Java 中的 EnumMap put()方法
原文:https://www.geeksforgeeks.org/enummap-put-method-in-java/
Java 中的 Java.util.EnumMap.put( 键，值)方法用于关联指定的键值对。在这种情况下，如果重复这些值，旧的值将被替换。
语法:
Enum_Map.put(*key, value*)
使用的参数:该方法采用两个参数。
- 键–它是与值相关联的指定键。
- 值–它是与指定键相关联的值。
返回值:函数返回与指定键相关的旧值。
以下程序说明了 put( 键，value )的工作方法: 程序 1:
// Java program to demonstrate keySet()
import java.util.*;
// An enum of geeksforgeeks
public enum gfg {
Global_today,
India_today,
China
}
;
class Enum_demo {
public static void main(String[] args)
{
EnumMap<gfg, Integer> mp = new
EnumMap<gfg, Integer>(gfg.class);
// Values are associated
mp.put(gfg.Global_today, 799);
mp.put(gfg.India_today, 69);
// Display the initial map
System.out.println("The map is: " + mp);
// Stores the old value associated with the key
int prev_value = mp.put(gfg.India_today, 72);
// Prints the old value
System.out.println("Previous value: " + prev_value);
// Display the final map
System.out.println("The final map is: " + mp);
}
}
Output:
The map is: {Global_today=799, India_today=69}
Previous value: 69
The final map is: {Global_today=799, India_today=72}
程序 2:
// Java program to demonstrate the working of keySet()
import java.util.*;
// an enum of geeksforgeeks
// ranking globally and in india
public enum gfg {
Global_today,
India_today,
China_today
}
;
class Enum_demo {
public static void main(String[] args)
{
EnumMap<gfg, Integer> mp = new EnumMap<gfg, Integer>(gfg.class);
// Values are associated
mp.put(gfg.Global_today, 799);
mp.put(gfg.India_today, 69);
// Display the initial map
System.out.println("The map is: " + mp);
// Stores the old value associated with the key
int prev_value = mp.put(gfg.Global_today, 800);
// Prints the old value
System.out.println("Previous value: " + prev_value);
// Display the final map
System.out.println("The final map is: " + mp);
}
}
Output:
The map is: {Global_today=799, India_today=69}
Previous value: 799
The final map is: {Global_today=800, India_today=69}
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