Java EnumMap containsKey()

containsKey() 方法用于判断EnumMap中是否存在指定的key。如果EnumMap中包含指定key的映射，则此方法返回true。

1 语法

public boolean containsKey(Object key)  

2 参数

key：需要判断的key。

3 返回值

如果EnumMap中包含指定key的映射，则此方法返回true。

4 EnumMap containsKey()示例1

package com.yiidian;

/**
 * 一点教程网： http://www.aoinnfy.com
 */
/**
 * Java EnumMap.containsKey的例子
 */
import java.util.EnumMap;

public class Demo {

    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("Java教程在EnumMap么？: "+contains);
        contains = map.containsKey(Tutorial. PHP);
        System.out.println("PHP教程在EnumMap么: "+contains);
    }
}

输出结果为：

{Java=1, Python=2, PHP=3, Android=4, AngularJS=5}
Java教程在EnumMap么？: true
PHP教程在EnumMap么: true

5 EnumMap containsKey()示例2

package com.yiidian;

/**
 * 一点教程网： http://www.aoinnfy.com
 */
/**
 * Java EnumMap.containsKey的例子
 */
import java.util.EnumMap;

public class Demo {

    //创建枚举
    public enum Days {
        Monday, Tuesday, Wednesday, Thursday
    };
    public static void main(String[] args) {
        //创建EnumMap
        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在Map中么？: "+contains);
        contains = map.containsKey(Days. Thursday);
        System.out.println("Days.Thursday在Map中么？: "+contains);
    }
}

输出结果为：

{Monday=1, Tuesday=2, Wednesday=3, Thursday=4}
Days.Tuesday在Map中么？: true
Days.Thursday在Map中么？: true