public class MethodAccessExampleWithArgs { private final int i;  public MethodAccessExampleWithArgs(int i_) {  i = i_; }  private void bar(int j, String msg) {  System.out.println("Private Method 'bar' successfully accessed : "    + i + ", " + j + " : " + msg + "!"); }  // Using Reflection public static Method makeMethod() {  Method meth = null;   try {   Class[] argTypes = new Class[] { int.class, String.class };    meth = MethodAccessExampleWithArgs.class.getDeclaredMethod("bar",     argTypes);    meth.setAccessible(true);  } catch (IllegalArgumentException e) {   e.printStackTrace();  } catch (NoSuchMethodException e) {   e.printStackTrace();  } catch (SecurityException e) {   e.printStackTrace();  }   return meth; }  // Using method handles public static MethodHandle makeMh() {  MethodHandle mh;   MethodType desc = MethodType.methodType(void.class, int.class,    String.class);   try {   mh = MethodHandles.lookup().findVirtual(     MethodAccessExampleWithArgs.class, "bar", desc);   System.out.println("mh=" + mh);  } catch (NoAccessException e) {   throw (AssertionError) new AssertionError().initCause(e);  }  return mh; }}

Following, is a class meant to test the two approaches of accessing the private method “bar” :

public class MethodAccessMain {  private static void withReflectionArgs() {  Method meth = MethodAccessExampleWithArgs.makeMethod();   MethodAccessExampleWithArgs mh0 = new MethodAccessExampleWithArgs(0);  MethodAccessExampleWithArgs mh1 = new MethodAccessExampleWithArgs(1);   try {   System.out.println("Invocation using Reflection");   meth.invoke(mh0, 5, "Jabba the Hutt");   meth.invoke(mh1, 7, "Boba Fett");  } catch (IllegalAccessException e) {   e.printStackTrace();  } catch (IllegalArgumentException e) {   e.printStackTrace();  } catch (InvocationTargetException e) {   e.printStackTrace();  } }  private static void withMhArgs() {  MethodHandle mh = MethodAccessExampleWithArgs.makeMh();   MethodAccessExampleWithArgs mh0 = new MethodAccessExampleWithArgs(0);  MethodAccessExampleWithArgs mh1 = new MethodAccessExampleWithArgs(1);   try {   System.out.println("Invocation using Method Handle");   mh.invokeExact(mh0, 42, "R2D2");   mh.invokeExact(mh1, 43, "C3PO");  } catch (Throwable e) {   e.printStackTrace();  } }  public static void main(String[] args) {  withReflectionArgs();  withMhArgs(); }}

Related Article:

• A glimpse at Java 7 MethodHandle and its usage

References :

• A glimpse at MethodHandle and its usage from our JCG partners atJava 7 Developer Blog
• The Well-Grounded Java Developer

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