java-map按照value值来比较大小并且返回最终结果
目录
java map按照value值来比较大小并且返回最终结果
原文:
源代码下载地址:
package com.zuidaima.util;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
public class ValueComparator implements Comparator<Long> {
Map<Long, Double> base;
public ValueComparator(Map<Long, Double> base) {
this.base = base;
}
public int compare(Long a, Long b) {
if (base.get(a).doubleValue() >= base.get(b).doubleValue()) {
return -1;
} else {
return 1;
}
}
public static <K, V extends Comparable<V>> Map<K, V> sortByValues(
final Map<K, V> map) {
Comparator<K> valueComparator = new Comparator<K>() {
public int compare(K k1, K k2) {
int compare = map.get(k2).compareTo(map.get(k1));
if (compare == 0)
return 1;
else
return compare;
}
};
Map<K, V> sortedByValues = new TreeMap<K, V>(valueComparator);
sortedByValues.putAll(map);
return sortedByValues;
}
public static void main(String[] args) {
HashMap<Long, Double> map = new HashMap<Long, Double>();
map.put(1l, 99.5);
map.put(2l, 67.2);
map.put(3l, 67.5);
map.put(4l, 67.6);
ValueComparator bvc = new ValueComparator(map);
TreeMap<Long, Double> sorted_map = new TreeMap<Long, Double>(bvc);
System.out.println("unsorted map: " + map);
sorted_map.putAll(map);
System.out.println("results: " + sorted_map);
Map<Long, Double> sorted_map2 = sortByValues(map);
System.out.println("results2: " + sorted_map2);
}
}
输出结果:
unsorted map: {1=99.5, 2=67.2, 3=67.5, 4=67.6}
results: {1=99.5, 4=67.6, 3=67.5, 2=67.2}
results2: {1=99.5, 4=67.6, 3=67.5, 2=67.2}
通过key比较大小的原理类似,大家改写下就好了。enjoy it。