/* java.lang.reflect.Field - reflection of Java fields   Copyright (C) 1998, 2001 Free Software Foundation, Inc.This file is part of GNU Classpath.GNU Classpath is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation; either version 2, or (at your option)any later version. GNU Classpath is distributed in the hope that it will be useful, butWITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNUGeneral Public License for more details.You should have received a copy of the GNU General Public Licensealong with GNU Classpath; see the file COPYING.  If not, write to theFree Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA02110-1301 USA.Linking this library statically or dynamically with other modules ismaking a combined work based on this library.  Thus, the terms andconditions of the GNU General Public License cover the wholecombination.As a special exception, the copyright holders of this library give youpermission to link this library with independent modules to produce anexecutable, regardless of the license terms of these independentmodules, and to copy and distribute the resulting executable underterms of your choice, provided that you also meet, for each linkedindependent module, the terms and conditions of the license of thatmodule.  An independent module is a module which is not derived fromor based on this library.  If you modify this library, you may extendthis exception to your version of the library, but you are notobligated to do so.  If you do not wish to do so, delete thisexception statement from your version. */package java.lang.reflect;/** * The Field class represents a member variable of a class. It also allows * dynamic access to a member, via reflection. This works for both * static and instance fields. Operations on Field objects know how to * do widening conversions, but throw {@link IllegalArgumentException} if * a narrowing conversion would be necessary. You can query for information * on this Field regardless of location, but get and set access may be limited * by Java language access controls. If you can't do it in the compiler, you * can't normally do it here either.<p> * * <B>Note:</B> This class returns and accepts types as Classes, even * primitive types; there are Class types defined that represent each * different primitive type.  They are <code>java.lang.Boolean.TYPE, * java.lang.Byte.TYPE,</code>, also available as <code>boolean.class, * byte.class</code>, etc.  These are not to be confused with the * classes <code>java.lang.Boolean, java.lang.Byte</code>, etc., which are * real classes.<p> * * Also note that this is not a serializable class.  It is entirely feasible * to make it serializable using the Externalizable interface, but this is * on Sun, not me. * * @author John Keiser * @author Eric Blake <ebb9@email.byu.edu> * @see Member * @see Class * @see Class#getField(String) * @see Class#getDeclaredField(String) * @see Class#getFields() * @see Class#getDeclaredFields() * @since 1.1 * @status updated to 1.4 */public final class Fieldextends AccessibleObject implements Member{  private Class declaringClass;  private String name;  private int slot;  /**   * This class is uninstantiable except natively.   */  private Field(Class declaringClass, String name, int slot)  {    this.declaringClass = declaringClass;    this.name = name;    this.slot = slot;  }  /**   * Gets the class that declared this field, or the class where this field   * is a non-inherited member.   * @return the class that declared this member   */  public Class getDeclaringClass()  {    return declaringClass;  }  /**   * Gets the name of this field.   * @return the name of this field   */  public String getName()  {    return name;  }  /**   * Gets the modifiers this field uses.  Use the <code>Modifier</code>   * class to interpret the values.  A field can only have a subset of the   * following modifiers: public, private, protected, static, final,   * transient, and volatile.   *   * @return an integer representing the modifiers to this Member   * @see Modifier   */  public native int getModifiers();  /**   * Gets the type of this field.   * @return the type of this field   */  public native Class getType();  /**   * Compare two objects to see if they are semantically equivalent.   * Two Fields are semantically equivalent if they have the same declaring   * class, name, and type. Since you can't creat a Field except through   * the VM, this is just the == relation.   *   * @param o the object to compare to   * @return <code>true</code> if they are equal; <code>false</code> if not   */  public boolean equals(Object o)  {    if (!(o instanceof Field))      return false;    Field that = (Field)o;     if (this.getDeclaringClass() != that.getDeclaringClass())      return false;    if (!this.getName().equals(that.getName()))      return false;    if (this.getType() != that.getType())      return false;    return true;  }  /**   * Get the hash code for the Field. The Field hash code is the hash code   * of its name XOR'd with the hash code of its class name.   *   * @return the hash code for the object.   */  public int hashCode()  {    return getDeclaringClass().getName().hashCode() ^ getName().hashCode();  }  /**   * Get a String representation of the Field. A Field's String   * representation is "&lt;modifiers&gt; &lt;type&gt;   * &lt;class&gt;.&lt;fieldname&gt;".