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我的任务：

通过确保用户输入一个正整数表示英尺、一个非负十进制数表示英寸以及一个正十进制数表示重量来执行输入验证。有关详细信息，请参阅示例会话。特别要注意回波打印的身高和体重值以及生成的身体质量指数值的格式。

我的程序有效，但我不知道如何使它看起来像下面的示例程序。我必须让用户输入以英尺为单位的高度，然后是空间，然后是英寸。我不知道如何在空间分割用户输入。

示例会话：

Enter height using feet space inches (e.g., 5 6.25): hi there
Invalid feet value. Must be an integer.
Invalid inches value. Must be a decimal number.
Re-enter height using feet space inches (e.g., 5 6.25): 0 9
Invalid feet value. Must be positive.
Re-enter height using feet space inches (e.g., 5 6.25): 5.25 0
Invalid feet value. Must be an integer.
Re-enter height using feet space inches (e.g., 5 6.25): 5 9.25
Enter weight in pounds: 0
Invalid pounds value. Must be positive.
Re-enter weight in pounds: 150.5
height = 5'-9.25"
weight = 150.5 pounds
body mass index = 22.1

到目前为止我的代码：

package ch14;
import java.util.Scanner;

public class BMI {


public static void main(String[] args) {

    String inputString;
    double bmi;
    double pounds;
    double inches;
    String feet;

    Scanner stdIn = new Scanner(System.in);

    System.out.print("Please enter height using feet space inches (e.g., 5 6.25): ");
    inputString = stdIn.nextLine();


    try
    {
        Double.parseDouble(inputString);
    }
    catch(NumberFormatException nfe)
    {
        System.out.println ("Invalid inch value. Number must be a decimal.");
        System.out.print ("Re-enter height in inches: ");
        inputString = stdIn.nextLine ();
    }

    inches=Double.parseDouble(inputString);

    if(inches<=0)
    {
        System.out.println("Invalid inch value. Must be a positive number.");
        System.out.print("Re-enter height in inches:");
        inputString = stdIn.nextLine();
        inches=Double.parseDouble(inputString);
    }

    System.out.print("enter weight(in pounds) ");
    inputString = stdIn.nextLine();

    try
    {
        Double.parseDouble(inputString);
    }
    catch(NumberFormatException nfe)
    {
        System.out.println("Invalid pound value. Number must be a decimal.");
        System.out.print("Re-enter the weight in pounds: ");
        inputString = stdIn.nextLine();
    }

    pounds=Double.parseDouble(inputString);

    if(pounds <= 0)
    {
        System.out.println("Invalid pound value. Must be a positive number.");
        System.out.print("Re-enter the weight in pounds:");
        inputString = stdIn.nextLine();
        pounds=Double.parseDouble(inputString);
    }

    System.out.println("Height = " + inches + "\"");
    System.out.println("Weight = " + pounds + " pounds");
    System.out.printf("Body Mass Index = %.1f\n",(pounds * 703.)/(inches * inches));

    }//end main
}
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1 回答 1

2

您使用.split进行拆分，因此，对于单个空格...

mystring.split("\\s");

对于任意数量的空间...

mystring.split("\\s+");

这两个操作都返回一个字符串数组，然后可以像任何其他数组一样访问它，例如......

String mystring = "Hello World";
String[] words = mystring.split("\\s");
System.out.println(words[0]); //<--- Would print "Hello"

对于您的特定问题，您可能需要将这些 String 对象转换为 Double 之类的。您可以使用Double.parseDouble(). 例如，

Double number = Double.parseDouble("1.0");

上面这行代码将"1.0"String 对象转换为 value 的双精度值1.0。

于 2012-04-25T11:12:01.670 回答