Java 利用binarySearch实现抽奖计算逻辑

public class GetIndex {
	private int weightAdder ; //权值加法器基数
	private int index ; //权值加法器填充时下标
	private int dex; //中奖值下标
	private int max; //最大权值
	private int random;
	private Random ran;
	private ArrayList<String> record = new ArrayList<String>();
	private int[] weights; //权值加法器数组
	public static DecimalFormat df = new DecimalFormat("0.00"); //格式化数值
	public static int[] map = new int[] {10,8450,1000,500,40}; //中奖权值 
	public static int looptime = 100;//抽奖次数
	public static void main(String[] args) {
	 GetIndex getindex = new GetIndex();
	 
	 for (int j = 0;j<looptime;j++) {
		getindex.index = 0;
		getindex.weightAdder = 0;
		getindex.ran = new Random();
		getindex.weights = new int[map.length];
		//生成权限加法器数组，保证新生成数据值有序递增
		for(int w : map ) {
			getindex.weights[getindex.index++] = (getindex.weightAdder = getindex.weightAdder + w);
			
		}
		/*
		 * for(int w : weights) { System.out.println("数组："+w); }
		 */
		getindex.max = getindex.weights[getindex.weights.length-1]; //获取权限加法器数组最大值
		getindex.random = getindex.ran.nextInt(getindex.max)+1; //生成随机数
		getindex.dex = Arrays.binarySearch(getindex.weights, getindex.random);//重要：获取该数组的一个下标即为中奖值
		System.out.println("随机数："+getindex.random);
		System.out.println("Dex: "+getindex.dex);
		//计算dex时数组被加1，所以在此减一
		if(getindex.dex < 0) {
			getindex.dex = -1 - getindex.dex;
		}
		System.out.println("Result: "+getindex.dex+" 加法器数组数据："+getindex.weights[getindex.dex]+" 选中号："+map[getindex.dex]);
		if(getindex.dex == 4 || getindex.dex == 0 || getindex.dex == 3) { //假设第一位与第五位中奖
			getindex.record.add("中奖号："+map[getindex.dex]);
		}
	 }
	  for(String rec: getindex.record) {
		  System.out.println(rec );
	  }
	  String odds = df.format((float)getindex.record.size()/map.length);
	  System.out.println("中奖率: "+ odds );
	 
	}
}
以上是抽奖过程中的主要逻辑，其核心就是利用binarySearch函数在随机搜索值中找到一个搜索数组的一个下标，根据该下标定位到具体的奖品信息。