Java实现的抽取随机号码或者出场顺序--整理老文章格式

本程序可以实现抽取随机号码或者抽取出场顺序

详情请看注释。

import java.util.Arrays;
import java.util.Scanner;
public class Drawing {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.println("Please input the number you need to draw:");
		int k = sc.nextInt();
		System.out.println("Please input the number you can draw:");
		int n = sc.nextInt();
		int temp_n = n;//store n represent :when n==k,this is a problem focus
		//on sequence of drawing numbers.
		if (k > n) {
			System.out.println("K can not more than N!");
			System.exit(-1);
		}
	
		// 初始化抽取数组
		int[] numbers = new int[n];
		for (int i = 0; i < n; i++) {
			numbers[i] = i + 1;
		}
		int[] result = new int[k];
		for (int i = 0; i < k; i++) {
		// produce a number between 0~n-1
			int r = (int) (Math.random() * n);
			result[i] = numbers[r];
			// move the last element to the random location,
			// in case drawing the same number
			numbers[r] = numbers[n - 1];
			n--;
		}
		//假设n与k相等就是抽取出场顺序
		if (temp_n != k) {
			Arrays.sort(result);
		}
		System.out.println("Result as following:"+Arrays.toString(result));
		for (int a : result) {
			System.out.println(a);
		}
	}
}