錯誤：java.lang.NumberFormatException

Question

我在修復代碼時遇到困難。 我收到的錯誤消息是：

線程“主”中的異常java.lang.NumberFormatException：對於輸入字符串：Lab3處java.lang.Double.parseDouble（未知源）處sun.misc.FloatingDecimal.readJavaFormatString（未知源）處的輸入字符串為“ 60 45 100 30 20”。主要（Lab3.java:15）

這是我的代碼：

import java.io.*;
import java.math.*;

public class Lab3 
{
    public static void main(String[] args) throws IOException
    {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        double pVelocity, pAngle, tDistance, tSize, tElevation;
        double radians, time, height, pDistance;
        String input = br.readLine();

        String[] values = input.split("\\+");
        pVelocity = Double.parseDouble(values[0]);
        pAngle = Double.parseDouble(values[1]);
        tDistance = Double.parseDouble(values[2]);
        tSize = Double.parseDouble(values[3]);
        tElevation = Double.parseDouble(values[4]);

        while(pVelocity != 0 && pAngle != 0 && tDistance != 0 && tSize != 0 && tElevation != 0)
        {
            radians = pAngle*(Math.PI/180);
            time = tDistance/(pVelocity*Math.cos(radians));
            height = (pVelocity*time*Math.sin(radians))-(32.17*time*time)/2;
            pDistance = time*(pVelocity*Math.cos(radians));

            if(pVelocity*Math.cos(radians) == 0)
                System.out.print("The computed distance cannot be calculated with the given data.");
            else if(height > tElevation && height <= tSize)
                System.out.print("The target was hit by the projectile.");
            else if(height < tElevation)
                System.out.print("The projectile was too low.");
            else if(height > tSize)
                System.out.print("The projectile was too high.");
            else if(pDistance < tDistance)
                System.out.print("The computed distance was too short to reach the target.");
            else if(height < 0)
                System.out.println("The projectile's velocity is " + pVelocity + "feet per second.");
                System.out.println("The angle of elevation is " + radians +"degrees.");
                System.out.println("The distance to the target is " + tDistance + "feet.");
                System.out.println("The target's size is " + tSize + "feet.");
                System.out.println("The target is located " + tElevation + "feet above the ground.");
        }
    }
}

我相信我已經將我的double變量正確地解析為字符串變量，並且Eclipse在編譯時沒有顯示更多錯誤。 誰能建議解決這個問題的方法？

Answer 1

您嘗試解析"60 45 100 30 20"的輸入不是數字。

嘗試在空間上分割輸入並解析每個元素：

for (String s : input.split(" ")) {
    // parse s
}

也許您的意思是"\\\\s+" （一個或多個空格）而不是"\\\\+" （單個加號）。

Answer 2

您在input.split("\\\\+");缺少s input.split("\\\\+"); 。 應該是input.split("\\\\s+"); 。 您執行此操作的方式不會拆分任何內容，而將pVelocity為"60 45 100 30 20" ，這不是數字，因此

java.lang.NumberFormatException: For input string: "60 45 100 30 20"