[英]Java: calling a method in method main
僅供參考:我是初學者。 另外,我理解調用方法是一個新手概念,並且已經有一些這樣的線程。 我的情況有點不同,因為我受到偽代碼的限制,我的程序必須完全相同。 我無法從其他方法調用方法,包括從main內部調用方法。 這是偽代碼,后跟我寫的代碼:
偽代碼:
// 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代碼:
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;
}
}
我的主要問題是在if語句中調用IsPrime方法。 我得到一個錯誤,說IsPrime不能從int轉換為我知道的boolean,但是偽代碼限制我做其他事情。 我也想了解如何在方法main中調用PrintNPrimes方法。 謝謝。
因為您的PrintNPrimes
是靜態方法,所以您可以通過傳遞numberofPrimes
來調用該方法。
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命名約定建議在定義方法時使用第一個字母作為小寫字母。
您可以按照相同的方法調用其他方法。
如果IsPrime(myNum)
需要是
if(IsPrime(myNum))
還要確保恢復花括號。 我沒有看到任何原因導致錯誤。 如果您仍有問題,請發布確切的錯誤消息。
更新下面的代碼, 包含編譯錯誤的兩個(包括if語句)的解決方案:
printNPrimes(numberOfPrimes);
if (isPrime(myNum)) // Call the IsPrime method (see below) {
完整更新的代碼:
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;
}
我沒有檢查邏輯。
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