Java 中的字典 get()方法，带示例
原文:https://www . geesforgeks . org/dictionary-get-method-in-Java-with-examples/
Dictionary 类的 get()方法用于检索或获取由参数中提到的特定键映射的值。当字典不包含键的这种映射时，它返回空值。
语法:
DICTIONARY.get(Object key_element)
参数:该方法取一个对象类型的参数 key_element ，指的是应该取其关联值的键。
返回值:该方法返回与参数中 key_element 关联的值。
以下程序用于说明 java.util.Dictionary.get()方法: 程序 1:
// Java code to illustrate the get() 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 the values into 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("Initial Dictionary is: " + dict);
// Getting the value of 25
System.out.println("The Value is: " + dict.get(25));
// Getting the value of 10
System.out.println("The Value is: " + dict.get(10));
}
}
Output:
Initial Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
The Value is: Welcomes
The Value is: Geeks
程序 2:
// Java code to illustrate the get() 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 the values into dictionary
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("Initial Dictionary is: "
+ dict);
// Getting the value of 25
System.out.println("The Value is: "
+ dict.get("Geeks"));
// Getting the value of 10
System.out.println("The Value is: "
+ dict.get(20));
}
}
Output:
Initial Dictionary is: {You=30, Welcomes=25, 4=15, Geeks=20}
The Value is: 20
The Value is: null
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