Java EnumMap keySet()

keySet() 获取EnumMap的所有key的Set集合。

1 语法

public Set<K> keySet()  

2 参数

无

3 返回值

返回EnumMap的所有key的Set集合。

4 EnumMap keySet()示例1

package com.yiidian;

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

public class Demo {

    // create an enum
    public enum Tutorial {
        CSS, Python, PHP, Java, Javascript
    };
    public static void main(String[] args) {
        //创建EnumMap
        EnumMap<Tutorial, String >  map =
                new EnumMap<Tutorial, String> (Tutorial.class);

        map.put(Tutorial.CSS, "1");
        map.put(Tutorial.Python, "2");
        map.put(Tutorial.PHP, "3");
        map.put(Tutorial.Java, "4");
        //输出Map
        System.out.println("Map: "+map);
        //获取所有key
        Set<Tutorial>  set = map.keySet();
        //输出Map
        System.out.println("KeySet: "+set);
    }
}

输出结果为：

Map: {CSS=1, Python=2, PHP=3, Java=4}
KeySet: [CSS, Python, PHP, Java]

5 EnumMap keySet()示例2

package com.yiidian;

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

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");
        //输出Map
        System.out.println("Map: "+map);
        //获取key
        Set<Days>  set = map.keySet();
        //输出Map
        System.out.println("KeySet: "+set);
    }
}

输出结果为：

Map: {Monday=1, Tuesday=2, Wednesday=3}
KeySet: [Monday, Tuesday, Wednesday]