Java.util.EnumMap.containsKey() Java.util.EnumMap.clone() Java.util.EnumMap.containsValue() 描述 所述java.util.EnumMap.containsKey(Object key)方法确定是否此映射包含指定键的映射。 声明 以下是java.util.EnumMap.containsKey()方法的声明 public boolean containsKey(Object key) 参数 key - 要测试其在此映射中的存在的键 返回值 如果此映射包含指定键的映射,则此方法返回true。 异常 NA 实例 以下示例显示了java.util.EnumMap.containsKey()方法的用法。 package com.tutorialspoint; 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); } } 让我们编译并运行上面的程序,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 Java.util.EnumMap.clone() Java.util.EnumMap.containsValue()