语句。它更容易阅读，修改和休息的工作速度比其他如果

case 1:
//code
break; 

如果需要，请使用switch语句而不是其他许多语句。它更容易阅读，修改和休息的工作速度比其他如果

case 1:
//code
break; 

您可以用一对数组替换几乎整个
if
语句，如下所示：

int dayCount[] = new int[] {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
String monthName[] = new String[] {"January", "February", ...};

有了这两个阵列，您可以执行以下操作：

// February is the only month that needs special handling
if (month == 2) {
    // Do your special handling of leap year etc...
} else if (month >= 1 && month <= 12) {
    // All other valid months go here. Since Java arrays are zero-based,
    // we subtract 1 from the month number
    days = dayCount[month-1];
    monthout = monthName[month-1];
} else {
    // Put handling of invalid month here
}
out = "There are " + days + " days in " + monthout;

//二月是唯一需要特殊处理的月份
如果（月份==2）{
//你对闰年等的特殊处理。。。
}else if（month>=1&&month您可以用一对数组替换几乎整个
if
语句，如下所示：

int dayCount[] = new int[] {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
String monthName[] = new String[] {"January", "February", ...};

有了这两个阵列，您可以执行以下操作：

// February is the only month that needs special handling
if (month == 2) {
    // Do your special handling of leap year etc...
} else if (month >= 1 && month <= 12) {
    // All other valid months go here. Since Java arrays are zero-based,
    // we subtract 1 from the month number
    days = dayCount[month-1];
    monthout = monthName[month-1];
} else {
    // Put handling of invalid month here
}
out = "There are " + days + " days in " + monthout;

//二月是唯一需要特殊处理的月份
如果（月份==2）{
//你对闰年等的特殊处理。。。
}else if（month>=1&&month我认为您应该使用
Map
来避免所有这些if（或switch）情况。代码的主要问题是您的代码重复了很多代码

private static Map<Integer, Integer> monthDays = new HashMap<>();

static {
    monthDays.put(1, 31);
    monthDays.put(2, 28);
    ...
}

private static int getMonthDays(int month) {
    if (month == 2) {
        // handle special case with Februar
    }
    return monthDays.get(month);
}

public static void main(String[] args) {
   ...    
   if (month >= 1 && month <= 12) {
       monthout = getMonthDays(month);
       ...
       out = "There are " + days + " days in " + monthout;
   } else {
       out = "Your month input was not valid. Please try again.";
   }
   System.out.println(out);
}

private static Map monthDays=new HashMap（）；
静止的{
月日.投入产出（1,31）；
月日。投入产出（2,28）；
...
}
私有静态整数getMonthDays（整数月）{
如果（月份==2）{
//2月处理特殊情况
}
返回monthDays.get（月）；
}
公共静态void main（字符串[]args）{
...    
if（month>=1&&month我认为您应该使用
Map
来避免所有这些if（或switch）情况。代码的主要问题是您的代码重复了很多代码

private static Map<Integer, Integer> monthDays = new HashMap<>();

static {
    monthDays.put(1, 31);
    monthDays.put(2, 28);
    ...
}

private static int getMonthDays(int month) {
    if (month == 2) {
        // handle special case with Februar
    }
    return monthDays.get(month);
}

public static void main(String[] args) {
   ...    
   if (month >= 1 && month <= 12) {
       monthout = getMonthDays(month);
       ...
       out = "There are " + days + " days in " + monthout;
   } else {
       out = "Your month input was not valid. Please try again.";
   }
   System.out.println(out);
}

private static Map monthDays=new HashMap（）；
静止的{
月日.投入产出（1,31）；
月日。投入产出（2,28）；
...
}
私有静态整数getMonthDays（整数月）{
如果（月份==2）{
//2月处理特殊情况
}
返回monthDays.get（月）；
}
公共静态void main（字符串[]args）{
...    
if（month>=1&&month切换情况也不好。如果超过3-4 if else或切换条件，请考虑其他方式，如命令或策略模式或其他方式

