哈希表类containsValue()方法 (Hashtable Class containsValue() method)

• containsValue() method is available in java.util package.

  containsValue()方法在java.util包中可用。

• containsValue() method is used to check whether this table Hashtable associated one or more keys to the given value element (val_ele).

  containsValue()方法用于检查此表Hashtable是否将一个或多个键关联到给定值元素(val_ele)。

• containsValue() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  containsValue()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• containsValue() method may throw an exception at the time of checking the key elements associated with the given value element (val_ele).

  在检查与给定值元素(val_ele)相关的关键元素时， containsValue()方法可能会引发异常。

  NullPointerException: This exception may throw when the given parameter is null exists.

  NullPointerException ：当给定参数为null时，可能引发此异常。

Syntax:

句法：

    public boolean containsValue(Object val_ele);

Parameter(s):

参数：

• Object val_ele – represents the value element (val_ele) is to be checked.

  对象val_ele –表示要检查的值元素(val_ele)。

Return value:

返回值：

The return type of the method is boolean,

方法的返回类型为boolean 。

• It returns true when at least one keys associated with the given value element (val_ele).

  当至少有一个与给定值元素(val_ele)相关联的键时，它返回true 。

• It returns false, when none keys associated with the given value element (val_ele).

  当没有与给定值元素(val_ele)关联的键时，它返回false 。

Example:

例：

// Java program to demonstrate the example 
// of boolean containsValue(Object val_ele) 
// method of Hashtable 
import java.util.*;
public class ContainsValueOfHashtable {
public static void main(String[] args) {
//Instantiate a hashtable object  
Hashtable ht = new Hashtable();
// By using put() method is to
// add the linked values in an Hashtable
ht.put(10, "C");
ht.put(20, "C++");
ht.put(30, "JAVA");
ht.put(40, "PHP");
ht.put(50, "SFDC");
// Display Hashtable
System.out.println("Hashtable: " + ht);
// By using containsValue() method is to
// check whether the given value element
// atleast holds one key element or not
// in this Hashtable
boolean status = ht.containsValue("JAVA");
// Display Status
System.out.println("ht.containsValue(JAVA): " + status);
}
}

Output

输出量

Hashtable: {10=C, 20=C++, 30=JAVA, 40=PHP, 50=SFDC}
ht.containsValue(JAVA): true

翻译自: https://www.includehelp.com/java/hashtable-containsvalue-method-with-example.aspx