Java:在方法 main 中调用方法

Question

仅供参考：我是初学者。另外，我知道调用方法是一个新手概念，并且已经有一些这样的线程。我的情况有点不同，因为我受到伪代码的限制，我的程序必须以相同的方式镜像。我在从其他方法调用方法时遇到问题，包括从 main 内部调用方法。下面是伪代码，后跟我编写的代码：

伪代码：

// The user enters an integer and the program calculates that many primes
// It uses 3 methods, including the main. All the methods are in the same class
// and should be declared as ‘public static.’
Project Print the First n Primes
    Package printTheFirstNPrimesPackage
        Class PrintTheFirstNPrimes
            Method Main
                Declare numberOfPrimes as integer
Print “How many prime numbers do you want?"
                Read numberOfPrimes from the keyboard
                Call the method: PrintNPrimes(numberOfPrimes)
            end Method (Main)
//          ***********************************************************
//           This method accepts an integer and prints that many prime
//            numbers, starting at 2. 2 is the lowest primt number. 
//          ***********************************************************
            Method void PrintNPrimes(int n)
                declare i as integer
                declare myNum as integer
                myNum = 2   // The first prime number
                i = 0
                loop while i < n    // This could be a ‘for’ loop
                if IsPrime(myNum)   // Call the Isprime method, (see below)
                    i = i + 1
                    print myNum
                End If
                myNum = myNum + 1
                end loop
            end Method PrintNPrimes
//          **********************************************************
//          This method accepts an integer and tests to see if it is 
//            a prime number. If it is prime, the method returns true,
//             otherwise it returns false.
//          **********************************************************
            Method boolean IsPrime(int number)
                Declare result as boolean
                result = true
                declare i as integer
                i = 2
                loop while i < number
                    if ((number % i) == 0)
                        result = false
                        exit loop
                    end if
                end loop
                return result
            end Method
        end Class
    End Package
End Project

JAVA代码：

package printTheFirstNPrimesPackage;
import java.util.*;
public class PrintTheFirstNPrimes {
    public static void main(String [] args) {
        int numberOfPrimes;
        Scanner primes = new Scanner(System.in);
        System.out.println("How many prime numbers do you want?");
        numberOfPrimes = primes.nextInt();
        // Call the method PrintNPrimes(numberOfPrimes)
    }
    public static void PrintNPrimes(int n) {
        int i;
        int myNum;
        myNum = 2; // The first prime number
        i = 0; {
        while (i < n) 
//      if IsPrime(myNum) // Call the IsPrime method (see below) {
                i = i + 1;
                System.out.println(myNum);
        myNum = myNum + 1;
        }
    }
    public static boolean IsPrime(int number) {
        boolean result;
        result = true;
        int i = 2;
        while (i < number) {
            if ((number % 1) == 0)
                result = false;
            }
        return result;
        }
    }

我的主要问题是在 if 语句中调用 IsPrime 方法。我收到一个错误，说 IsPrime 无法从 int 转换为我知道的布尔值，但伪代码限制了我做其他事情。我还想了解如何在方法 main 中调用 PrintNPrimes 方法的建议。谢谢。

Answer 1

因为你的PrintNPrimes是静态方法，所以你可以通过传递numberofPrimes来调用该方法。

例：

 public static void main(String [] args) {
        int numberOfPrimes;
        Scanner primes = new Scanner(System.in);
        System.out.println("How many prime numbers do you want?");
        numberOfPrimes = primes.nextInt();
       PrintNPrimes(numberOfPrimes);
    }
  ..........

注意：Java 命名约定建议在定义方法时使用首字母作为小写字母。

您可以按照相同的方法来调用其他方法。

Answer 2

if IsPrime（myNum）

需要

if （IsPrime（myNum））

还要确保恢复您的大括号。我看不出这会导致错误的任何原因。如果您仍有问题，请发布确切的错误消息。

Answer 3

更新下面的代码，解决编译错误的两个（包括 if 语句）：

printNPrimes(numberOfPrimes);

if (isPrime(myNum)) // Call the IsPrime method (see below) {

完整更新的代码：

public static void main(String [] args) {
    int numberOfPrimes;
    Scanner primes = new Scanner(System.in);
    System.out.println("How many prime numbers do you want?");
    numberOfPrimes = primes.nextInt();
    printNPrimes(numberOfPrimes);
}
public static void printNPrimes(int n) {
    int i;
    int myNum;
    myNum = 2; // The first prime number
    i = 0; {
    while (i < n) 
     if (isPrime(myNum)) // Call the IsPrime method (see below) {
            i = i + 1;
            System.out.println(myNum);
    myNum = myNum + 1;
    }
}
public static boolean isPrime(int number) {
    boolean result;
    result = true;
    int i = 2;
    while (i < number) {
        if ((number % 1) == 0)
            result = false;
        }
    return result;
}

我没有检查逻辑。