Java 中的字典键()方法，带示例
原文:https://www . geesforgeks . org/dictionary-key-method-in-Java-with-examples/
Java 中 Dictionary 类的 keys()方法用于获取字典中存在的键的枚举。
语法:
Enumeration enu = DICTIONARY.keys()
参数:该方法不取任何参数。
返回值:该方法返回字典键的枚举。
下面的程序用来说明 java.util.Dictionary.keys()方法的工作: 程序 1:
// Java code to illustrate the keys() method
import java.util.*;
public class Dictionary_Demo {
public static void main(String[] args)
{
// Creating an empty Dictionary
Dictionary<Integer, String> dict
= new Hashtable<Integer, String>();
// Inserting elements into the Dictionary
dict.put(10, "Geeks");
dict.put(15, "4");
dict.put(20, "Geeks");
dict.put(25, "Welcomes");
dict.put(30, "You");
// Displaying the Dictionary
System.out.println("The Dictionary is: " + dict);
// Creating an empty enumeration to store
Enumeration enu = dict.keys();
System.out.println("The enumeration of keys are:");
// Displaying the Enumeration
while (enu.hasMoreElements()) {
System.out.println(enu.nextElement());
}
}
}
Output:
The Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
The enumeration of keys are:
10
20
30
15
25
程序 2:
// Java code to illustrate the keys() method
import java.util.*;
public class Dictionary_Demo {
public static void main(String[] args)
{
// Creating an empty Dictionary
Dictionary<String, Integer> dict
= new Hashtable<String, Integer>();
// Inserting elements into the table
dict.put("Geeks", 10);
dict.put("4", 15);
dict.put("Geeks", 20);
dict.put("Welcomes", 25);
dict.put("You", 30);
// Displaying the Dictionary
System.out.println("The Dictionary is: " + dict);
// Creating an empty enumeration to store
Enumeration enu = dict.keys();
System.out.println("The enumeration of keys are:");
// Displaying the Enumeration
while (enu.hasMoreElements()) {
System.out.println(enu.nextElement());
}
}
}
Output:
The Dictionary is: {You=30, Welcomes=25, 4=15, Geeks=20}
The enumeration of keys are:
You
Welcomes
4
Geeks
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