1 Map中查看是否包含某个key用containsKey、查看是否包含某个值用containsValue 直接上代码 publicvoidtestContains(){ System.out.println(""); System.out.println("查看是否包含某学生,请输入ID:"); Scanner console=newScanner(System.in); String id=console.next();if(students.containsKey(id)){ Student st...
JAVA中 Map之 containsKey、 containsValue 仅供个人学习记录,侵删 1 Map中查看是否包含某个key用containsKey、查看是否包含某个值用containsValue 直接上代码 public void testContains(){ System.out.println(""); System.out.println("查看是否包含某学生,请输入ID:"); Scanner console = new Scanner(System.in...
returns true if and only if this map contains at least one mapping to a value v such that (value==null ? v==null : value.equals(v)). This operation will probably require time linear in the map size for most implementations of the Map interface. ...
注:跟List中的Contains()方法一样,Map中的ContainsValue()方法也需要调用某个Value值的equals()方法,去和参数对象进行比较,如果匹配成功,返回结果为true,说明在Map中的Value值确实包含参数对象。因此,需要重写Student类的equals()方法。 Student类: packagecom.test.collection;importjava.util.HashSet;importjava.util...
而Value是Student类型的,equals()是直接用==实现的,==比较的是对象的引用地址,当然返回结果是false(参考equals()与==的区别与实际应用)。所以,要在Map中通过学生的名字判断是否包含该学生,需要重写equals()方法。 在Student.java中重写equals()方法: @Overridepublicboolean equals(Object obj) {if(this== obj)...
The Java HashMap containsValue() method checks if the specified value is present in one or more mappings of the hashmap. In this tutorial, we will learn about the HashMap containsValue() method with the help of examples.
而Value是Student类型的,equals()是直接用==实现的,==比较的是对象的引用地址,当然返回结果是false(参考equals()与==的区别与实际应用)。所以,要在Map中通过学生的名字判断是否包含该学生,需要重写equals()方法。 在Student.java中重写equals()方法: @Override...
import java.util.HashMap; public class Main { public static void main(String[] args) { HashMap<String, String> capitalCities = new HashMap<String, String>(); capitalCities.put("England", "London"); capitalCities.put("Germany", "Berlin"); capitalCities.put("Norway", "Oslo"); capital...
Java.Time Java.Time.Chrono Java.Time.Format Java.Time.Temporal Java.Time.Zone Java.Util Java.Util AbstractCollection AbstractList AbstractMap AbstractMap 构造函数 属性 方法 Clear ContainsKey ContainsValue EntrySet Get KeySet Put PutAll Remove Size ...
More formally, returns true if and only if this map contains at least one mapping to a value v such that Objects.equals(value, v). This operation will probably require time linear in the map size for most implementations of the Map interface. Java documentation for java.util.Map.contains...