在 Java 中檢查一個數字是否是質數
Sheeraz Gul
2023年1月30日
2022年4月22日
在 Java 中，我們可以實現不同的方法來檢查一個數字是否是質數。本教程演示了檢查數字是否為質數的不同方法。
在 Java 中使用 while 迴圈檢查一個數是否為質數
你可以使用 while 迴圈開發一種方法來檢查輸入數字是否為質數。
示例程式碼：
package delftstack;
import java.util.Scanner;
public class Is_Prime {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number you want to check :");
int Input_Number = sc.nextInt();
int temp = 2;
boolean condition = false;
while (temp <= Input_Number / 2) {
// condition to check for a non-prime number
if (Input_Number % temp == 0) {
condition = true;
break;
}
++temp;
}
if (!condition) {
System.out.println("The Number " + Input_Number + " is a prime number.");
}
else {
System.out.println("The Number " + Input_Number + " is not a prime number.");
}
}
}
輸出：
Enter the number you want to check:
11
The Number 11 is a prime number.
或者，
Enter the number you want to check:
90
The Number 90 is not a prime number.
在 Java 中使用 for 迴圈檢查一個數是否為質數
你還可以利用 for 迴圈建立一個方法來檢查輸入數字是否為質數。
示例程式碼：
package delftstack;
import java.util.Scanner;
public class Is_Prime {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number you want to check: ");
int Input_Number = sc.nextInt();
boolean condition = false;
for (int x = 2; x <= Input_Number / 2; ++x) {
// condition to check for a non-prime number
if (Input_Number % x == 0) {
condition = true;
break;
}
}
if (!condition) {
System.out.println("The Number " + Input_Number + " is a prime number.");
}
else {
System.out.println("The Number " + Input_Number + " is not a prime number.");
}
}
}
輸出：
Enter the number you want to check:
3
The Number 3 is a prime number.
在 Java 中建立一個方法來檢查一個數字是否為質數
我們將建立一個名為 isPrime() 的方法，並使用它來檢查輸入數字是否為質數。
示例程式碼：
package delftstack;
import java.util.Scanner;
public class Is_Prime {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Enter the number you want to check: ");
int Input_Number = sc.nextInt();
if (isPrime(Input_Number)) {
System.out.println("The Number " + Input_Number + " is a prime number.");
}
else {
System.out.println("The Number " + Input_Number + " is not a prime number.");
}
}
static boolean isPrime(int input_number){
if (input_number <= 1) {
return false;
}
// check for a non-prime number
for (int x = 2; x < input_number; x++) {
if (input_number % x == 0) {
return false;
}
}
return true;
}
}
輸出：
Enter the number you want to check:
10
The Number 10 is not a prime number.
Author: Sheeraz Gul
Sheeraz is a Doctorate fellow in Computer Science at Northwestern Polytechnical University, Xian, China. He has 7 years of Software Development experience in AI, Web, Database, and Desktop technologies. He writes tutorials in Java, PHP, Python, GoLang, R, etc., to help beginners learn the field of Computer Science.
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