java - 反射类仅初始化一次

Question

我想用Reflection读取各个子类extends类Demo的显示函数。

class Demo{
    public abstract void display();
}    

我只想初始化一次 clazz，我不知道如何检查 clazz 是否存在，请帮助我:D

public static void getDisplay(Class<? extends Demo> clazz) throws 
                   InstantiationException, IllegalAccessException {
        return clazz.newInstance().display();
}

Answer 1

根据您的逻辑尝试以下代码。

Class 对象上的

getSuperclass() 方法返回该类的父类(super class)。如果此类表示 Object 类、接口(interface)、基本类型或 void，则返回 null。

    // First took class name by using Class.forName(String fullyClassifiedClassName).   
    Class<?> superClass = Class.forName("childclass").getSuperclass();
    System.out.println(superClass); // prints "childclass"
    System.out.println(Object.class.getSuperclass()); // prints "null"

或者尝试这个代码，它在我的系统上运行良好。我希望这会有所帮助。

public class Main {
    public static void main(String[] args) {
      clazz c = new clazz();
        c.display();
    }
}
   class Demo
   {
      // Apply superclass's logic here
   }

    // sub class
class clazz extends Demo {
   public void display()
   {
       Demo val1 = new Demo();
      clazz val2 = new clazz();
      Class cls;
      cls = val1.getClass();
      System.out.println("Super class name = " + cls.getName());
      /* returns the superclass of the class(superClass) represented
         by this object */
      cls = cls.getSuperclass();
      System.out.println("Super is inherited by another class " + cls.getName());
      cls = val2.getClass();
      System.out.println("child Class Name " + cls.getName());
      /* returns the superclass of the class(subClass) represented
         by this object */
      cls = cls.getSuperclass();
      System.out.println("Child class extended by " + cls.getName());
   }
}