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Java Tutorial » Reflection » Class  
7.1.6.Demonstrates usage of various class information methodsPrevious/Next
/*
 *     file: ClassInfoDemo.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 ########## */


import java.io.Serializable;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

/**  
 * Demonstrates usage of various class information methods.
 *
 @author <a href=mailto:kraythe@arcor.de>Robert Simmons jr. (kraythe)</a>
 @version $Revision: 1.3 $
 */
public class ClassInfoDemo {
  /** 
   * Demonstration Method
   *
   @param args Demonstration Method.
   */
  public static void main(final String[] args) {
    final Set classes = new HashSet();
    classes.add(Class.class);
    classes.add(Comparable.class);
    classes.add(Serializable.class);
    classes.add(Integer.class);
    classes.add(int.class);
    classes.add(Float[].class);
    classes.add(String.class);
    classes.add(double[].class);
    classes.add(boolean.class);

    // --
    System.out.println("Finding interface Class objects in the set.");
    Iterator iter = classes.iterator();
    while (iter.hasNext()) {
      useIsInterface((Class)iter.next());
    }

    System.out.println("\nFinding primitive Class objects in the set.");
    iter = classes.iterator();
    while (iter.hasNext()) {
      useIsPrimitive((Class)iter.next());
    }

    System.out.println("\nFinding array Class objects in the set.");
    iter = classes.iterator();
    while (iter.hasNext()) {
      useIsArray((Class)iter.next());
    }
  }

  /** 
   * Demonstrates usage of <tt>isArray</tt> from Class.
   *
   @param dataType The data type to check.
   *
   @throws NullPointerException If the user passes null for dataType.
   */
  public static void useIsArray(final Class dataType) {
    if (dataType == null) {
      throw new NullPointerException();
    }
    if (dataType.isArray()) {
      System.out.print(dataType.getName());
      System.out.println("\t ==> " + dataType.getComponentType());
    }
  }

  /** 
   * Demonstrates usage of <tt>isInterface</tt> from Class.
   *
   @param dataType The data type to check.
   *
   @throws NullPointerException If the user passes null for dataType.
   */
  public static void useIsInterface(final Class dataType) {
    if (dataType == null) {
      throw new NullPointerException();
    }
    if (dataType.isInterface()) {
      System.out.println(dataType.getName());
    }
  }

  /** 
   * Demonstrates usage of <tt>isPrimitive</tt> from Class.
   *
   @param dataType The data type to check.
   *
   @throws NullPointerException If the user passes null for dataType.
   */
  public static void useIsPrimitive(final Class dataType) {
    if (dataType == null) {
      throw new NullPointerException();
    }
    if (dataType.isPrimitive()) {
      System.out.println(dataType.getName());
    }
  }
}

/* ########## End of File ########## */
7.1.Class
7.1.1. Get class name for various object
7.1.2. Create new instance
7.1.3. Get Canonical Name for a class
7.1.4. Demonstrates the use of getDeclaringClass()
7.1.5. Demonstrates the use of instance comparisons
7.1.6. Demonstrates usage of various class information methods
7.1.7. Demonstrates how to get declaration information on a Class
7.1.8. Demonstrates Dynamic class type checking
7.1.9. Demonstrates how to set public field objects
7.1.10. Demonstrates fetching nested class info from a Class object
7.1.11. Demonstration of how to obtain instances of java.lang.Class
7.1.12. Demonstrates getting immediate superclass info
7.1.13. Get declared method by name and parameter type
7.1.14. get class from an object
7.1.15. Returns the name of a class without the package name
7.1.16. Class comparator: compare and sort classes and their superclasses.
7.1.17. Is Type Compatible
7.1.18. Is the Same Signature
7.1.19. Determine whether the supplied string represents a well-formed fully-qualified Java classname.