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  • java hashtable 数据统计,计数功能

    package test;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.Hashtable;
    import java.util.List;
    
    class Counter{
        int i = 1;
    
        @Override
        public String toString(){
            return Integer.toString(i);
        }
    }
    public class Statistics {
        public static void main(String[] args) {
            List counter = new ArrayList(Arrays.asList(1, 2, 3, 1, 3, "b", "aa", "b", "b"));
            Hashtable ht =new Hashtable();
            // 统计数组中每个元素出现的次数
            for (int i = 0; i < counter.size(); i++) {
                if(ht.containsKey(counter.get(i))){
                    ((Counter)ht.get(counter.get(i))).i++;
                }else{
                    ht.put(counter.get(i), new Counter());
                }
            }
    
            // 生成20个30以内的随机数统计出现频次
            for (int i = 0; i < 20; i++) {
                int r = (int)(Math.random() * 30);
                if(ht.containsKey(r)){
                    ((Counter)ht.get(r)).i++;
                }else{
                    ht.put(r, new Counter());
                }
            }
            System.out.println(ht);
        }
    }
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  • 原文地址:https://www.cnblogs.com/wanglg629/p/9354303.html
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