Demonstration of how to obtain instances of java.lang.Class : Class « Reflection « Java Tutorial

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/*
 *     file: ObtainingClassInstances.java
 *  package: oreilly.hcj.reflection
 *
 * This software is granted under the terms of the Common Public License,
 * CPL, which may be found at the following URL:
 * http://www-124.ibm.com/developerworks/oss/CPLv1.0.htm
 *
 * Copyright(c) 2003-2005 by the authors indicated in the @author tags.
 * All Rights are Reserved by the various authors.
 *
########## DO NOT EDIT ABOVE THIS LINE ########## */


/**  
 * Demonstration of how to obtain instances of <tt>java.lang.Class</tt>.
 *
 * @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
 * @version $Revision: 1.3 $
 */
public class ObtainingClassInstances {
  /** An Integer object */
  protected static Integer someInteger = new Integer(10);

  /** A generic object. */
  protected static Object someObject = null;

  /** A String. */
  protected static String someString = new String("Hardcore Java");

  /** An int. */
  protected static int someInt = 15;

  /** An array of ints. */
  protected static int[] intArray = new int[] { 4, 5, 7, 9 };

  /** 
   * Main method.
   *
   * @param args Command line arguments.
   */
  public static void main(final String[] args) {
    // -- Print out the Class instances. 
    System.out.println(someInteger.getClass());
    System.out.println(someString.getClass());
    System.out.println(intArray.getClass());
    System.out.println(Object.class);
    System.out.println(Integer.class);
    System.out.println(int.class);
    System.out.println(String.class);
    System.out.println(Comparable.class);
    System.out.println(Object[].class);

    // -- Things that WON'T work
    // System.out.println(someObject.getClass());  // <= Exception 
    // System.out.println(someInt.getClass()); // <= Compiler errror
  }

  /** 
   * Demonstration of a method that doesnt check for null.
   *
   * @param obj The object passed.
   */
  public void writeClass(final Object obj) {
    System.out.println(obj.getClass());
  }
}

/* ########## End of File ########## */