Java中的WeakHashMap entrySet()方法
Java中的Java .util.WeakHashMap.entrySet() 方法用于从地图中包含的相同元素创建一个集合。它基本上返回弱哈希映射的集合视图,或者我们可以创建一个新集合并将映射元素存储到其中。
句法:
weak_hash_map.entrySet()
参数:该方法不带任何参数。
返回值:该方法返回一个与地图具有相同元素的集合。
下面的程序说明了Java.util.WeakHashMap.entrySet() 方法:
程序 1:将字符串值映射到整数键。
// Java code to illustrate the entrySet() method
import java.util.*;
public class Weak_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty WeakHashMap
Map weak_hash = new WeakHashMap();
// Mapping string values to int keys
weak_hash.put(10, "Geeks");
weak_hash.put(15, "4");
weak_hash.put(20, "Geeks");
weak_hash.put(25, "Welcomes");
weak_hash.put(30, "You");
// Displaying the WeakHashMap
System.out.println("Initial Mappings are: " + weak_hash);
// Using entrySet() to get the set view
System.out.println("The set is: " + weak_hash.entrySet());
}
}
输出:
Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks}
The set is: [30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks]
程序 2:将整数值映射到字符串键。
// Java code to illustrate the entrySet() method
import java.util.*;
public class Weak_Hash_Map_Demo {
public static void main(String[] args)
{
// Creating an empty WeakHashMap
Map weak_hash = new WeakHashMap();
// Mapping int values to string keys
weak_hash.put("Geeks", 10);
weak_hash.put("4", 15);
weak_hash.put("Geeks", 20);
weak_hash.put("Welcomes", 25);
weak_hash.put("You", 30);
// Displaying the WeakHashMap
System.out.println("Initial Mappings are: " + weak_hash);
// Using entrySet() to get the set view
System.out.println("The set is: " + weak_hash.entrySet());
}
}
输出:
Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
The set is: [Welcomes=25, 4=15, You=30, Geeks=20]
注意:可以对任何类型的映射执行相同的操作,这些映射具有不同数据类型的变化和组合。