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Reflection in Java Made Easy

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Reflection in Java Made Easy

· Java Zone ·
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Reflection is one of the most powerful APIs available to a Java developer. Out of the box, the standard Java api is quite labourious to use, especially to search and query for particular methods.

For example, on a project I was recently working, to retrieve all the public methods off a class that returned a string, taking in zero parameters, with a method naming starting with to, the code would have to look like this:

 ArrayList<Method> results = new ArrayList<Method>();     
 for (Method m : String.class.getDeclaredMethods()) {                
     if (Modifier.isPublic(m.getModifiers()) &&           
             m.getReturnType().equals(String.class) &&    
             m.getParameterCount() == 0 &&                
             m.getName().startsWith("to")) {              
         results.add(m);                                  
     }                                                    
 }                                                                                                                  

So you could imagine, if you had anything more complicated, how this would end up looking. I looked around and found the Reflections library which makes this kind of work extremely easy. Converting the same query as above would look like this:

  Set<Method> results = getMethods(String.class,
          withModifier(Modifier.PUBLIC),
          withReturnType(String.class),     
          withParametersCount(0),
          withPrefix("to"));                                              

There's a lot more complicated queries that could be achieved with the library. The javadoc is a good place to look for more information. So in future, hopefully you consider using the library if you need to perform any reflections related operations in Java.

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