Java 中的字典放()方法，带示例
原文:https://www . geesforgeks . org/dictionary-put-method-in-Java-with-examples/
字典的 put()方法用于将映射插入到字典中。这意味着特定的键和值可以映射到特定的字典中。
语法:
DICTIONARY.put(key, value)
参数:该方法取两个参数，都是字典的对象类型。
- 关键:这是指需要插入字典进行映射的关键元素。
- 值:这是指上述键将映射到的值。
返回值:方法返回键映射到的值。如果键没有映射到任何值，则返回空值。
以下程序用于说明 java.util.Dictionary.put()方法: 程序 1:
// Java code to illustrate the put() 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 values 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("Initial Dictionary is: " + dict);
// Inserting existing key along with new value
String returned_value = (String)dict.put(20, "All");
// Verifying the returned value
System.out.println("Returned value is: " + returned_value);
// Displaying the new table
System.out.println("New Dictionary is: " + dict);
}
}
Output:
Initial Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
Returned value is: Geeks
New Dictionary is: {10=Geeks, 20=All, 30=You, 15=4, 25=Welcomes}
程序 2:
// Java code to illustrate the put() 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 values 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("Initial Dictionary is: " + dict);
// Inserting existing key along with new value
String returned_value = (String)dict.put(50, "All");
// Verifying the returned value
System.out.println("Returned value is: " + returned_value);
// Displaying the new table
System.out.println("New Dictionary is: " + dict);
}
}
Output:
Initial Dictionary is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
Returned value is: null
New Dictionary is: {10=Geeks, 20=Geeks, 30=You, 50=All, 15=4, 25=Welcomes}
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