zkoss/zk

/* BigDecimals.java

    Purpose:
        
    Description:
        
    History:
        Thu Apr 17 10:25:07     2003, Created by tomyeh

Copyright (C) 2002 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
    This program is distributed under LGPL Version 2.1 in the hope that
    it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.math;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.DecimalFormatSymbols;
import java.util.Locale;

import org.zkoss.lang.Objects;
import org.zkoss.util.Locales;

/**
 * Utilities and constants of big decimals.
 *
 * @author tomyeh
 */
public class BigDecimals {
    /** Represents 0 in big decimal.
     * @see #ONE
     * @see #MINUS_ONE
     */
    public static final BigDecimal ZERO = Objects.ZERO_BIG_DECIMAL;
    /** Represents 1 in big decimal.
     * @see #ZERO
     * @see #MINUS_ONE
     */
    public static final BigDecimal ONE = new BigDecimal(BigInteger.ONE);
    /** Represents -1 in big decimal.
     * @see #ZERO
     * @see #ONE
     */
    public static final BigDecimal MINUS_ONE = new BigDecimal(BigInteger.ONE.negate());
    
    /** Represents our number precision.
     */
    public static final int NUMBER_PRECISION = 38;
    
    /** Represents our number scale.
     */
    public static final int NUMBER_SCALE = 6;
    
    /** Represents our fine number precision.
     */
    public static final int FINE_NUMBER_PRECISION = 20;
    /** Represents our fine number scale.
     */
    public static final int FINE_NUMBER_SCALE = 8;

    /** Converts a double to a big decimal with a scale.
     *
     * <p>It is strongly deprecated to use new Decimal(double) since
     * the scale is unpredictable and usually surprising.
     * For example, BigDecimal(.1) will becomes
     * .1000000000000000055511151231257827021181583404541015625.
     * On the other hand, BigDecimal("0.1") will be 0.1 correctly.
     *
     * @param scale the BigDecimal's scale
     * @param roundingMode the rounding mode
     */
    public static final BigDecimal
    toBigDecimal(double v, int scale, int roundingMode) {
        return BigDecimal.valueOf(v).setScale(scale, roundingMode);
    }
    /** Converts a double to a big decimal with a scale.
     * It uses {@link BigDecimal#ROUND_HALF_UP}.
     */
    public static final BigDecimal toBigDecimal(double v, int scale) {
        return toBigDecimal(v, scale, BigDecimal.ROUND_HALF_UP);
    }
    /** Converts an integer to a big decimal with a scale.
     */
    public static final BigDecimal toBigDecimal(int v, int scale) {
        return new BigDecimal(BigIntegers.toBigInteger(v), scale);
    }
    /** Converts an integer to a big decimal with a scale.
     */
    public static final BigDecimal toBigDecimal(long v, int scale) {
        return new BigDecimal(BigIntegers.toBigInteger(v), scale);
    }
    /** Converts an integer to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(int v) {
        return v == 0 ? ZERO: new BigDecimal(BigIntegers.toBigInteger(v));
    }
    /** Converts a long to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(long v) {
        return v == 0 ? ZERO: new BigDecimal(BigIntegers.toBigInteger(v));
    }
    /** Converts a short to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(short v) {
        return v == 0 ? ZERO: new BigDecimal(BigIntegers.toBigInteger(v));
    }
    /** Converts a byte to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(byte v) {
        return v == 0 ? ZERO: new BigDecimal(BigIntegers.toBigInteger(v));
    }

    /** Converts an integer to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(Integer v) {
        return toBigDecimal(v.intValue());
    }
    /** Converts a long to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(Long v) {
        return toBigDecimal(v.longValue());
    }
    /** Converts a short to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(Short v) {
        return toBigDecimal(v.shortValue());
    }
    /** Converts a byte to a big decimal with a scale without.
     * losing precision -- zero scale in this case.
     */
    public static final BigDecimal toBigDecimal(Byte v) {
        return toBigDecimal(v.byteValue());
    }
    
    /**
     * Return a string representation of this BigDecimal without an exponent 
     * field, which respects the given locale.
     * @param locale if null, the current user locale is used.
     * @since 5.0.10
     */
    public static final String toLocaleString(BigDecimal bd, Locale locale) {
        if (locale == null)
            locale = Locales.getCurrent();
        final DecimalFormatSymbols symbols = new DecimalFormatSymbols(locale);
        final char DECIMAL = symbols.getDecimalSeparator();
        final char MINUS = symbols.getMinusSign();
        // only replace MINUS and DECIMAL as toPlainString() implementation
        // only involves these two chars. 
        return bd.toPlainString().replace('.', DECIMAL).replace('-', MINUS);
    }
    
}