哈希表類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()方法用于檢查此表Hashtable是否將一個或多個鍵關聯到給定值元素(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()方法是一個非靜態方法，只能通過類對象訪問，如果嘗試使用類名稱訪問該方法，則會收到錯誤消息。

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

  在檢查與給定值元素(val_ele)相關的關鍵元素時， containsValue()方法可能會引發異常。

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

  NullPointerException ：當給定參數為null時，可能引發此異常。

Syntax:

句法：

    public boolean containsValue(Object val_ele);

Parameter(s):

參數：

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

  對象val_ele –表示要檢查的值元素(val_ele)。

Return value:

返回值：

The return type of the method is boolean,

方法的返回類型為boolean 。

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

  當至少有一個與給定值元素(val_ele)相關聯的鍵時，它返回true 。

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

  當沒有與給定值元素(val_ele)關聯的鍵時，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

輸出量

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

翻譯自: https://www.includehelp.com/java/hashtable-containsvalue-method-with-example.aspx