Java Class getDeclaredMethod()用法及代码示例

java.lang.Class类的getDeclaredMethod()方法用于获取具有指定参数类型的此类的指定方法。该方法以Method对象的形式返回此类的指定方法。

用法:

public Method getDeclaredMethod(String methodName, 
                            Class[] parameterType)
       throws NoSuchMethodException, SecurityException

参数：此方法接受两个参数：

• methodName这是要获得的方法。
• parameterType这是指定方法的参数类型的数组。

返回值：此方法以Method对象的形式返回此类的指定方法。

异常该方法抛出：

• NoSuchMethodException如果找不到具有指定名称的方法。
• NullPointerException 如果名称为null
• SecurityException如果存在安全管理员并且不满足安全条件。

  下面的程序演示了getDeclaredMethod()方法。

  示例1:

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

  输出：

  Class represented by myClass: class Test
  func Method of myClass: public void Test.func()
  

  示例2:

  // Java program to demonstrate 
  // getDeclaredMethod() method 
    
  import java.util.*; 
    
  class Main { 
    
      private void func() {} 
    
      public static void main(String[] args) 
          throws ClassNotFoundException, NoSuchMethodException 
      { 
          // returns the Class object for this class 
          Class myClass = Class.forName("Main"); 
    
          System.out.println("Class represented by myClass: "
                             + myClass.toString()); 
    
          String methodName = "func"; 
          Class[] parameterType = null; 
    
          try { 
              // Get the method of myClass 
              // using getDeclaredMethod() method 
              System.out.println( 
                  methodName + " Method of myClass: "
                  + myClass.getDeclaredMethod( 
                        methodName, parameterType)); 
          } 
          catch (Exception e) { 
              System.out.println(e); 
          } 
      } 
  }

  输出：

  Class represented by myClass: class Main
  func Method of myClass: private void Main.func()
  

  参考： https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#getDeclaredMethod-java.lang.String-java.lang.Class…-