Java教程

Java Collections syncNavigableMap()

Java集合类的 synchronizedNavigableMap()方法用于获取同步(线程安全)的可导航地图

语法

下面是 synchronizedNavigableMap()方法的声明:
public static <K,V> NavigableMap<K,V> synchronizedNavigableMap(NavigableMap<K,V> m)

参数

参数 说明 必需/可选
m 这是可导航地图,将被包装在同步的可导航地图中。 必需

返回

synchronizedNavigableMap()方法返回指定导航地图的同步视图。

异常

NA

兼容版本

Java 1.8及更高版本

示例1

import java.util.*;
public class CollectionsSynchronizedNavigableMapExample1 {
    public static void main(String[] args) {
        NavigableMap<String, String> map = new TreeMap<String, String>();
        map.put("3", "Java");
        map.put("4", "lidihuo");
        map.put("2", "Facebook");
        map.put("1", "Google");
        Map<String, String> synmap = Collections.synchronizedNavigableMap</span>(map);
        System.out.println("Synchronized navigable map is :" + synmap);              
          }
}
输出:
Synchronized navigable map is :{1=Google, 2=Facebook, 3=Java, 4=lidihuo}

示例2

import java.util.*;
public class CollectionsSynchronizedNavigableMapExample2 {
    public static void main(String[] args) {
        NavigableMap<Integer, Integer> map = new TreeMap<>();
        map.put(1, 1001);
        map.put(2, 1002);
        map.put(3, 1003);
        map.put(4, 1004);
        map.put(5, 1005);
        System.out.println("Map before synchronized navigable map: " + map);
        Map<Integer, Integer> synmap = Collections.synchronizedNavigableMap</span>(map);   
         map.remove(4, 1004);
         System.out.println("Synchronized navigable map after remove(4, 1004):" + synmap);
         }
}
输出:
Map before synchronized map: {1=1001, 2=1002, 3=1003, 4=1004, 5=1005}
Synchronized map after remove(4, 1004):{1=1001, 2=1002, 3=1003, 5=1005}

示例3

import java.util.Collections;
import java.util.NavigableMap;
import java.util.TreeMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
public class CollectionsSynchronizedNavigableMapExample3 {
    private static AtomicInteger counter = new AtomicInteger();
    public static void main(String[] args) throws InterruptedException {
        NavigableMap<Integer, Integer> m = new TreeMap<>();
        NavigableMap<Integer, Integer> map = Collections.synchronizedNavigableMap</span>(m);
        final ExecutorService e = Executors.newFixedThreadPool(10);
        for (int i = 0; i < 10; i++) {
            e.execute(() -> map.put(counter.incrementAndGet(),
                    (int) (Math.random() * 100)));
        }
        e.shutdown();
        e.awaitTermination(1000, TimeUnit.SECONDS);
        System.out.println(map.size());//should be 10
    }
}
输出:
10

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