入学测试的一道题，求大神帮忙解决。 - 黑马程序员技术交流社区

public static void main(String[] args) {
String string = "abcdekka27qoq";
HashMap<String, Integer> map = count(string);
System.out.println(map);
TreeMap<String, Integer> treeMap = sortByValue(map);
System.out.println(treeMap);
}
private static HashMap<String, Integer> count(String string) {
String[] strings = string.split("");
HashMap<String, Integer> map = new HashMap<String, Integer>();
for (String s : strings) {
map.put(s, map.containsKey(s)?map.get(s)+1:1);
}
return map;
}
private static TreeMap<String, Integer> sortByValue(
final HashMap<String, Integer> map) {
TreeMap<String, Integer> treeMap = new TreeMap<String, Integer>(
new Comparator<String>() {
public int compare(String o1, String o2) {
Integer i1 = map.get(o1);
Integer i2 = map.get(o2);
if (!i1.equals(i2))
return i2.compareTo(i1);
return o1.compareTo(o2);
}
});
treeMap.putAll(map);
return treeMap;
}

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package itheima;
import java.util.*;
class MyComparator implements Comparator //定义比较器
{
Map tr;
public MyComparator(Map map)
{
this.tr=map;
}
public int compare(Object o1,Object o2)
{
Character c1=(Character)o1;
Character c2=(Character)o2;
Integer i1=(Integer)tr.get(o1);
Integer i2=(Integer)tr.get(o2);
int num=i2.compareTo(i1);
if(num==0)
return c1.compareTo(c2);
return num;
}
}
public class Test1 {
public static void sop(Object obj)
{
System.out.println(obj);
}
public static String filter(String str) //定义过滤输入字符串的方法，去掉除字母外的字符，返回输入的字母字符串
{
StringBuffer a = new StringBuffer();
char[] ch = str.toCharArray();
for(char c:ch)
{
if(c>='a'&&c<='z')
a.append(c);
}
return a.toString();
}
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
String input = scan.nextLine();
String str = filter(input);
sop(charCount(str));
}
public static String charCount(String st){
char[] ch = st.toCharArray();
StringBuffer sb = new StringBuffer();
Map<Character,Integer> mp = new HashMap<Character,Integer>();
for(char c:ch){
Integer count = mp.get(c);
if(count==null)
mp.put(c, 1);
else{
count++;
mp.put(c, count);
}
}
MyComparator myC=new MyComparator(mp);
TreeMap<Character,Integer> tm=new TreeMap<Character,Integer>(myC);
tm.putAll(mp);
Set<Character> keyset = tm.keySet(); //调用KeySet方法遍历集合tm
Iterator<Character> it = keyset.iterator();
while(it.hasNext()){
Character key = it.next();
Integer value = tm.get(key);
sb.append(key+"("+value+")");
}
return sb.toString();
}
}

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