Java Assignment（在if语句中更改字符串值）

时间：2012-02-23 08:36:25

标签： java string if-statement

这是分配。我相信我只能使用If和else语句

  

以下算法产生季节（春季，夏季，秋季或夏季）   冬天）一天中的某个月。

IF month is 1,2, or 3, season = "Winter
Else if month is 4, 5, or 6, season = "Spring"
Else if month is 7,8, 9, season = "Summer"
Else if month is 10,11, or 12, season = "Fall"
If month is divisible by 3 and day >= 21
     If season is "Winter", season = "Spring"
     Else if season is "Spring", season = "Summer"
     Else if season is "Summer", season = "Fall"
     Else season = "Winter"
     

编写一个程序，提示用户一个月和一天然后   打印季节，由此算法确定

到目前为止我得到了什么。如果月份可以被3整除并且日期高于20，我无法得到最后一部分来改变季节。

import java.util.Scanner;

public class Seasons {

    public static void main (String[] args){

        Scanner in = new Scanner(System.in);
        int month;
        int day;
        String season = null;

        System.out.print("Please enter month and day: ");
        month = in.nextInt();
        day = in.nextInt();

        if(1 <= month && month <=3){
            season = "Winter";
            System.out.println(season);
        }

        else if (4 <= month && month <=6){
            season = "Spring";
            System.out.println(season);
        }

        else if (7 <=month && month <=9){
            season = "Summer";
            System.out.println(season);
        }

        else if (10 <= month && month <= 12){
            season = "Fall";
            System.out.println(season);
        }


        if ( ((month % 3 == 0) && (21 <= day)){
            if (season.equals("Winter")){

            }

            else if (season.equals("Spring")){
                season = ("Summer");
            }

            else if (season.equals("Summer")){
                season = "Fall";
            }

            else {
                season = "Winter";
            }


        }
    }
}

7 个答案:

答案 0 :(得分：2)

根据您的条件，这样的事情应该有效：

private String getSesson(int month, int day) {
    String season = "";
    switch (month) {
        case 1:
        case 2:
        case 3:
            season = "Winter";
            if(month % 3 == 0 && day >=21)
                season = "Spring";
            break;
        case 4:
        case 5:
        case 6:
            season = "Spring";
            if(month % 3 == 0 && day >=21)
                season = "Summer";
            break;
        case 7:
        case 8:
        case 9:
            season = "Summer";
            if(month % 3 == 0 && day >=21)
                season = "Fall";
            break;
        case 10:
        case 11:
        case 12:
            season = "Fall";
            if(month % 3 == 0 && day >=21)
                season = "Winter";
            break;
        default:
            season = "Not a valid month";
            break;  
    }
    return season;
}

试验：

    System.out.println(getSesson(1, 0));
    System.out.println(getSesson(2, 0));
    System.out.println(getSesson(3, 0));
    System.out.println(getSesson(3, 21));
    System.out.println(getSesson(4, 0));
    System.out.println(getSesson(5, 0));
    System.out.println(getSesson(6, 0));
    System.out.println(getSesson(6, 21));
    System.out.println(getSesson(7, 0));
    System.out.println(getSesson(8, 0));
    System.out.println(getSesson(9, 0));
    System.out.println(getSesson(9, 21));
    System.out.println(getSesson(10, 0));
    System.out.println(getSesson(11, 0));
    System.out.println(getSesson(12, 0));
    System.out.println(getSesson(12, 21));

以上Syso打印：

Winter
Winter
Winter
Spring
Spring
Spring
Spring
Summer
Summer
Summer
Summer
Fall
Fall
Fall
Fall
Winter

如果...版本：

    Scanner in = new Scanner(System.in);
    int month, day; String season = null;
    System.out.print("Please enter month and day: ");
    month = in.nextInt(); day = in.nextInt();
    if(1 <= month && month <= 3){
        season = "Winter";
        if((month == 3) && (21 <= day))
            season = "Spring";
    } else if (4 <= month && month <=6){
        season = "Spring";
        if((month == 6) && (21 <= day))
            season = "Summer";
    } else if (7 <=month && month <=9){
        season = "Summer";
        if((month == 9) && (21 <= day))
            season = "Fall";
    } else if (10 <= month && month <= 12){
        season = "Fall";
        if((month == 12) && (21 <= day))
            season = "Winter";
    }
    System.out.println(season);

答案 1 :(得分：1)

为了您自己的兴趣，您可以使用

String season= "Winter,Spring,Summer,Fall".split(",")[(month + day/21 - 1)/3 &3];

for (int month = 1; month <= 12; month++)
    for (int day = 20; day <= 21; day++) {
        String season = "Winter,Spring,Summer,Fall".split(",")[(month + day / 21 - 1) / 3 & 3];
        System.out.println(day + "/" + month + " => " + season);
    }

打印

20/1 => Winter
21/1 => Winter
20/2 => Winter
21/2 => Winter
20/3 => Winter
21/3 => Spring
20/4 => Spring
21/4 => Spring
20/5 => Spring
21/5 => Spring
20/6 => Spring
21/6 => Summer
20/7 => Summer
21/7 => Summer
20/8 => Summer
21/8 => Summer
20/9 => Summer
21/9 => Fall
20/10 => Fall
21/10 => Fall
20/11 => Fall
21/11 => Fall
20/12 => Fall
21/12 => Winter

