java8 map排序
通过key排序
package test;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
public class SortByKeyExample {
public static void main(String[] argv) {
Map<String, Integer> unsortMap = new HashMap<>();
unsortMap.put("z", 10);
unsortMap.put("b", 5);
unsortMap.put("a", 6);
unsortMap.put("c", 20);
unsortMap.put("d", 1);
unsortMap.put("e", 7);
unsortMap.put("y", 8);
unsortMap.put("n", 99);
unsortMap.put("j", 50);
unsortMap.put("m", 2);
unsortMap.put("f", 9);
System.out.println("Original...");
System.out.println(unsortMap);
Map<String, Integer> result = new LinkedHashMap<>();
//排序关键代码
unsortMap.entrySet().stream()
.sorted(Map.Entry.comparingByKey())
.forEachOrdered(x -> result.put(x.getKey(), x.getValue()));
System.out.println("Sorted...");
System.out.println(result);
}
}
运行结果：
Original...
{
a=6, b=5, c=20, d=1, e=7, f=9, y=8, z=10, j=50, m=2, n=99}
Sorted...
{
a=6, b=5, c=20, d=1, e=7, f=9, j=50, m=2, n=99, y=8, z=10}
Process finished with exit code 0
通过value排序
package test;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
public class SortByKeyExample {
public static void main(String[] argv) {
Map<String, Integer> unsortMap = new HashMap<>();
unsortMap.put("z", 10);
unsortMap.put("b", 5);
unsortMap.put("a", 6);
unsortMap.put("c", 20);
unsortMap.put("d", 1);
unsortMap.put("e", 7);
unsortMap.put("y", 8);
unsortMap.put("n", 99);
unsortMap.put("j", 50);
unsortMap.put("m", 2);
unsortMap.put("f", 9);
System.out.println("Original...");
System.out.println(unsortMap);
Map<String, Integer> result = new LinkedHashMap<>();
//sort by key, a,b,c..., and put it into the "result" map
//排序关键代码
unsortMap.entrySet().stream()
.sorted(Map.Entry.comparingByKey())
.forEachOrdered(x -> result.put(x.getKey(), x.getValue()));
System.out.println("Sorted...");
System.out.println(result);
}
}
运行结果：
Original...
{
a=6, b=5, c=20, d=1, e=7, f=9, y=8, z=10, j=50, m=2, n=99}
Sorted...
{
n=99, j=50, c=20, z=10, f=9, y=8, e=7, a=6, b=5, m=2, d=1}
Process finished with exit code 0