Accessing protected method in test case using Java Reflection

Question

Am trying to obtain and invoke a protected method residing in a different class and also different package using Java Reflection.

Class containing protected method:

package com.myapp;  public class MyServiceImpl {     protected List<String> retrieveItems(String status) {          // Implementation    } } 

Calling class:

package xxx.myapp.tests;  import com.myapp.MyServiceImpl;  public class MyTestCase {      List<String> items;      public void setUp() throws Exception {           MyServiceImpl service = new MyServiceImpl();          Class clazz = service.getClass();           // Fails at the next line:          Method retrieveItems = clazz.getDeclaredMethod("retrieveItems");           // How to invoke the method and return List<String> items?          // tried this but it fails?          retrieveItems.invoke(clazz, "S");     } } 

The compiler throws this Exception:

java.lang.NoSuchMethodException: com.myapp.MyServiceImpl.retrieveItems() 

Answer 1

The problem with your code is that the getDeclaredMethod function looks up a function both by name and by argument types. With the call

Method retrieveItems = clazz.getDeclaredMethod("retrieveItems"); 

The code will look for a method retrieveItems() with no arguments. The method you're looking for does take an argument, a string, so you should call

Method retrieveItems = clazz.getDeclaredMethod("retrieveItems", String.class); 

This will tell Java to search for retrieveItems(String), which is what you're looking for.