一个应该跟JDK版本有关的问题。 - 黑马程序员技术交流社区

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
public class Test4
{
public static void main(String[] args)
{
String str = "abadcdffbaeba";
Map<String,Long> result = new HashMap<String,Long>();
String[] s = str.split("");
for(String c : s) {
if("".equals(c)) continue;
if(result.get(c) != null) {
result.put(c, result.get(c)+1);
} else {
result.put(c,1L);
}
}
List<Map.Entry<String, Long>> list = new ArrayList<Map.Entry<String, Long>>(result.entrySet());
Collections.sort(list, new Comparator<Map.Entry<String, Long>>() {
@Override
public int compare(Entry<String, Long> o1, Entry<String, Long> o2) {
long i = o1.getValue() - o2.getValue();
if(i==0l) {
return o2.getValue().compareTo(o1.getValue())==0 ? 1 :0;
}
return i > 0l ? 1 : 0;
}
});
for(Map.Entry<String, Long> me : list) {
System.out.println(me.getKey() + ":" +me.getValue());
}
}
}

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