Java Properties containsKey(value)用法及代码示例

Properties类的containsKey(value)方法用于检查此Properties对象是否包含此Key的任何映射(对于其中存在的任何键)。它将此值作为参数进行比较，并返回一个布尔值作为结果。

用法:

public Object containsKey(Object value)

参数：此方法接受参数值，该参数值是要在此属性中搜索的键。

返回值：此方法返回一个布尔值，该布尔值说明此键是否存在于此Properties对象中的结果。

以下示例程序旨在说明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")); 
    } 
}

输出：

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)); 
    } 
}

输出：

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

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

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注：本文由纯净天空筛选整理自Kirti_Mangal大神的英文原创作品 Properties containsKey(value) method in Java with Examples。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。