Java Properties containsKey(value)用法及代碼示例

Properties類的containsKey(value)方法用於檢查此Properties對象是否包含此Key的任何映射(對於其中存在的任何鍵)。它將此值作為參數進行比較，並返回一個布爾值作為結果。

用法:

public Object containsKey(Object value)

參數：此方法接受參數值，該參數值是要在此屬性中搜索的鍵。

返回值：此方法返回一個布爾值，該布爾值說明此鍵是否存在於此Properties對象中的結果。

以下示例程序旨在說明containsKey(value)方法：

示例1:

// Java program to demonstrate 
// containsKey(value) method. 
  
import java.util.*; 
  
public class GFG { 
  
    // Main method 
    public static void main(String[] args) 
    { 
  
        // Create a properties and add some values 
        Properties properties = new Properties(); 
        properties.put("Pen", 10); 
        properties.put("Book", 500); 
        properties.put("Clothes", 400); 
        properties.put("Mobile", 5000); 
  
        // Print Properties details 
        System.out.println("Current Properties: "
                           + properties.toString()); 
  
        // Check if Pen is present or not 
        // using containsKey() 
        System.out.println("Is Pen present: "
                           + properties.containsKey("Pen")); 
    } 
}

輸出：

Current Properties: {Book=500, Mobile=5000, Pen=10, Clothes=400}
Is Pen present: true

示例2:

// Java program to demonstrate 
// containsKey(value) method. 
  
import java.util.*; 
  
public class GFG { 
  
    // Main method 
    public static void main(String[] args) 
    { 
  
        // Create a properties and add some values 
        Properties properties = new Properties(); 
  
        properties.put(1, "100RS"); 
        properties.put(2, "500RS"); 
        properties.put(3, "1000RS"); 
  
        // print Properties details 
        System.out.println("Current Properties: "
                           + properties.toString()); 
  
        // Check if 5 is present or not 
        // using containsKey() 
        System.out.println("Is 5 present: "
                           + properties.containsKey(5)); 
    } 
}

輸出：

Current Properties: {3=1000RS, 2=500RS, 1=100RS}
Is 5 present: false

參考：https://docs.oracle.com/javase/9/docs/api/java/util/Properties.html#containsKey-java.lang.Object-

相關用法

注：本文由純淨天空篩選整理自Kirti_Mangal大神的英文原創作品 Properties containsKey(value) 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。