Java Fundamentals - Reflection

Runtime information

• getClass method;  get the class description

Class<?> c = obj.getClass();

• c.getSimpleName();

Class.forName passing fully qualified type name

• c.forName("quelified_full_name")

Class<?> c =  Class.forName("com.company.Bank")

• typeName.class

• getModifiers

Return the class modifiers: public, private, protected, final

int modifiers = c.getModifiers();

if( Modifier.isPublic(modifiers) )

  System.out.println("Is a public method")

Type Members

• Types declared & members only (Public, protected, private)

getDeclaredFields

getDeclaredMethods

getDeclaredConstructors

• Type's declared & inherited members (Public only)

• getFields -  Return Field[]

for(Field f: arr)

    System.out.println(f.getName() +" " + f.getType() );

• getMethods - Return Methods[]

To avoid methods from the Object class

  Methods[] me = c.getMethods();
  for(Method m: methods){
         if(m.getDeclaringClass() !=  Object.class  )
  }

• getConstructors
• getField( ... )
• getMethod(...)
• getConstructor( ...)

Real Example

void startWork( String className, Object  classTarget){

try{

   Class<?> classTarget = Class.forName(classTarget);

   ClassToWork worker = (ClassToWork) classTarget.newInstance();

  worker.executeMethod( classTarget  );

  worker.doWork();

}catch(Exception e){}

}