[JAVA] 랜덤(Random) 수 구현(자바)

Math.random()

package Java;

public class MathRandom {
	public static void main(String[] args) {
		int N = 10;
		// 0.0 <= doubleType1 < 1.0
		double doubleType1 = Math.random();
		// 0.0 <= doubleType2 < N.0
		double doubleType2 = Math.random()*N;
		// 0 <= intType1 < N-1
		int intType1 = (int)Math.random();
		// 1 <= intType2 < N
		int intType2 = (int)(Math.random()*N)+1;
				
		System.out.println(doubleType1);
		System.out.println(doubleType2);
		System.out.println(intType1);
		System.out.println(intType2);
	}
}

● 출력
0.34195757462794074
8.491476117299866
0
2

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Random rand  = new Random();

package Java;

import java.util.Random;

public class ClassRandom {
	public static void main(String[] args) {
		int N = 10;
		Random rand = new Random();
		// 0 <= intType1 < N
		int intType1 = rand.nextInt(N);
		// 1 <= intType2 <= N
		int intType2 = rand.nextInt(N)+1;
		
		System.out.println(intType1);
		System.out.println(intType2);
	}
}

● 출력
9
7

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