在Java中从String创建实例

Question

如果我有2个类,"A"和"B",我怎么能创建一个通用工厂,所以我只需要将类名作为字符串传递给接收实例？

例:

public static void factory(String name) {
     // An example of an implmentation I would need, this obviously doesn't work
      return new name.CreateClass();
}

谢谢!

乔尔

Answer 1

Class c= Class.forName(className);
return c.newInstance();//assuming you aren't worried about constructor .

• 的javadoc

用于调用带参数的构造函数

 public static Object createObject(Constructor constructor,
      Object[] arguments) {

    System.out.println("Constructor: " + constructor.toString());
    Object object = null;

    try {
      object = constructor.newInstance(arguments);
      System.out.println("Object: " + object.toString());
      return object;
    } catch (InstantiationException e) {
      //handle it
    } catch (IllegalAccessException e) {
      //handle it
    } catch (IllegalArgumentException e) {
      //handle it
    } catch (InvocationTargetException e) {
      //handle it
    }
    return object;
  }
}

有一个看看

Answer 2

您可以看一看Reflection：

import java.awt.Rectangle;

public class SampleNoArg {

   public static void main(String[] args) {
      Rectangle r = (Rectangle) createObject("java.awt.Rectangle");
      System.out.println(r.toString());
   }

   static Object createObject(String className) {
      Object object = null;
      try {
          Class classDefinition = Class.forName(className);
          object = classDefinition.newInstance();
      } catch (InstantiationException e) {
          System.out.println(e);
      } catch (IllegalAccessException e) {
          System.out.println(e);
      } catch (ClassNotFoundException e) {
          System.out.println(e);
      }
      return object;
   }
}