MAP集合排序

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//首先TreeMap,SortedMap排序性能高于HashMap

介绍map集合排序

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class MapPX {

/**
* @param args
*/
@SuppressWarnings("unchecked")
public static void main(String[] args) {
Map<String,Float> PXMap = new HashMap<String,Float>();//排序专用
PXMap.put("a1", 12f);
PXMap.put("a2", 1212f);
PXMap.put("a3", 122f);
PXMap.put("a4", 123f);
PXMap.put("a5", 112f);
System.out.println(PXMap);
List list = new ArrayList(PXMap.entrySet());
Collections.sort(list, new CompareSort());
System.out.println("s:"+list);
for(int i=0;i<list.size();i++)
{
Iterator it= list.iterator();
System.out.println(list.get(i));
}
}

}

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

//map集合比较转换类
public class CompareSort implements Comparator< Map.Entry<String, Float> > {

@SuppressWarnings("unchecked")
@Override
public int compare( Map.Entry<String, Float> o1, Map.Entry<String, Float> o2) {
Map.Entry<String,Float> map1=(Map.Entry<String,Float>)o1;
Map.Entry<String,Float> map2=(Map.Entry<String,Float>)o2;
return (int) (map1.getValue()- map2.getValue());
}

}

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