Java 中的 Collections synchronizedMap()方法，示例
原文:https://www . geesforgeks . org/collections-synchronized map-method-in-Java-with-examples/
java.util.Collections 类的 synchronizedMap() 方法用于返回由指定映射支持的同步(线程安全)映射。为了保证串行访问，通过返回的映射完成对后备映射的所有访问是至关重要的。
语法:
公共静态地图同步地图(地图米)
参数:该方法将地图作为参数“包裹”在同步地图中。
返回值:该方法返回指定地图的同步视图。
以下是说明 synchronizedMap() 方法的示例。
例 1:
// Java program to demonstrate
// synchronizedMap() method
// for <String, String> Value
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
// creating object of Map<String, String>
Map<String, String>
map = new HashMap<String, String>();
// populate the map
map.put("Value1", "20");
map.put("Value2", "30");
map.put("Value3", "40");
// printing the Collection
System.out.println("Map : " + map);
// create a synchronized map
Map<String, String>
synmap = Collections.synchronizedMap(map);
// printing the Collection
System.out.println("Synchronized map is : "
+ synmap);
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
Map : {Value3=40, Value1=20, Value2=30}
Synchronized map is : {Value3=40, Value1=20, Value2=30}
*例 2:*
// Java program to demonstrate
// synchronizedMap() method
// for <String, Boolean> Value
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
// creating object of Map<String, Boolean>
Map<String, Boolean>
map = new HashMap<String, Boolean>();
// populate the map
map.put("Bramha", true);
map.put("Vishnu", true);
map.put("Mahesh", true);
// printing the Collection
System.out.println("Map : " + map);
// create a synchronized map
Map<String, Boolean>
synmap = Collections.synchronizedMap(map);
// printing the Collection
System.out.println("Synchronized map is : "
+ synmap);
}
catch (IllegalArgumentException e) {
System.out.println("Exception thrown : " + e);
}
}
}
Output:
Map : {Bramha=true, Vishnu=true, Mahesh=true}
Synchronized map is : {Bramha=true, Vishnu=true, Mahesh=true}
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