java enummap

EnumMap类containsKey()方法 (EnumMap Class containsKey() method)

• containsKey() method is available in java.util package.

  containsKey()方法在java.util包中可用。

• containsKey() method is used to check whether this map has values for the given key element (key_ele) of this enum map.

  containsKey()方法用于检查此映射是否具有此枚举映射的给定键元素( key_ele )的值。

• containsKey() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  containsKey()方法是一个非静态方法，只能由类对象访问，如果尝试使用类名访问该方法，则会收到错误消息。

• containsKey() method does not throw an exception at the time of checking key mappings.

  在检查键映射时， containsKey()方法不会引发异常。

Syntax:

句法：

    public boolean containsKey(Object key_ele);

Parameter(s):

参数：

• Object key_ele – represents the key element (key_ele) whose presence is to be checked.

  对象key_ele –表示要检查其存在的关键元素(key_ele)。

Return value:

返回值：

The return type of this method is boolean, it returns true when this enum map have any value for the given key element (key_ele) otherwise it returns false.

此方法的返回类型为boolean ，当此枚举映射具有给定键元素(key_ele)的任何值时，它返回true，否则返回false。

Example:

例：

// Java program to demonstrate the example
// of boolean containsKey(Object key_ele) method of EnumMap
import java.util.*;
public class ContainsKeyOfEnumMap {public enum Colors {RED,
BLUE,
PINK,
YELLOW
};
public static void main(String[] args) {// We are creating EnumMap object
EnumMap < Colors, String > em =
new EnumMap < Colors, String > (Colors.class);
// By using put() method is to
// add the linked values in an EnumMap
em.put(Colors.RED, "1");
em.put(Colors.BLUE, "2");
em.put(Colors.PINK, "3");
em.put(Colors.YELLOW, "4");
// Display EnumMap
System.out.println("EnumMap :" + em);
// By using containsKey() method isto
// check whether this EnumMap contains
// any value for the given key element
// in an EnumMap
boolean status = em.containsKey(Colors.PINK);
// Display status of EnumMap
System.out.println("em.containsKey(Colors.PINK): " + status);
}
}

Output

输出量

EnumMap :{RED=1, BLUE=2, PINK=3, YELLOW=4}
em.containsKey(Colors.PINK): true

翻译自: https://www.includehelp.com/java/enummap-containskey-method-with-example.aspx

java enummap