Java EnumMap containsKey() 方法

2024年11月8日 | 1 分钟阅读

Java EnumMap 类的 containsKey() 方法用于检查指定的键是否存在于此映射中。如果此映射包含指定键的映射，则此方法返回 true。

语法

参数

key - 要在此映射中测试其存在性的键

返回值

如果此映射包含指定键的映射，则此方法返回 true。

Exception

不适用

示例 1

import java.util.EnumMap;
public class EnumMapContainsKeyExample1 {
    public enum Tutorial {
    Java,Python, PHP,Android,AngularJS
    };
    public static void main(String[] args) {
    EnumMap<Tutorial, String> map =
          new EnumMap<Tutorial, String>(Tutorial.class);
    map.put(Tutorial.Java,"1");
    map.put(Tutorial.Python,"2");
    map.put(Tutorial.PHP,"3");
    map.put(Tutorial.Android,"4");
    map.put(Tutorial.AngularJS,"5");
    System.out.println(map);
    boolean contains = map.containsKey(Tutorial.Java);
    System.out.println("Tutorial.Java has a mapping: "+contains);
    contains = map.containsKey(Tutorial. PHP);
    System.out.println("Tutorial.PHP has a mapping: "+contains);
   }
}

输出

{Java=1, Python=2, PHP=3, Android=4, AngularJS=5}
Tutorial.Java has a mapping:  true
Tutorial.PHP has a mapping:  true

示例 2

import java.util.EnumMap;
public class EnumMapContainsKeyExample2 {
    // create an enum  
   public enum Days {  
   Monday, Tuesday, Wednesday, Thursday  
   };  
   public static void main(String[] args) {  
   //create and populate enum map  
   EnumMap<Days, String> map = new EnumMap<Days, String>(Days.class);  

   map.put(Days.Monday,"1");  
   map.put(Days.Tuesday,"2");  
   map.put(Days.Wednesday,"3");  
   map.put(Days.Thursday,"4");  
   System.out.println(map);
   boolean contains = map.containsKey(Days.Tuesday);
   System.out.println("Days.Tuesday has a mapping: "+contains);
   contains = map.containsKey(Days. Thursday);
   System.out.println("Days.Thursday has a mapping: "+contains);
  }
}

输出

{Monday=1, Tuesday=2, Wednesday=3, Thursday=4}
Days.Tuesday has a mapping: true
Days.Thursday has a mapping: true

下一主题Java-enummap-containsvalue-method

Java EnumMap containsKey() 方法

语法

参数

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Exception

示例 1

示例 2

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Java EnumMap containsKey() 方法

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示例 1

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