Java 从一组数据随机选择并可设置出现概率

import java.util.HashMap;
import java.util.Map;
import java.util.Random;



public class Test {

    //String 可以为任意类型 也可以自定义类型
    static Map<String, Integer> keyChanceMap = new HashMap<String,Integer>();
    static{
        keyChanceMap.put("出现比例为10的", 10);
        keyChanceMap.put("出现比例为100的", 100);
        keyChanceMap.put("出现比例为500的", 500);
        keyChanceMap.put("出现比例为1000的", 1000);
        keyChanceMap.put("出现比例为10000的", 10000);
    }
    
    public static void main(String[] args) {
        Map<String, Integer> count = new HashMap<String,Integer>();
        for (int i = 0; i < 100000; i++) {
            
            
            String item = chanceSelect(keyChanceMap);
            
            if (count.containsKey(item)) {
                count.put(item, count.get(item) + 1);
            } else {
                count.put(item, 1);
            }
        }
        
        for(String id : count.keySet()){
            System.out.println(id+"\t出现了 "+count.get(id)+" 次");
        }
    }

    
    public static String chanceSelect(Map<String, Integer> keyChanceMap) { 
        if(keyChanceMap == null || keyChanceMap.size() == 0)  
             return null;  
          
        Integer sum = 0;  
        for (Integer value : keyChanceMap.values()) {  
             sum += value;  
        }  
        // 从1开始  
        Integer rand = new Random().nextInt(sum) + 1;  
          
        for (Map.Entry<String, Integer> entry : keyChanceMap.entrySet()) {
            rand -= entry.getValue();
            // 选中
            if (rand <= 0) {
                String item = entry.getKey();
                return item;
            }
        } 
          
        return null;  
   }
}