Java EnumMap containsKey()
Java EnumMap类的
containsKey()方法用于检查此映射中是否存在指定的键或不。如果此映射包含指定键的映射，则此方法返回true。
语法
public boolean containsKey(Object key)
参数
key-要在此映射中进行测试的键
返回
如果此映射包含指定键的映射，则此方法返回true。
异常
NA
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) {
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
