package java.lang;

/**
 * An immutable string of characters.
 */
public final class String
{
  // NOTE: The state of this class is mapped to
  // native code (see vmsrc/classes.h).

  char[] characters; // package protected, so StringUtils can access it

  /**
   * Create a String from a character array.
   * @param c the character array
   * @param off the offset - usually 0
   * @param len the length of the String - must not be greater than c.length
   **/
  public String (char[] c, int off, int len)
  {
    characters = new char[len];
    System.arraycopy (c, off, characters, 0, len);
  }

  /**
   * Return the length of the String in characters
   * @return the length of the String
   **/
  public int length()
  {
    return characters.length;
  }

  /**
   * Return the character at the given index
   * @return the characters at the given index
   **/
  public char charAt(int index) 
  {
    return characters[index];
  }

  /**
   * Converts the String into an array of characters
   * @return the character Array
   **/
  public char[] toCharArray()
  {
    int len = characters.length;
    char[] ca = new char[len];
    System.arraycopy (characters, 0, ca, 0, len);
    return ca;
  }

  /**
   * Converts an Object to a String
   * @return the String that represents the object
   **/
  public static String valueOf (Object aObj)
  {
    return aObj.toString();
  }

  /**
   * Returns itself.
   * @return the String itself
   */
  public String toString()
  {
    return this;
  }
  
  /**
   * Compares the String with an Object
   * @return true if the String is equal to the object, false otherwise
   **/
  public boolean equals(Object other)
  {
    if (other == null)
      return false;
      
    try {
      String os = (String)other;
      if (os.characters.length != characters.length)
         return false;
         
      for (int i=0; i<characters.length; i++)
      {
        if (characters[i] != os.characters[i])
          return false;
      }
      
      return true;
    } catch (ClassCastException e) {
    }    
    return false;
  }
}