Java中的属性 get(key) 方法和示例

Properties 类的get(key)方法用于在此 Properties 对象中获取映射到此键的值，作为参数传递。此方法将获取此键的对应值（如果存在）并将其返回。如果没有这样的映射，则返回 null。

句法：

public Object get(Object key)

参数：此方法接受要在此 Properties 对象中检查其映射的参数键。

返回：此方法返回与此键对应的提取值（如果存在）。如果没有这样的映射，则返回 null。

下面的程序说明了 get(key) 方法：

方案一：

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

输出：

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

方案二：

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

输出：

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

参考资料：https://docs.oracle.com/javase/9/docs/api/ Java/util/Properties.html#get-java.lang.Object-