www.pudn.com > j2me_cldc-1_1-fcs-src-winunix.rar > Character.java

/*
 * Copyright © 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 */

package java.lang;
import com.sun.cldc.i18n.uclc.*;

/**
 * The Character class wraps a value of the primitive type char
 * in an object. An object of type Character contains a
 * single field whose type is char.
 * 

 * In addition, this class provides several methods for determining
 * the type of a character and converting characters from uppercase
 * to lowercase and vice versa.
 * 

 * Character information is based on the Unicode Standard, version 3.0.
 * However, in order to reduce footprint, by default the character
 * property and case conversion operations in CLDC are available
 * only for the ISO Latin-1 range of characters.  Other Unicode
 * character blocks can be supported as necessary.
 * 

 *
 * @author  Lee Boynton
 * @author  Guy Steele
 * @author  Akira Tanaka
 * @version 12/17/01 (CLDC 1.1)
 * @since   JDK1.0, CLDC 1.0
 */

/*
 * Implementation note:
 * 
 * The character property and case conversion facilities 
 * provided by the CLDC reference implementation can be
 * extended by overriding an implementation class called 
 * DefaultCaseConverter.  Refer to the end of this file
 * for details.
 */

public final class Character extends Object {

    /**
     * The minimum radix available for conversion to and from Strings.
     *
     * @see     java.lang.Integer#toString(int, int)
     * @see     java.lang.Integer#valueOf(java.lang.String)
     */
    public static final int MIN_RADIX = 2;

    /**
     * The maximum radix available for conversion to and from Strings.
     *
     * @see     java.lang.Integer#toString(int, int)
     * @see     java.lang.Integer#valueOf(java.lang.String)
     */
    public static final int MAX_RADIX = 36;

    /**
     * The constant value of this field is the smallest value of type
     * char.
     *
     * @since   JDK1.0.2
     */
    public static final char   MIN_VALUE = '\u0000';

    /**
     * The constant value of this field is the largest value of type
     * char.
     *
     * @since   JDK1.0.2
     */
    public static final char   MAX_VALUE = '\uffff';

    /**
     * The value of the Character.
     */
    private char value;

    /**
     * Constructs a Character object and initializes it so
     * that it represents the primitive value argument.
     *
     * @param  value   value for the new Character object.
     */
    public Character(char value) {
        this.value = value;
    }

    /**
     * Returns the value of this Character object.
     * @return  the primitive char value represented by
     *          this object.
     */
    public char charValue() {
        return value;
    }

    /**
     * Returns a hash code for this Character.
     * @return  a hash code value for this object.
     */
    public int hashCode() {
        return (int)value;
    }

    /**
     * Compares this object against the specified object.
     * The result is true if and only if the argument is not
     * null and is a Character object that
     * represents the same char value as this object.
     *
     * @param   obj   the object to compare with.
     * @return  true if the objects are the same;
     *          false otherwise.
     */
    public boolean equals(Object obj) {
        if (obj instanceof Character) {
            return value == ((Character)obj).charValue();
        }
        return false;
    }

    /**
     * Returns a String object representing this character's value.
     * Converts this Character object to a string. The
     * result is a string whose length is 1. The string's
     * sole component is the primitive char value represented
     * by this object.
     *
     * @return  a string representation of this object.
     */
    public String toString() {
        char buf[] = {value};
        return String.valueOf(buf);
    }

   /**
     * Determines if the specified character is a lowercase character.
     * 

     * Note that by default CLDC only supports 
     * the ISO Latin-1 range of characters.
     * 

     * Of the ISO Latin-1 characters (character codes 0x0000 through 0x00FF),
     * the following are lowercase:
     * 

     * a b c d e f g h i j k l m n o p q r s t u v w x y z
     * \u00DF \u00E0 \u00E1 \u00E2 \u00E3 \u00E4 \u00E5 \u00E6 \u00E7
     * \u00E8 \u00E9 \u00EA \u00EB \u00EC \u00ED \u00EE \u00EF \u00F0
     * \u00F1 \u00F2 \u00F3 \u00F4 \u00F5 \u00F6 \u00F8 \u00F9 \u00FA
     * \u00FB \u00FC \u00FD \u00FE \u00FF
     *
     * @param   ch   the character to be tested.
     * @return  true if the character is lowercase;
     *          false otherwise.
     * @since   JDK1.0
     */
    public static boolean isLowerCase(char ch) {
        return caseConverter().isLowerCase(ch);
    }

