gcc/libjava/classpath/vm/reference/java/lang/reflect/Constructor.java

/* java.lang.reflect.Constructor - reflection of Java constructors
   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 modify
it under the terms of the GNU General Public License as published by
the 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, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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this exception to your version of the library, but you are not
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exception statement from your version. */


package java.lang.reflect;

import java.util.Arrays;

/**
 * The Constructor class represents a constructor of a class. It also allows
 * dynamic creation of an object, via reflection. Invocation on Constructor
 * objects knows how to do widening conversions, but throws
 * {@link IllegalArgumentException} if a narrowing conversion would be
 * necessary. You can query for information on this Constructor regardless
 * of location, but construction 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 java.lang.Class#getConstructor(Object[])
 * @see java.lang.Class#getDeclaredConstructor(Object[])
 * @see java.lang.Class#getConstructors()
 * @see java.lang.Class#getDeclaredConstructors()
 * @since 1.1
 * @status updated to 1.4
 */
public final class Constructor
extends AccessibleObject implements Member
{
  private Class clazz;
  private int slot;
  
  /**
   * This class is uninstantiable except from native code.
   */
  private Constructor(Class declaringClass,int slot)
  {
    this.clazz = declaringClass;
    this.slot = slot;
  }

  private Constructor()
  {
  }

  /**
   * Gets the class that declared this constructor.
   * @return the class that declared this member
   */
  public Class getDeclaringClass()
  {
    return clazz;
  }

  /**
   * Gets the name of this constructor (the non-qualified name of the class
   * it was declared in).
   * @return the name of this constructor
   */
  public String getName()
  {
    return getDeclaringClass().getName();
  }

  /**
   * Gets the modifiers this constructor uses.  Use the <code>Modifier</code>
   * class to interpret the values. A constructor can only have a subset of the
   * following modifiers: public, private, protected.
   *
   * @return an integer representing the modifiers to this Member
   * @see Modifier
   */
  public native int getModifiers();

  /**
   * Get the parameter list for this constructor, in declaration order. If the
   * constructor takes no parameters, returns a 0-length array (not null).
   *
   * @return a list of the types of the constructor's parameters
   */
  public native Class[] getParameterTypes();

  /**
   * Get the exception types this constructor says it throws, in no particular
   * order. If the constructor has no throws clause, returns a 0-length array
   * (not null).
   *
   * @return a list of the types in the constructor's throws clause
   */
  public native Class[] getExceptionTypes();

  /**
   * Compare two objects to see if they are semantically equivalent.
   * Two Constructors are semantically equivalent if they have the same
   * declaring class and the same parameter list.  This ignores different
   * exception clauses, but since you can't create a Method 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 Constructor))
      return false;
    Constructor that = (Constructor)o; 
    if (this.getDeclaringClass() != that.getDeclaringClass())
      return false;
    if (!Arrays.equals(this.getParameterTypes(), that.getParameterTypes()))
      return false;
    return true;
  }

  /**
   * Get the hash code for the Constructor. The Constructor hash code is the
   * hash code of the declaring class's name.
   *
   * @return the hash code for the object
   */
  public int hashCode()
  {
    return getDeclaringClass().getName().hashCode();
  }

  /**
   * Get a String representation of the Constructor. A Constructor's String
   * representation is "&lt;modifier&gt; &lt;classname&gt;(&lt;paramtypes&gt;)
   * throws &lt;exceptions&gt;", where everything after ')' is omitted if
   * there are no exceptions.<br> Example:
   * <code>public java.io.FileInputStream(java.lang.Runnable)
   * throws java.io.FileNotFoundException</code>
   *
   * @return the String representation of the Constructor
   */
  public String toString()
  {
    // 128 is a reasonable buffer initial size for constructor
    StringBuffer sb = new StringBuffer(128);
    Modifier.toString(getModifiers(), sb).append(' ');
    sb.append(getDeclaringClass().getName()).append('(');
    Class[] c = getParameterTypes();
    if (c.length > 0)
      {
        sb.append(c[0].getName());
        for (int i = 1; i < c.length; i++)
          sb.append(',').append(c[i].getName());
      }
    sb.append(')');
    c = getExceptionTypes();
    if (c.length > 0)
      {
        sb.append(" throws ").append(c[0].getName());
        for (int i = 1; i < c.length; i++)
          sb.append(',').append(c[i].getName());
      }
    return sb.toString();
  }
 
  /**
   * Create a new instance by invoking the constructor. Arguments are
   * automatically unwrapped and widened, if needed.<p>
   *
   * If this class is abstract, you will get an
   * <code>InstantiationException</code>. If the constructor takes 0
   * arguments, you may use null or a 0-length array for <code>args</code>.<p>
   *
   * If this Constructor enforces access control, your runtime context is
   * evaluated, and you may have an <code>IllegalAccessException</code> if
   * you could not create this object in similar compiled code. If the class
   * is uninitialized, you trigger class initialization, which may end in a
   * <code>ExceptionInInitializerError</code>.<p>
   *
   * Then, the constructor is invoked. If it completes normally, the return
   * value will be the new object. If it completes abruptly, the exception is
   * wrapped in an <code>InvocationTargetException</code>.
   *
   * @param args the arguments to the constructor
   * @return the newly created object
   * @throws IllegalAccessException if the constructor could not normally be
   *         called by the Java code (i.e. it is not public)
   * @throws IllegalArgumentException if the number of arguments is incorrect;
   *         or if the arguments types are wrong even with a widening
   *         conversion
   * @throws InstantiationException if the class is abstract
   * @throws InvocationTargetException if the constructor throws an exception
   * @throws ExceptionInInitializerError if construction triggered class
   *         initialization, which then failed
   */
  public Object newInstance(Object args[])
    throws InstantiationException, IllegalAccessException,
           InvocationTargetException
  {
    return constructNative(args, clazz, slot);
  }

  private native Object constructNative(Object[] args, Class declaringClass,
                                        int slot)
    throws InstantiationException, IllegalAccessException,
           InvocationTargetException;
}