java.lang.Void类的解析与使用详解

package java.lang;
/**
 * The {@code Void} class is an uninstantiable placeholder class to hold a
 * reference to the {@code Class} object representing the Java keyword
 * void.
 *
 * @author unascribed
 * @since  JDK1.1
 */
public final
class Void {
  /**
   * The {@code Class} object representing the pseudo-type corresponding to
   * the keyword {@code void}.
   */
  @SuppressWarnings("unchecked")
  public static final Class<Void> TYPE = (Class<Void>) Class.getPrimitiveClass("void");

  /*
   * The Void class cannot be instantiated.
   */
  private Void() {}
}

public static final Class<Void> TYPE = (Class<Void>) Class.getPrimitiveClass("void");

public Void test() { 
  return null;
}

Future<Void> f = pool.submit(new Callable() {
  @Override
  public Void call() throws Exception {
    ......
    return null;
  }
    
});

public class Test {
  public void hello() { }
  public static void main(String args[]) {
    for (Method method : Test.class.getMethods()) {
      if (method.getReturnType().equals(Void.TYPE)) {
        System.out.println(method.getName());
      }
    }
  }
}

main
hello
wait
wait
wait
notify
notifyAll

Void nil = null;

public final
class Void {
  /**
   * The {@code Class} object representing the pseudo-type corresponding to
   * the keyword {@code void}.
   */
  @SuppressWarnings("unchecked")
  public static final Class<Void> TYPE = (Class<Void>) Class.getPrimitiveClass("void");

  /*
   * The Void class cannot be instantiated.
   */
  private Void() {}
}

 Void function(int a, int b) {
  //do something
  return null;
 }

public class Test {
  public void print(String v) {}
  public static void main(String args[]){
    for(Method method : Test.class.getMethods()) {
      if(method.getReturnType().equals(Void.TYPE)) {
        System.out.println(method.getName());
      }
    }
  }
}