java enummap

EnumMap類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()方法用于檢查此映射是否具有此枚舉映射的給定鍵元素( 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()方法是一個非靜態方法，只能由類對象訪問，如果嘗試使用類名訪問該方法，則會收到錯誤消息。

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

  在檢查鍵映射時， containsKey()方法不會引發異常。

Syntax:

句法：

    public boolean containsKey(Object key_ele);

Parameter(s):

參數：

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

  對象key_ele –表示要檢查其存在的關鍵元素(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.

此方法的返回類型為boolean ，當此枚舉映射具有給定鍵元素(key_ele)的任何值時，它返回true，否則返回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

輸出量

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

翻譯自: https://www.includehelp.com/java/enummap-containskey-method-with-example.aspx

java enummap