Question

这是我编程的家庭作业，它成功编译但是当我尝试运行它时，输出看起来不像它应该如何。对我所犯错误的任何建议都将不胜感激。感谢

import java.util.Scanner;
/***********************************
 * Class: FRUnit5.java
 * Author: Robert Frankele
 *
 * Description: Ask user to enter the maximum random number of rounds (2-8).
 * Then ask the user how many rounds they would like to execute (1-8).
 * Display the results in formatted columns as follows:
 * (example using 8 as max random number, and 2 and number of rounds)
 *
 * Round    Rand #      Rand^Round      Modulus     Rand/Round
 *     1         7               7            0           7.00
 *     2         4              16            0           2.00
 */
public class FRUnit5
{

    public static void main(String[] args)
    {
        // Create a Scanner object for user input: 2pts
        Scanner userInput = new Scanner(System.in);
        // Variable to hold user's input for maximum random number: 2pts
        double maxRandNum;
        // Variable to hold the number of rounds the user wishes to execute: 2pts
        double numRound;
        double maxRound;

        // Variable to hold the random number generated from the Math class
        // using the user's maximum random number as an argument: 2pts
        double randNumMath;
        // Ask the user to enter the maximum random number to use (2-8): 2pts
        System.out.print("Enter the maximum random number to use ");
        // Store the number they entered into the variable declared above: 2pts
        maxRandNum = userInput.nextInt();
        // Clear the buffer
        userInput.nextLine();

        // Check to see if the number they entered is greater than 8: 5pts
        // If it is, display an error message and assign 8 as the maximum random number (see project example): 3pts
        // Then, assign 8 to the variable declared above that will hold the maximum random number: 3pts
            if (maxRandNum > 8)
        {
            System.out.println("The maximum random number has to be <= 8");
            maxRandNum = 8;
        }

        // Ask the user to enter the number of rounds they wish to execute.: 2pts
        System.out.print("Enter the number of rounds you wish to execute ");
        // Store the number they entered into the variable declared above: 2pts
        numRound = userInput.nextInt();

        // Print the header of the output, using the printf method: 8pts
        // Round    Rand #      Rand^Round      Modulus     Rand/Round
        System.out.printf("%10s%10s%15s%12s%15s\n", "Round", "Rand #", "Rand^Round", "Modulus", "Rand/Round");

        // Set up a for loop to iterate through the number of rounds: 10pts

        maxRound = 9;
        for (numRound = 0; numRound < maxRound; numRound++)
        {
            // Calculate the random number given the maximum random number, and store in a local variable called randomNum: 5pts
            int randomNum = (int) (Math.random() * maxRandNum + 1);


            // Calculate the Rand^Round number, using Math.pow(randomNum, round) as the equation,
            // and store in a local variable called randToRound: 5pts
            double randToRound = (Math.pow(randomNum, numRound));

            // Calculate the modulus: randomNum % round, and store in a variable called modulusOfRand: 3pts
            double modulusOfRand = randomNum % numRound;

            // Calculate randomNum / round and store in a variable called randDivRound: 3pts
            double randDivRound = randomNum / numRound;

            // Using printf, display the results, remembering to only display randDivRound with two places after the decimal point: 10pts
            System.out.printf("%10d%10d%15d%12d%15.2f\n", numRound, randomNum, randToRound, modulusOfRand, randDivRound);

        }

    } // end of main
} // end of class

这就是我所看到的：输入要使用的最大随机数9 最大随机数必须<= 8 输入您要执行的回合数6 Round Rand＃Rand ^ Round Modulus Rand / Round 线程“main”中的异常java.util.IllegalFormatConversionException：d！= java.lang.Double at java.util.Formatter $ FormatSpecifier.failConversion（Formatter.java:4302） at java.util.Formatter $ FormatSpecifier.printInteger（Formatter.java:2793） at java.util.Formatter $ FormatSpecifier.print（Formatter.java:2747）在java.util.Formatter.format（Formatter.java:2520）在java.io.PrintStream.format（PrintStream.java:970）在java.io.PrintStream.printf（PrintStream.java:871）在FRUnit5.main（FRUnit5.java:76）按任意键继续。。

Answer 1

似乎你得到的是java.util.IllegalFormatConversionException。

请确保在%f中使用%d而不是printf()作为double类型的变量，因为%d在Java中使用十进制整数。

改变这个：

System.out.printf("%10d%10d%15d%12d%15.2f\n", numRound, randomNum, randToRound, modulusOfRand, randDivRound);

到此：

System.out.printf("%10f%10d%15f%12f%15.2f\n", numRound, randomNum, randToRound, modulusOfRand, randDivRound);

Answer 2

程序失败的原因是System.out.printf（）方法中的格式。您已将变量randToRound，modulusOfRand定义为double，但您尝试使用格式化程序中的％10d将它们格式化为int。

请添加System.out.print（）以检查变量的值并在System.out.printf（）中添加适当的格式，这可以解决您的问题。

可能的解决方案：

System.out.printf("%10d%10d%15d%12d%15.2f\n", (int)numRound, randomNum, (int)randToRound, (int)modulusOfRand,
                    randDivRound);

你的numRound循环应该从1开始，循环通过numRound当前逻辑将运行循环9次，这不是问题陈述中的预期。

我的代码编译，但没有显示预期的输出

2 个答案: