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

Properties类的getProperty(key，defaultValue)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，则它将返回defaultValue。

用法:

public String getProperty(String key, String defaultValue)

参数：此方法接受两个参数：

key：whose的映射将在此Properties对象中检查。
defaultValue：这是键的默认映射

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，则它将返回defaultValue。

以下示例程序旨在说明getProperty(key，defaultValue)方法：

程序1:

// Java program to demonstrate 
// getProperty(key, defaultValue) 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", 200)); 
  
        // Getting the value of Phone 
        System.out.println("Value of Phone:"
                           + properties 
                                 .getProperty("Phone", 200)); 
    } 
}

输出：

Properties:{Book=500, Mobile=5000, Pen=10, Clothes=400}
Value of Pen:10
Value of Phone:200

程序2:

// Java program to demonstrate 
// getProperty(key, defaultValue) 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, "200RS")); 
  
        // Getting the value of 5 
        System.out.println("Value of 5:"
                           + properties 
                                 .getProperty(5, "200RS")); 
    } 
}

输出：

Current Properties:{3=1000RS, 2=500RS, 1=100RS}
Value of 1:100RS
Value of 5:200RS

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