Java SimpleBindings containsKey()用法及代碼示例

如果支持此SimpleBindings對象的映射包含指定鍵的映射，則SimpleBindings類的containsKey()方法用於返回true。如果SimpleBindings對象包含此鍵，則該方法返回true，否則返回false。

用法:

public boolean containsKey(Object key)

參數：此方法僅接受一個參數key，這是要在此映射中進行測試的鍵。

返回值：如果此映射包含指定鍵的映射，則此方法返回true。

異常：此方法引發以下異常：

NullPointerException ：如果鍵為空
ClassCastException：如果鍵不是字符串
IllegalArgumentException：如果鍵為空String

Java程序來說明containsKey()方法的用法：

程序1:

// Java program to demonstrate containsKey() method 
  
import javax.script.SimpleBindings; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create simpleBindings object 
        SimpleBindings bindings = new SimpleBindings(); 
  
        // add some keys with values 
        bindings.put("key1", "value1"); 
        bindings.put("key2", "value2"); 
        bindings.put("key3", "value3"); 
  
        // check key2 is exists in bindings or not 
        boolean isKey2Exist = bindings.containsKey("key2"); 
  
        // print 
        System.out.println("Key2 exits:" + isKey2Exist); 
    } 
}

輸出：

Key2 exits:true

程序2:

// Java program to demonstrate containsKey() method 
  
import javax.script.SimpleBindings; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
  
        // create simpleBindings object 
        SimpleBindings asiaTeamList 
            = new SimpleBindings(); 
  
        // add team in asiaTeamList 
        asiaTeamList.put("team1", "India"); 
        asiaTeamList.put("team2", "Sri Lanka"); 
        asiaTeamList.put("team3", "Pakistan"); 
        asiaTeamList.put("team4", "Bangladesh"); 
  
        // check England exists in bindings or not 
        boolean isKey2Exist 
            = asiaTeamList.containsKey("England"); 
  
        // print 
        System.out.println("England exits in Asia Team:"
                           + isKey2Exist); 
    } 
}

輸出：

England exits in Asia Team:false

參考文獻： https://docs.oracle.com/javase/10/docs/api/javax/script/SimpleBindings.html#containsKey(java.lang.Object)

相關用法

注：本文由純淨天空篩選整理自AmanSingh2210大神的英文原創作品 SimpleBindings containsKey() method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。