<br> Example:   * <code>public transient boolean gnu.parse.Parser.parseComplete</code>   *   * @return the String representation of the Field   */  public String toString()  {    // 64 is a reasonable buffer initial size for field    StringBuffer sb = new StringBuffer(64);    Modifier.toString(getModifiers(), sb).append(' ');    sb.append(getType().getName()).append(' ');    sb.append(getDeclaringClass().getName()).append('.');    sb.append(getName());    return sb.toString();  }   /**   * Get the value of this Field.  If it is primitive, it will be wrapped   * in the appropriate wrapper type (boolean = java.lang.Boolean).<p>   *   * If the field is static, <code>o</code> will be ignored. Otherwise, if   * <code>o</code> is null, you get a <code>NullPointerException</code>,   * and if it is incompatible with the declaring class of the field, you   * get an <code>IllegalArgumentException</code>.<p>   *   * Next, if this Field enforces access control, your runtime context is   * evaluated, and you may have an <code>IllegalAccessException</code> if   * you could not access this field in similar compiled code. If the field   * is static, and its class is uninitialized, you trigger class   * initialization, which may end in a   * <code>ExceptionInInitializerError</code>.<p>   *   * Finally, the field is accessed, and primitives are wrapped (but not   * necessarily in new objects). This method accesses the field of the   * declaring class, even if the instance passed in belongs to a subclass   * which declares another field to hide this one.   *   * @param o the object to get the value of this Field from   * @return the value of the Field   * @throws IllegalAccessException if you could not normally access this field   *         (i.e. it is not public)   * @throws IllegalArgumentException if <code>o</code> is not an instance of   *         the class or interface declaring this field   * @throws NullPointerException if <code>o</code> is null and this field   *         requires an instance   * @throws ExceptionInInitializerError if accessing a static field triggered   *         class initialization, which then failed   * @see #getBoolean(Object)   * @see #getByte(Object)   * @see #getChar(Object)   * @see #getShort(Object)   * @see #getInt(Object)   * @see #getLong(Object)   * @see #getFloat(Object)   * @see #getDouble(Object)   */  public native Object get(Object o)    throws IllegalAccessException;  /**   * Get the value of this boolean Field. If the field is static,   * <code>o</code> will be ignored.   *   * @param o the object to get the value of this Field from   * @return the value of the Field   * @throws IllegalAccessException if you could not normally access this field   *         (i.e. it is not public)   * @throws IllegalArgumentException if this is not a boolean field of   *         <code>o</code>, or if <code>o</code> is not an instance of the   *         declaring class of this field   * @throws NullPointerException if <code>o</code> is null and this field   *         requires an instance   * @throws ExceptionInInitializerError if accessing a static field triggered   *         class initialization, which then failed   * @see #get(Object)   */  public native boolean getBoolean(Object o)    throws IllegalAccessException;  /**   * Get the value of this byte Field. If the field is static,   * <code>o</code> will be ignored.   *   * @param o the object to get the value of this Field from   * @return the value of the Field   * @throws IllegalAccessException if you could not normally access this field   *         (i.e. it is not public)   * @throws IllegalArgumentException if this is not a byte field of   *         <code>o</code>, or if <code>o</code> is not an instance of the   *         declaring class of this field   * @throws NullPointerException if <code>o</code> is null and this field   *         requires an instance   * @throws ExceptionInInitializerError if accessing a static field triggered   *         class initialization, which then failed   * @see #get(Object)   */  public native byte getByte(Object o)    throws IllegalAccessException;  /**   * Get the value of this Field as a char. If the field is static,   * <code>o</code> will be ignored.   *   * @throws IllegalAccessException if you could not normally access this field   *         (i.e. it is not public)   * @throws IllegalArgumentException if this is not a char field of   *         <code>o</code>, or if <code>o</code> is not an instance   *         of the declaring class of this field   * @throws NullPointerException if <code>o</code> is null and this field   *         requires an instance   * @throws ExceptionInInitializerError if accessing a static field triggered   *         class initialization, which then failed   * @see #get(Object)   */  public native char getChar(Object o)    throws IllegalAccessException;  /**   * Get the value of this Field as a short. If the field is static,   * <code>o</code> will be ignored.   *   * @param o the object to get the value of this Field from   * @return the value of the Field   * @throws IllegalAccessException if you could not normally access this field   *         (i.e. it is not public)   * @throws IllegalArgumentException if this is not a byte or short   *         field of <code>o</code>, or if <code>o</code> is not an instance   *         of the declaring class of this field   * @throws NullPointerException if <code>o</code> is null and this field   *         requires an instance   * @throws ExceptionInInitializerError if accessing a static field triggered   *         class initialization, which then failed