我需要使用for循环多次执行println（）

-5

我需要帮助编写一个for循环，它将根据用户输入的“sides”变量多次打印语句。我的while循环似乎也有问题，请让我知道我的语法是否关闭。我需要使用for循环多次执行println（）

import java.util.Scanner; 
public class Lab6 { 
public static void main(String[] args) { 

     Scanner scan = new Scanner(System.in); 
     int sides = 0; 
     String poly = "ERROR!!!!!!"; 

     System.out.print("Enter a number from 3 to 12: "); 
     sides = scan.nextInt(); 

     while (sides > 3 || < 12){ 
      System.out.println("Please enter a number from 3 to 12: ") 
     } 


     if(sides == 3) { 
      poly = "Triangle"; 
     } else if(sides == 4) { 
      poly = "Quadrilaterl"; 
     } else if(sides == 5) { 
      poly = "Pentagon"; 
     } else if(sides == 6) { 
      poly = "Hexagon"; 
     } else if(sides == 7) { 
      poly = "Heptagon"; 
     } else if(sides == 8) { 
      poly = "Octagon"; 
     } else if(sides == 9) { 
      poly = "Nonagon"; 
     } else if(sides == 10) { 
      poly = "Decagon"; 
     } else if(sides == 12) { 
      poly = "Dodecagon"; 
     } 

      for (sides >= 3 || <= 12){ 
       System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides, poly);//TODO:Use a 'for loop' here! 
     } 


}

来源

2013-05-02 amwindso

*“我需要帮助” *什么帮助，特别？请注意，SO不是“修复/完成我的代码”服务。除非你问一个具体的问题（最好只是***一个问题），否则这可能会被关闭。 – 2013-05-02 13:54:12

我很抱歉，正如我下面所说的，我是新来的SO，并且认为只要求完整的答案就会被忽视。 – amwindso 2013-05-02 14:21:59

首先，你需要改变

while (sides > 3 || < 12){ 
     System.out.println("Please enter a number from 3 to 12: ") 
    }

到

while (sides < 3 || sides > 12) { 
     System.out.println("Please enter a number from 3 to 12: "); 
     sides = scan.nextInt(); 
    }

然后改变这

for (sides >= 3 || <= 12){ 
       System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides, poly);

到

for (int i = 0; i < sides; i++) 
    System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides, poly);

这将打印语句，有两边的次数。

输出：

Enter a number from 3 to 12: 1 
Please enter a number from 3 to 12: 2 
Please enter a number from 3 to 12: 3 
A polygon with 3 sides is called a(n) Triangle. 
A polygon with 3 sides is called a(n) Triangle. 
A polygon with 3 sides is called a(n) Triangle.

这看起来像功课虽然...你不想被抓住，询问有关答案在这里...

来源

2013-05-02 14:07:18 o0rebelious0o

感谢您的帮助，我为打破规则而道歉，我是新来的，并认为要求完整的解决方案是不被接受的。它不会再发生！ – amwindso 2013-05-02 14:13:14

while (sides > 3 || < 12)

应该

while (sides < 3 || sides > 12){ 
    System.out.println("Please enter a number from 3 to 12: "); 
    sides = scan.nextInt(); 
}

而且此块

for (sides >= 3 || <= 12){ 
      System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides, poly);//TODO:Use a 'for loop' here! 
    }

应该是：

System.out.printf("\nA polygon with"+ sides + "sides is called" + poly);

ñ o需要使用for循环来打印上面的语句。

来源

2013-05-02 13:56:00

不，它应该是while（双方<3 ||方面> 12） – filipko 2013-05-02 13:57:33

@filipko我没有看到你的评论和答案中的代码之间的区别。 – 2013-05-02 14:00:26

@Aleks G它被编辑过，之前写得不对。 – filipko 2013-05-02 14:05:32

使用此

Scanner scan = new Scanner(System.in); 
     int sides = 0; 
     String poly = "ERROR!!!!!!"; 

