JAVA随机产生4或6位随机数

迷南。 2023-10-03 20:38 37阅读 0赞

package com.bgs.utils;
    
    import java.text.DecimalFormat;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Random;
    
    /**
     * 获取随机数
     * 
     * @author qianyi
     *
     */
    public class RandomUtil {
    
    	private static final Random random = new Random();
    
    	private static final DecimalFormat fourdf = new DecimalFormat("0000");
    
    	private static final DecimalFormat sixdf = new DecimalFormat("000000");
    
    	public static String getFourBitRandom() {
    		return fourdf.format(random.nextInt(10000));
    	}
    
    	public static String getSixBitRandom() {
    		return sixdf.format(random.nextInt(1000000));
    	}
    
    	/**
    	 * 给定数组，抽取n个数据
    	 * @param list
    	 * @param n
    	 * @return
    	 */
    	public static ArrayList getRandom(List list, int n) {
    
    		Random random = new Random();
    
    		HashMap<Object, Object> hashMap = new HashMap<Object, Object>();
    
    		// 生成随机数字并存入HashMap
    		for (int i = 0; i < list.size(); i++) {
    
    			int number = random.nextInt(100) + 1;
    
    			hashMap.put(number, i);
    		}
    
    		// 从HashMap导入数组
    		Object[] robjs = hashMap.values().toArray();
    
    		ArrayList r = new ArrayList();
    
    		// 遍历数组并打印数据
    		for (int i = 0; i < n; i++) {
    			r.add(list.get((int) robjs[i]));
    			System.out.print(list.get((int) robjs[i]) + "\t");
    		}
    		System.out.print("\n");
    		return r;
    	}
    }

没什么难度就不解释了 封装class后直接引用就ok