Java EnumMap size()

size() 获取EnumMap的元素个数。此方法返回一个整数。

1 语法

public int size()  

2 参数

无

3 返回值

返回EnumMap的元素个数。

4 EnumMap size()示例1

package com.yiidian;

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

public class Demo {

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

        map.put(Tutorial.Java, "1");
        map.put(Tutorial.CSS, "2");
        map.put(Tutorial.Python, "3");
        map.put(Tutorial.Android, "4");
        //输出Map
        System.out.println("Map: "+map);
        //输出Map的元素个数
        System.out.println("Number of mappings: "+map.size());
        //添加元素
        map.put(Tutorial.Javascript, "5");
        //输出Map
        System.out.println("Map: "+map);
        //输出Map的元素个数
        System.out.println("Number of mappings: "+map.size());
    }
}

输出结果为：

Map: {Java=1, CSS=2, Python=3, Android=4}
Number of mappings: 4
Map: {Java=1, CSS=2, Python=3, Android=4, Javascript=5}
Number of mappings: 5

5 EnumMap size()示例2

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java EnumMap.size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) {
        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);
        //输出Map的元素个数
        System.out.println("Number of mappings: "+map.size());
        //添加元素
        map.put(Days.Thursday, "4");
        //输出Map
        System.out.println("Map: "+map);
        //输出Map的元素个数
        System.out.println("Number of mappings: "+map.size());
    }
}

输出结果为：

Map: {Monday=1, Tuesday=2, Wednesday=3}
Number of mappings: 3
Map: {Monday=1, Tuesday=2, Wednesday=3, Thursday=4}
Number of mappings: 4