TreeMap

1. 

    

    

2. 

    

    

3. 练习2;

    

    

4. 代码实现：

   import java.util.TreeMap;
   import java.util.function.BiConsumer;
   
   public class treemap练习2 {
       public static void main(String[] args) {
           String s="aababaccs";
           TreeMap<Character,Integer> treeMap=new TreeMap<>();
           for (int i = 0; i <s.length() ; i++) {
               char c = s.charAt(i);
               if (treeMap.containsKey(c)){
                   int count =treeMap.get(c);
                   count++;
                   treeMap.put(c,count);
   
               }else {
                   treeMap.put(c,1);
               }
   
           }
           //进行字符串的拼接：
           StringBuilder stringBuilder=new StringBuilder();
           treeMap.forEach(new BiConsumer<Character, Integer>() {
               @Override
               public void accept(Character key, Integer value) {
                stringBuilder.append(key).append("(").append(value).append(")");
               }
           });
           System.out.println(stringBuilder);
       }
   }

5. 小结：