Nbody模拟器java.util.InputMismatchException

时间:2019-12-31 06:38:12

标签: java

我正在通过参与UC Berkeley的2016年春季CS61B的一些项目来学习Java。 我正在这里概述的Nbody项目的“ readBodies”功能中: https://sp19.datastructur.es/materials/proj/proj0/proj0#readbodies

我跑步

javac Body.java NBody.java TestReadBodies.java

然后

java TestReadBodies

使用TestReadBodies测试我编写的NBody程序。然后,我得到了:

Checking readBodies...
Exception in thread "main" java.util.InputMismatchException
        at java.base/java.util.Scanner.throwFor(Scanner.java:939)
        at java.base/java.util.Scanner.next(Scanner.java:1594)
        at java.base/java.util.Scanner.nextDouble(Scanner.java:2564)
        at In.readDouble(In.java:270)
        at NBody.readBodies(NBody.java:17)
        at TestReadBodies.checkReadBodys(TestReadBodies.java:21)
        at TestReadBodies.main(TestReadBodies.java:93)

我认为问题可能是我的阅读类型错误,所以我改变了

的类型
double xPP = in.readDouble();
            double yPP = in.readDouble();
            double xVV = in.readDouble();
            double yVV = in.readDouble();
            double masss = in.readDouble();

转换为int,long和short,但似乎不起作用。我必须使用“ In”类来解决此问题。这是完整的文档:

https://introcs.cs.princeton.edu/java/stdlib/javadoc/In.html

我也不允许使用

System.exit(0)

这是Nbody.java

public class NBody {
    public static double readRadius(String fileName) {
        In in = new In(fileName);
        in.readInt();
        double radius = in.readDouble();
        return radius;
    }
    public static Body[] readBodies(String fileName) {
        In in = new In(fileName);
        int size = in.readInt();

        Body[] list = new Body[size];
        int count = 0;
        double test = in.readDouble();

        while(!in.isEmpty()) {
            double xPP = in.readDouble();
            double yPP = in.readDouble();
            double xVV = in.readDouble();
            double yVV = in.readDouble();
            double masss = in.readDouble();
            String imgFilee = in.readString();
            Body planett = new Body(xPP, yPP, xVV, yVV, masss, imgFilee);
            list[count] = planett;
            count += 1;
        }
        return list;
    }

这是TestReadBodies.java

/**
 *  Tests Nbody.readBodies. Reads in ./data/planets.txt and checks output of
 *  readBodies().
 */
public class TestReadBodies {

    private static boolean doubleEquals(double actual, double expected, double eps) {
        if (Double.isNaN(actual) || Double.isInfinite(actual)) {
            return false;
        } else {
            return Math.abs(expected - actual) <= eps * Math.max(expected, actual);
        }
    }

    /** Checks to make sure that readBodies() works perfectly. */
    private static String checkReadBodys() {
        System.out.println("Checking readBodies...");
        String planetsTxtPath = "./data/planets.txt";
        /* If the following line fails to compile, you probably need to make
         * a certain method static! */
        Body[] actualOutput = NBody.readBodies(planetsTxtPath);

        /* Check the simple things: */
        if (actualOutput == null) {
            return "FAIL: readBodies(); null output";
        }
        if (actualOutput.length != 5) {
            return "FAIL: readBodies().length: Expected 5 and you gave " + actualOutput.length;
        }

        /* Check to make sure every planet exists, plus random spot checks */
        boolean foundEarth = false;
        boolean foundMars = false;
        boolean foundMercury = false;
        boolean foundSun = false;
        boolean foundVenus = false;
        boolean randomChecksOkay = true;
        for (Body p : actualOutput) {
            if ("earth.gif".equals(p.imgFileName)) {
                foundEarth = true;
                if (!doubleEquals(p.xxPos, 1.4960e+11, 0.01)) {
                    System.out.println("Advice: Your Earth doesn't have the right xxPos!");
                    randomChecksOkay = false;
                }
            } else if ("mars.gif".equals(p.imgFileName)) {
                foundMars = true;
            } else if ("mercury.gif".equals(p.imgFileName)) {
                foundMercury = true;
                if (!doubleEquals(p.yyPos, 0, 0.01)) {
                    System.out.println("Advice: Your Mercury doesn't have the right yyPos!");
                    randomChecksOkay = false;
                }
            } else if ("sun.gif".equals(p.imgFileName)) {
                foundSun = true;
            } else if ("venus.gif".equals(p.imgFileName)) {
                foundVenus = true;
                if (!doubleEquals(p.mass, 4.8690e+24, 0.01)) {
                    System.out.println("Advice: Your Venus doesn't have the right mass!");
                    randomChecksOkay = false;
                }
            }
        }

        /* Build up a nice list of missing planets */
        String missingBodys = "";
        if (!foundEarth) {
            missingBodys += "Earth, ";
        }
        if (!foundMars) {
            missingBodys += "Mars, ";
        }
        if (!foundMercury) {
            missingBodys += "Mercury, ";
        }
        if (!foundSun) {
            missingBodys += "Sun, ";
        }
        if (!foundVenus) {
            missingBodys += "Venus, ";
        }
        if (missingBodys.length() > 0) {
            String answer = "FAIL: readBodies(); Missing these planets: ";
            answer += missingBodys.substring(0, missingBodys.length() - 2);
            return answer;
        }
        if (!randomChecksOkay) {
            return "FAIL: readBodies(); Not all planets have correct info!";
        }
        return "PASS: readBodies(); Congrats! This was the hardest test!";
    }

    public static void main(String[] args) {
        String testResult = checkReadBodys();
        System.out.println(testResult);
    }
}

请让我知道为什么会出现此错误,以及如何在Nbody.java中修复它。

非常感谢您!

0 个答案:

没有答案
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