   /**
     * Determines if the specified character is an uppercase character.
     * 

     * Note that by default CLDC only supports 
     * the ISO Latin-1 range of characters.
     * 

     * Of the ISO Latin-1 characters (character codes 0x0000 through 0x00FF),
     * the following are uppercase:
     * 

     * A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
     * \u00C0 \u00C1 \u00C2 \u00C3 \u00C4 \u00C5 \u00C6 \u00C7
     * \u00C8 \u00C9 \u00CA \u00CB \u00CC \u00CD \u00CE \u00CF \u00D0
     * \u00D1 \u00D2 \u00D3 \u00D4 \u00D5 \u00D6 \u00D8 \u00D9 \u00DA
     * \u00DB \u00DC \u00DD \u00DE
     *
     * @param   ch   the character to be tested.
     * @return  true if the character is uppercase;
     *          false otherwise.
     * @see     java.lang.Character#isLowerCase(char)
     * @see     java.lang.Character#toUpperCase(char)
     * @since   1.0
     */
    public static boolean isUpperCase(char ch) {
        return caseConverter().isUpperCase(ch);
    }

    /**
     * Determines if the specified character is a digit.
     *
     * @param   ch   the character to be tested.
     * @return  true if the character is a digit;
     *          false otherwise.
     * @since   JDK1.0
     */
    public static boolean isDigit(char ch) {
        return caseConverter().isDigit(ch);
    }

    /**
     * The given character is mapped to its lowercase equivalent; if the
     * character has no lowercase equivalent, the character itself is
     * returned.
     * 

     * Note that by default CLDC only supports 
     * the ISO Latin-1 range of characters.
     *
     * @param   ch   the character to be converted.
     * @return  the lowercase equivalent of the character, if any;
     *          otherwise the character itself.
     * @see     java.lang.Character#isLowerCase(char)
     * @see     java.lang.Character#isUpperCase(char)
     * @see     java.lang.Character#toUpperCase(char)
     * @since   JDK1.0
     */
    public static char toLowerCase(char ch) {
        return caseConverter().toLowerCase(ch);
    }

    /**
     * Converts the character argument to uppercase; if the
     * character has no uppercase equivalent, the character itself is
     * returned.
     * 

     * Note that by default CLDC only supports 
     * the ISO Latin-1 range of characters.
     *
     * @param   ch   the character to be converted.
     * @return  the uppercase equivalent of the character, if any;
     *          otherwise the character itself.
     * @see     java.lang.Character#isLowerCase(char)
     * @see     java.lang.Character#isUpperCase(char)
     * @see     java.lang.Character#toLowerCase(char)
     * @since   JDK1.0
     */
    public static char toUpperCase(char ch) {
        return caseConverter().toUpperCase(ch);
    }

    /**
     * Returns the numeric value of the character ch in the
     * specified radix.
     *
     * @param   ch      the character to be converted.
     * @param   radix   the radix.
     * @return  the numeric value represented by the character in the
     *          specified radix.
     * @see     java.lang.Character#isDigit(char)
     * @since   JDK1.0
     */
    public static int digit(char ch, int radix) {
        return caseConverter().digit(ch, radix);
    }

    /*
     * Implementation note:
     *
     * The code below allows the default case converter class
     * to be overridden by defining a system property called 
     * "java.lang.Character.caseConverter".
     *
     * By default, the system only supports the ISO Latin-1
     * range of characters for character properties and 
     * case conversion.
     */

static DefaultCaseConverter cc;

static DefaultCaseConverter caseConverter() {

        if (cc != null) {
           return cc;
        }

        String ccName = "?";

        try {
            /* Get the default encoding name */
            ccName = System.getProperty("java.lang.Character.caseConverter");
            if (ccName == null) {
                ccName = "com.sun.cldc.i18n.uclc.DefaultCaseConverter";
            }

            /* Using the decoder names lookup a class to implement the reader */
            Class clazz = Class.forName(ccName);

            /* Return a new instance */
            cc = (DefaultCaseConverter)clazz.newInstance();

        } catch (Exception x) {
            throw new RuntimeException("Cannot find case converter class "+ccName+" -> "+x.getMessage());
        }

        return cc;
    }

}