Java の素数: 素数 は 1 より大きく、1 またはそれ自体で除算した数値です。言い換えれば、素数はそれ自身または 1 以外の数で割ることはできません。たとえば、2、3、5、7、11、13、17... は素数です。
注: 0 と 1 は素数ではありません。他のすべての偶数は 2 で割ることができるため、2 は唯一の偶数の素数です。
Javaの素数プログラムを見てみましょう。この Java プログラムでは、数値変数を取得し、その数値が素数かどうかを確認します。
public class PrimeExample{ public static void main(String args[]){ int i,m=0,flag=0; int n=3;//it is the number to be checked m=n/2; if(n==0||n==1){ System.out.println(n+' is not prime number'); }else{ for(i=2;i<=m;i++){ if(n%i="=0){" system.out.println(n+' is not prime number'); flag="1;" break; } if(flag="=0)" { end of else < pre> <span> Test it Now </span> <p>Output:</p> <pre> 3 is prime number </pre> <h2>Prime Number Program using Method in Java</h2> <pre> public class PrimeExample2{ static void checkPrime(int n){ int i,m=0,flag=0; m=n/2; if(n==0||n==1){ System.out.println(n+' is not prime number'); }else{ for(i=2;i<=m;i++){ if(n%i="=0){" system.out.println(n+' is not prime number'); flag="1;" break; } if(flag="=0)" { end of else public static void main(string args[]){ checkprime(1); checkprime(3); checkprime(17); checkprime(20); < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 is not prime number 3 is prime number 17 is prime number 20 is not prime number </pre> <h2>Prime Number Program in Java (Another way)</h2> <p>You can also use a method where number is not predefined. Here, user has to put the number to check if the number is prime.</p> <pre> import java.util.Scanner; import java.util.Scanner; public class PrimeExample3 { public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.print('Enter a number : '); int n = s.nextInt(); if (isPrime(n)) { System.out.println(n + ' is a prime number'); } else { System.out.println(n + ' is not a prime number'); } } public static boolean isPrime(int n) { if (n <= 1) { return false; } for (int i="2;" < math.sqrt(n); i++) if (n % 0) true; pre> <p>Output:</p> <strong>Use image PrimeExample1</strong> <h2>Find prime numbers between two numbers</h2> <p>You can also find prime numbers between two specified numbers.</p> <pre> import java.util.Scanner; public class PrimeExample4 { public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.print('Enter the first number : '); int start = s.nextInt(); System.out.print('Enter the second number : '); int end = s.nextInt(); System.out.println('List of prime numbers between ' + start + ' and ' + end); for (int i = start; i <= end; i++) { if (isprime(i)) system.out.println(i); } public static boolean isprime(int n) (n <="1)" return false; for (int i="2;" % 0) true; pre> <p>Output:</p> <strong>Use image PrimeExample2</strong> </=></pre></=></pre></=m;i++){></pre></=m;i++){> Javaのメソッドを使用した素数プログラム
public class PrimeExample2{ static void checkPrime(int n){ int i,m=0,flag=0; m=n/2; if(n==0||n==1){ System.out.println(n+' is not prime number'); }else{ for(i=2;i<=m;i++){ if(n%i="=0){" system.out.println(n+\' is not prime number\'); flag="1;" break; } if(flag="=0)" { end of else public static void main(string args[]){ checkprime(1); checkprime(3); checkprime(17); checkprime(20); < pre> <span> Test it Now </span> <p>Output:</p> <pre> 1 is not prime number 3 is prime number 17 is prime number 20 is not prime number </pre> <h2>Prime Number Program in Java (Another way)</h2> <p>You can also use a method where number is not predefined. Here, user has to put the number to check if the number is prime.</p> <pre> import java.util.Scanner; import java.util.Scanner; public class PrimeExample3 { public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.print('Enter a number : '); int n = s.nextInt(); if (isPrime(n)) { System.out.println(n + ' is a prime number'); } else { System.out.println(n + ' is not a prime number'); } } public static boolean isPrime(int n) { if (n <= 1) { return false; } for (int i="2;" < math.sqrt(n); i++) if (n % 0) true; pre> <p>Output:</p> <strong>Use image PrimeExample1</strong> <h2>Find prime numbers between two numbers</h2> <p>You can also find prime numbers between two specified numbers.</p> <pre> import java.util.Scanner; public class PrimeExample4 { public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.print('Enter the first number : '); int start = s.nextInt(); System.out.print('Enter the second number : '); int end = s.nextInt(); System.out.println('List of prime numbers between ' + start + ' and ' + end); for (int i = start; i <= end; i++) { if (isprime(i)) system.out.println(i); } public static boolean isprime(int n) (n <="1)" return false; for (int i="2;" % 0) true; pre> <p>Output:</p> <strong>Use image PrimeExample2</strong> </=></pre></=></pre></=m;i++){> Java での素数プログラム (別の方法)
数値が事前定義されていない方法を使用することもできます。ここで、ユーザーは数値を入力して、その数値が素数かどうかを確認する必要があります。
import java.util.Scanner; import java.util.Scanner; public class PrimeExample3 { public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.print('Enter a number : '); int n = s.nextInt(); if (isPrime(n)) { System.out.println(n + ' is a prime number'); } else { System.out.println(n + ' is not a prime number'); } } public static boolean isPrime(int n) { if (n <= 1) { return false; } for (int i="2;" < math.sqrt(n); i++) if (n % 0) true; pre> <p>Output:</p> <strong>Use image PrimeExample1</strong> <h2>Find prime numbers between two numbers</h2> <p>You can also find prime numbers between two specified numbers.</p> <pre> import java.util.Scanner; public class PrimeExample4 { public static void main(String[] args) { Scanner s = new Scanner(System.in); System.out.print('Enter the first number : '); int start = s.nextInt(); System.out.print('Enter the second number : '); int end = s.nextInt(); System.out.println('List of prime numbers between ' + start + ' and ' + end); for (int i = start; i <= end; i++) { if (isprime(i)) system.out.println(i); } public static boolean isprime(int n) (n <="1)" return false; for (int i="2;" % 0) true; pre> <p>Output:</p> <strong>Use image PrimeExample2</strong> </=></pre></=>