Java Class getDeclaredConstructors()用法及代码示例

java.lang.Class类的getDeclaredConstructors()方法用于获取此类的构造函数，这些构造函数是私有，公共，受保护或默认的构造函数。该方法以构造函数对象数组的形式返回此类的构造函数。

用法:

public Constructor[] getDeclaredConstructors()
                      throws SecurityException

参数：此方法不接受任何参数。

返回值：此方法以构造函数对象数组的形式返回此类的构造函数。

异常如果存在安全管理器且不满足安全条件，则此方法将引发SecurityException。

下面的程序演示了getDeclaredConstructors()方法。

示例1:

// Java program to demonstrate 
// getDeclaredConstructors() method 
  
import java.util.*; 
  
public class Test { 
    public static void main(String[] args) 
        throws ClassNotFoundException 
    { 
  
        // returns the Class object for this class 
        Class myClass = Class.forName("Test"); 
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString()); 
  
        // Get the constructors of myClass 
        // using getDeclaredConstructors() method 
        System.out.println( 
            "DeclaredConstructors of myClass: "
            + Arrays.toString( 
                  myClass.getDeclaredConstructors())); 
    } 
}

输出：

Class represented by myClass: class Test
DeclaredConstructors of myClass: [public Test()]

示例2:

// Java program to demonstrate  
//getDeclaredConstructors() method 
  
import java.util.*; 
  
class Main { 
  
    public Object obj; 
  
    private Main() 
    { 
  
        class Arr { 
        }; 
  
        obj = new Arr(); 
    } 
  
    public static void main(String[] args) 
        throws ClassNotFoundException 
    { 
        // returns the Class object for this class 
        Class myClass = Class.forName("Main"); 
  
        System.out.println("Class represented by myClass: "
                           + myClass.toString()); 
  
        // Get the constructors of myClass 
        // using getDeclaredConstructors() method 
        System.out.println( 
            "DeclaredConstructors of myClass: "
            + Arrays.toString( 
                  myClass.getDeclaredConstructors())); 
    } 
}

输出：

Class represented by myClass: class Main
DeclaredConstructors of myClass: [private Main()]

参考： https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#getDeclaredConstructors–

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注：本文由纯净天空筛选整理自srinam大神的英文原创作品 Class getDeclaredConstructors() 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。