例如，创建一个动作图，在if条件下设置并执行您想要的动作。示例代码如下。这只是示例代码，如果您需要对任何部分进行进一步细化，请告知我：

public void initMap(){
         Map<Integer, MonthData> monthDataMap = new HashMap<Integer,MonthData>();
         monthDataMap.put(1,new JanData());
         monthDataMap.put(2,new FebData());

     }

    interface MonthData {
        public String getMonth();
        public int getDays();
        public String getOut();
    }

    class JanData  implements MonthData{
        private String month ="January";
        private int days = 30;
        private String out =  "There are " + days + " days in " + month;

        @Override
        public String getMonth() {
            return month;
        }

        @Override
        public int getDays() {
            return days;
        }

        @Override
        public String getOut() {
            return out;
        }
    }


    class FebData {
        private String month ="February";
        private int days = 28;
        private String out =  "There are " + days + " days in " + month;
    }

    ....

public void initMap（）{
Map monthDataMap=新HashMap（）；
monthDataMap.put（1，new JanData（））；
monthDataMap.put（2，新的FebData（））；
}
接口MonthData{
公共字符串getMonth（）；
public int getDays（）；
公共字符串getOut（）；
}
类JanData实现MonthData{
私有字符串month=“一月”；
私人整数天=30天；
private String out=“在“+月份中有“+天+”天；
@凌驾
公共字符串getMonth（）{
返回月份；
}
@凌驾
公共整数getDays（）{
返程天数；
}
@凌驾
公共字符串getOut（）{
返回；
}
}
类FebData{
私有字符串month=“二月”；
私人整数天=28天；
private String out=“在“+月份中有“+天+”天；
}
....
切换情况也不好。如果有超过3-4个If else或切换条件，请考虑其他方式，如命令或策略模式或其他方式

例如，创建一个动作图，在if条件下设置并执行您想要的动作。示例代码如下。这只是示例代码，如果您需要对任何部分进行进一步细化，请告知我：

public void initMap(){
         Map<Integer, MonthData> monthDataMap = new HashMap<Integer,MonthData>();
         monthDataMap.put(1,new JanData());
         monthDataMap.put(2,new FebData());

     }

    interface MonthData {
        public String getMonth();
        public int getDays();
        public String getOut();
    }

    class JanData  implements MonthData{
        private String month ="January";
        private int days = 30;
        private String out =  "There are " + days + " days in " + month;

        @Override
        public String getMonth() {
            return month;
        }

        @Override
        public int getDays() {
            return days;
        }

        @Override
        public String getOut() {
            return out;
        }
    }


    class FebData {
        private String month ="February";
        private int days = 28;
        private String out =  "There are " + days + " days in " + month;
    }

    ....

public void initMap（）{
Map monthDataMap=新HashMap（）；
monthDataMap.put（1，new JanData（））；
monthDataMap.put（2，新的FebData（））；
}
接口MonthData{
公共字符串getMonth（）；
public int getDays（）；
公共字符串getOut（）；
}
类JanData实现MonthData{
私有字符串month=“一月”；
私人整数天=30天；
private String out=“在“+月份中有“+天+”天；
@凌驾
公共字符串getMonth（）{
返回月份；
}
@凌驾
公共整数getDays（）{
返程天数；
}
@凌驾
公共字符串getOut（）{
返回；
}
}
类FebData{
私有字符串month=“二月”；
私人整数天=28天；
private String out=“在“+月份中有“+天+”天；
}
....
不一定更好，但您可以尝试
切换case
语句：不一定更好，但您可以尝试
切换case
语句：+1。这是唯一的答案，它不仅用过程切换语句的集合替换过程if语句的集合，而且使用合理的编程pr这是唯一的答案，它不仅用一组过程切换语句代替了一组过程if语句，而且使用了合理的编程原则。