答案 2 :(得分：0)

使用模数运算符（％）来获取除法后的提醒，如下所示：

if ((month % 3) == 0 && day >= 21)
{
  if (season.equals("Winter")) 
  { 
    season = "Summer";
  }
  // ... etc ...
}

答案 3 :(得分：0)

我认为这是来自if块中的逻辑测试，使用括号作为一个单元进行测试：

if ( ((month % 3) == 0) && (day >= 21) )

修改：

您需要做的就是将变量重新分配给新赛季。

if ( ((month % 3) == 0) && (day >= 21) ) {
    season = "Winter";
}

继续在season

中打印

只要条件全部评估为true。然后变量将更改为winter。但如果它是false则不会改变。

您可以尝试：

if(true) {
   season = "Winter";
}

System.out.println(season);

您应该看到Winter。

答案 4 :(得分：0)

您的原始算法看起来不对.. 如果你在第一部分确定它是冬天（第1,2或3个月）并且它是第3个月并且那天大于20，那将是春天，而不是夏天..

这是应该说的：

if (month % 3 == 0 && 21 <= day){
    if (season.equals("Winter")){
        season = "Spring"
    }

    else if (season.equals("Spring")){
        season = "Summer";
    }

    else if (season.equals("Summer")){
        season = "Fall";
    }

    else {
        season = "Winter";
    }
}

你错过了冬天的价值。

或者你可以这样做：

public class Seasons {

  public static void main (String[] args){

    Scanner in = new Scanner(System.in);
    int month;
    int day;
    String season = null;

    System.out.print("Please enter month and day: ");
    month = in.nextInt();
    day = in.nextInt();
    String[] seasons = {"Winter", "Spring", "Summer", "Fall"};
    if (day >= 21 && month % 3 == 0) {
            season = seasons[((month + 2) / 3) % 4];
    } else {
            season = seasons[((month-1)/3)];
    }
    System.out.println("Season: " + season);
  }
}

答案 5 :(得分：0)

代码上的实际问题（一般来说，有效）是您在更改之前打印季节值。这就是为什么你无法看到算法的第二部分何时起作用的原因。

删除每个if语句的System.out，并在方法结束时仅更改它们。还要修复你的最后一个if / elses，因为冬天是空的。 最终代码：

public static void main (String[] args){

    Scanner in = new Scanner(System.in);
    int month;
    int day;
    String season = null;

    System.out.print("Please enter month and day: ");
    month = in.nextInt();
    day = in.nextInt();

    if(1 <= month && month <=3){
        season = "Winter";
    }

    else if (4 <= month && month <=6){
        season = "Spring";
    }

    else if (7 <=month && month <=9){
        season = "Summer";
    }

    else if (10 <= month && month <= 12){
        season = "Fall";
    }


    if ( ((month % 3 == 0) && (21 <= day)){
        if (season.equals("Winter")){
            season="Spring";
        }

        else if (season.equals("Spring")){
            season = "Summer";
        }

        else if (season.equals("Summer")){
            season = "Fall";
        }

        else {
            season = "Winter";
        }


    }

    System.out.println(season);
}

这将打印最终结果（即3月22日的“春天”）。

答案 6 :(得分：0)

import javax.swing.JOptionPane;

public class SeasonDetictor {

    public static void main(String[] args) {
         // TODO Auto-generated method stub
         String month1 = JOptionPane.showInputDialog("please enter number of the month");
         String day1 = JOptionPane.showInputDialog("please enter number of the day");
         int month = Integer.parseInt(month1);
         int day = Integer.parseInt(day1);

         if ((month == 3)&&(day >= 21 && day <= 31) ) {    
             JOptionPane.showMessageDialog(null, "spring"); 
         }

         else if ((month == 4)||(month == 5)) {
             JOptionPane.showMessageDialog(null, "spring"); 
         }

         else if  ((month == 6) && (day < 21)) {
             JOptionPane.showMessageDialog(null, "spring"); 
         }

         if ((month == 6)&&(day >= 21 && day <= 31) ) {    
             JOptionPane.showMessageDialog(null, "summer"); 
         }

         else if ((month == 7)||(month == 8)) {
             JOptionPane.showMessageDialog(null, "summer"); 
         }

         else if  ((month == 9) && (day < 21)) {
             JOptionPane.showMessageDialog(null, "summer"); 
         }

         if ((month == 9)&&(day >= 21 && day <= 31) ) {    
             JOptionPane.showMessageDialog(null, "fall"); 
         }

         else if ((month == 10)||(month == 11)) {
             JOptionPane.showMessageDialog(null, "fall"); 
         }

         else if  ((month == 12) && (day < 21)) {
             JOptionPane.showMessageDialog(null, "fall"); 
         }


         if ((month == 12)&&(day >= 21 && day <= 31) ) {    
             JOptionPane.showMessageDialog(null, "winter"); 
         }

         else if ((month == 1)||(month == 2)) {
             JOptionPane.showMessageDialog(null, "winter"); 
         }

         else if  ((month == 3) && (day < 21)) {
             JOptionPane.showMessageDialog(null, "winter"); 
         }

    }
}
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