Java实现随机抽奖的三种方法

import java.util.Random;  
  
public class LotteryFromArray {  
    public static void main(String[] args) {  
        String[] candidates = {"Alice", "Bob", "Charlie", "David", "Eva"};  
        Random random = new Random();  
          
        // 生成一个0到candidates.length-1之间的随机数  
        int index = random.nextInt(candidates.length);  
          
        // 输出中奖者  
        System.out.println("中奖者是：" + candidates[index]);  
    }  
}

import java.util.ArrayList;  
import java.util.List;  
import java.util.Random;  
  
public class LotteryFromList {  
    public static void main(String[] args) {  
        List<String> candidates = new ArrayList<>();  
        candidates.add("Alice");  
        candidates.add("Bob");  
        candidates.add("Charlie");  
        candidates.add("David");  
        candidates.add("Eva");  
          
        Random random = new Random();  
          
        // 生成一个0到candidates.size()-1之间的随机数  
        int index = random.nextInt(candidates.size());  
          
        // 输出中奖者  
        System.out.println("中奖者是：" + candidates.get(index));  
    }  
}

import java.util.ArrayList;  
import java.util.List;  
import java.util.Random;  
  
public class LotteryWithWeights {  
  
    static class Candidate {  
        String name;  
        int weight; // 权重  
  
        public Candidate(String name, int weight) {  
            this.name = name;  
            this.weight = weight;  
        }  
    }  
  
    public static void main(String[] args) {  
        List<Candidate> candidates = new ArrayList<>();  
        candidates.add(new Candidate("Alice", 1));  
        candidates.add(new Candidate("Bob", 3));  
        candidates.add(new Candidate("Charlie", 1));  
        candidates.add(new Candidate("David", 2));  
        candidates.add(new Candidate("Eva", 3));  
  
        Random random = new Random();  
        int totalWeight = 0;  
        for (Candidate candidate : candidates) {  
            totalWeight += candidate.weight;  
        }  
  
        int target = random.nextInt(totalWeight) + 1;  
        int sum = 0;  
        for (Candidate candidate : candidates) {  
            sum += candidate.weight;  
            if (sum >= target) {  
                System.out.println("中奖者是：" + candidate.name);  
                break;  
            }  
        }  
    }  
}