Invoking Methods

We will use an example to better understand FEST-Reflect's fluent interface for method invocation.

Let's assume we have a simple class Names that defines the following methods: 

class Names {

  private final List<String> names = new ArrayList<String>();

  void clear() {
    names.clear();
  }

  int size() {
    return names.size();
  }

  void add(String name) {
    names.add(name);  
  }

  String get(int index) {
    return names.get(index);
  }  

}

The following sections compares method invocation using Java Reflection and FEST-Reflect. We will assume that we have the variable 'names' of type Names. We are also going to assume the following static import: 

import static org.fest.reflect.core.Reflection.method;

Invoking methods without parameters and return type 'void'

Java Reflection: 

Method method = Names.class.getMethod("clear");

AccessController.doPrivileged(new PrivilegedAction<Void>() {
  public Void run() {
    method.setAccessible(true);
    return null;
  }
});    

method.invoke(names);

FEST-Reflect: 

method("clear").in(names).invoke();

Invoking methods with parameters and return type 'void'

Java Reflection: 

Method method = Names.class.getMethod("add", String.class);

AccessController.doPrivileged(new PrivilegedAction<Void>() {
  public Void run() {
    method.setAccessible(true);
    return null;
  }
});    

method.invoke(names, "Yoda");

FEST-Reflect: 

method("add").withParameterTypes(String.class)
             .in(names)
             .invoke("Yoda");

Invoking methods without parameters and return type other than 'void'

Java Reflection: 

Method method = Names.class.getMethod("size");

AccessController.doPrivileged(new PrivilegedAction<Void>() {
  public Void run() {
    method.setAccessible(true);
    return null;
  }
});    

int size = (Integer) method.invoke(names);

FEST-Reflect: 

int size = method("size").withReturnType(int.class)
                         .in(names)
                         .invoke();

Invoking methods with parameters and return type other than 'void'

Java Reflection: 

Method method = Names.class.getMethod("get", int.class);

AccessController.doPrivileged(new PrivilegedAction<Void>() {
  public Void run() {
    method.setAccessible(true);
    return null;
  }
});    

String name = (String) method.invoke(names, 8);

FEST-Reflect: 

String name = method("get").withReturnType(String.class)
                           .withParameterTypes(int.class)
                           .in(names)
                           .invoke(8);