Java Properties getProperty(key)用法及代码示例

Properties类的getProperty(key)方法用于获取映射到此键的值，该键作为参数传递到此Properties对象中。如果存在，此方法将获取与此键对应的值，然后将其返回。如果没有这样的映射，则返回null。

用法:

public Object getProperty(String key)

参数：此方法接受参数键，该参数键的映射将在此Properties对象中检查。

返回值：如果存在，此方法将返回与此键对应的取值。如果没有这样的映射，则返回null。

以下示例程序旨在说明getProperty(key)方法：

示例1:

// Java program to demonstrate 
// getProperty(key) 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("Properties: "
                           + properties 
                                 .toString()); 
  
        // Getting the value of Pen 
        System.out.println("Value of Pen: "
                           + properties 
                                 .getProperty("Pen")); 
  
        // Getting the value of Phone 
        System.out.println("Value of Phone: "
                           + properties 
                                 .getProperty("Phone")); 
    } 
}

输出：

Properties: {Book=500, Mobile=5000, Pen=10, Clothes=400}
Value of Pen: null
Value of Phone: null

示例2:

// Java program to demonstrate 
// getProperty(key) 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()); 
  
        // Getting the value of 1 
        System.out.println("Value of 1: "
                           + properties 
                                 .getProperty("1")); 
  
        // Getting the value of 5 
        System.out.println("Value of 5: "
                           + properties 
                                 .getProperty("5")); 
    } 
}

输出：

Current Properties: {3=1000RS, 2=500RS, 1=100RS}
Value of 1: null
Value of 5: null

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

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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 getProperty(key) 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。