All information about a class : Generic « Reflection « Java

1. Java
2. Reflection
3. Generic

All information about a class

     

/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import static java.lang.System.out;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;

enum ClassMember {
  CONSTRUCTOR, FIELD, METHOD, CLASS, ALL
}

public class ClassSpy {
  public static void main(String... args) {
    try {
      Class<?> c = Class.forName(args[0]);
      out.format("Class:%n  %s%n%n", c.getCanonicalName());

      Package p = c.getPackage();
      out.format("Package:%n  %s%n%n", (p != null ? p.getName()
          : "-- No Package --"));

      for (int i = 1; i < args.length; i++) {
        switch (ClassMember.valueOf(args[i])) {
        case CONSTRUCTOR:
          printMembers(c.getConstructors(), "Constructor");
          break;
        case FIELD:
          printMembers(c.getFields(), "Fields");
          break;
        case METHOD:
          printMembers(c.getMethods(), "Methods");
          break;
        case CLASS:
          printClasses(c);
          break;
        case ALL:
          printMembers(c.getConstructors(), "Constuctors");
          printMembers(c.getFields(), "Fields");
          printMembers(c.getMethods(), "Methods");
          printClasses(c);
          break;
        default:
          assert false;
        }
      }

      // production code should handle these exceptions more gracefully
    } catch (ClassNotFoundException x) {
      x.printStackTrace();
    }
  }

  private static void printMembers(Member[] mbrs, String s) {
    out.format("%s:%n", s);
    for (Member mbr : mbrs) {
      if (mbr instanceof Field)
        out.format("  %s%n", ((Field) mbr).toGenericString());
      else if (mbr instanceof Constructor)
        out.format("  %s%n", ((Constructor) mbr).toGenericString());
      else if (mbr instanceof Method)
        out.format("  %s%n", ((Method) mbr).toGenericString());
    }
    if (mbrs.length == 0)
      out.format("  -- No %s --%n", s);
    out.format("%n");
  }

  private static void printClasses(Class<?> c) {
    out.format("Classes:%n");
    Class<?>[] clss = c.getClasses();
    for (Class<?> cls : clss)
      out.format("  %s%n", cls.getCanonicalName());
    if (clss.length == 0)
      out.format("  -- No member interfaces, classes, or enums --%n");
    out.format("%n");
  }
}

   
    
    
    
    
  

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