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| import java.util.Set; import java.util.TreeMap;
 
 //获取一个字符串"sdfaswefavzvezvrzzvrszzcewe"中字符的个数,并以a(1)b(2)...的形式输出。
 public class TreeMapSortDemo {
 public static void main(String[] args) {
 TreeMap<Character, Integer> tm = new TreeMap<Character, Integer>();
 String s ="sdfaswefavzvezvrzzvrszzcewe";
 char[] ch = s.toCharArray();
 for (char c : ch) {
 Integer i = tm.get(c);
 if(i!=null){
 i++;
 tm.put(c,i);
 }else{
 tm.put(c, 1);
 }
 }
 StringBuilder sb = new StringBuilder();
 Set<Character> keySet = tm.keySet();
 for (Character key : keySet) {
 Integer i =tm.get(key);
 sb.append(key+"("+i+")");
 }
 System.out.println(sb);
 }
 
 }
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