java.util.EnumMap.containsKey(Object key)%uA0方法确定如果此映射包含指定键的映射关系。
声明
以下是java.util.EnumMap.containsKey()方法的声明
public boolean containsKey(Object key)
参数
-
key--%uA0其是否存在于此映射中的键
返回值
如果此映射包含指定键的映射此方法返回true。
异常
-
NA
例子
下面的示例演示java.util.EnumMap.containsKey()方法的用法。
package com.yiibai import java.util.EnumMap public class EnumMapDemo { // create an enum public enum Numbers { ONE, TWO, THREE, FOUR, FIVE } public static void main(String[] args) { EnumMap<Numbers, String> map = new EnumMap<Numbers, String>(Numbers.class) // associate values in map map.put(Numbers.ONE, "1") map.put(Numbers.TWO, "2") map.put(Numbers.THREE, "3") map.put(Numbers.FOUR, "4") // print the whole map System.out.println(map) // check if map contains a mapping at specified key boolean contains = map.containsKey(Numbers.ONE) // print the result System.out.println("Numbers.ONE has a mapping:" + contains) // check if map contains a mapping at another specified key contains = map.containsKey(Numbers.FIVE) // print the result System.out.println("Numbers.FIVE has a mapping:" + contains) } }
让我们来编译和运行上面的程序，这将产生以下结果：
{ONE=1, TWO=2, THREE=3, FOUR=4} Numbers.ONE has a mapping:true Numbers.FIVE has a mapping:false