     System.out.print("Enter a number from 3 to 12: "); 
     sides = scan.nextInt(); 

     while (sides < 3 || sides > 12){ 
      System.out.println("Please enter a number from 3 to 12: "); 
      sides = scan.nextInt(); 
     } 


     if(sides == 3) { 
      poly = "Triangle"; 
     } else if(sides == 4) { 
      poly = "Quadrilaterl"; 
     } else if(sides == 5) { 
      poly = "Pentagon"; 
     } else if(sides == 6) { 
      poly = "Hexagon"; 
     } else if(sides == 7) { 
      poly = "Heptagon"; 
     } else if(sides == 8) { 
      poly = "Octagon"; 
     } else if(sides == 9) { 
      poly = "Nonagon"; 
     } else if(sides == 10) { 
      poly = "Decagon"; 
     } else if(sides == 12) { 
      poly = "Dodecagon"; 
     } 

     if (sides >= 3 || sides <= 12){ 
       System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides, poly);//TODO:Use a 'for loop' here! 
     } 

}

输出

Enter a number from 3 to 12: 0 
Please enter a number from 3 to 12: 1 
Please enter a number from 3 to 12: 5 

A polygon with 5 sides is called a(n) Pentagon.

来源

2013-05-02 13:59:39 NullPointerException

使用开关而不是多个条件。在while循环，你也需要阅读新的输入：

import java.util.Scanner; 
public class Lab6 { 
public static void main(String[] args) { 

Scanner scan = new Scanner(System.in); 
int sides = 0; 
String poly = "ERROR!!!!!!"; 

System.out.print("Enter a number from 3 to 12: "); 
sides = scan.nextInt(); 

while (sides < 3 || sides > 12){ 
    System.out.println("Please enter a number from 3 to 12: ") 
    sides = scan.nextInt(); 
} 

switch (sides){ 
    case 3: 
     poly = "Triangle"; 
     break; 
    case 4: 
     poly = "Quadrilaterl"; 
     break; 
    case 5: 
     poly = "Pentagon"; 
     break; 
    case 6: 
     poly = "Hexagon"; 
     break; 
    case 7: 
     poly = "Heptagon"; 
     break; 
    case 8: 
     poly = "Octagon"; 
     break; 
    case 9: 
     poly = "Nonagon"; 
     break; 
    case 10: 
     poly = "Decagon"; 
     break; 
    case 11: 
     poly = "Elevengon"; 
     break; 
    case 12: 
     poly = "Dodecagon"; 
     break; 
    } 

    System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides, poly); 
}

来源

2013-05-02 14:02:32 filipko

有很多问题，你的代码。鉴于其质量，我认为这是作业。

while (sides > 3 || < 12){ 
    System.out.println("Please enter a number from 3 to 12: ") 
}

即使你纠正的情况下，这将导致一个无限循环，因为一旦进入循环的条件的值不会改变。

for (sides >= 3 || <= 12){ 
    System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides, poly);//TODO:Use a 'for loop' here! 
}

请首先阅读for循环语法。你可以发布具体的问题。但是这看起来像是你写了一个if-陈述，校正员告诉你用for -loop代替。老实说，这不是他的意思。请尽量花时间了解您的程序应该如何工作。

来源

2013-05-02 14:03:41 Axel

既然你硬编码的答案，为什么不只是使用正确的答案数组？

import java.util.Scanner; 
public class Lab6 { 
    public static void main(String[] args) { 

     Scanner scan = new Scanner(System.in); 
     int sides = 0; 
     String[] polygonNames = {"invalid", "invalid", "Triangle", "Quadrilaterl", "Pentagon", "Hexagon", "Heptagon", "Octagon", "Nonagon", "Decagon", "Elevengon", "Dodecagon"}; 

     System.out.print("Enter a number from 3 to 12: "); 
     sides = scan.nextInt(); 

     while (sides < 3 || sides > 12){ 
      System.out.println("Please enter a number from 3 to 12: ") 
      sides = scan.nextInt(); 
     } 

     System.out.printf("\nA polygon with %d sides is called a(n) %s.", sides,  polygonNames[sides-1]); 
    } 
}

来源

2013-05-02 14:07:08

我需要使用for循环多次执行println（）

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