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An easy to use Application Programming Interface (API) for working with MARC and MARCXML in Java.

There is a newer version: 2.6.12

/** A formatter that is like a << new DecimalFormat("00000") with
 * setMaximumIntegerDigits(5), but if
 * the number to be formatted is greater than 99999, it will truncate
 * it to 99999 instead of just writing out 5 least significant digits.
 * If you'd like 00000 instead of 99999, you can set static variable
 * overflowRepresentation to 0.
 */

package org.marc4j.util;

import java.text.DecimalFormat;
import java.text.FieldPosition;

public class CustomDecimalFormat extends DecimalFormat {

    /**
     * The serialVersionUID for the class.
     */
    private static final long serialVersionUID = 2377613559633630577L;

    static String formatString = "00000000000000000000";

    static String maxString = "99999999999999999999";

    public final static int REP_ALL_ZEROS = 0;

    public final static int REP_ALL_NINES = 1;

    public final static int REP_TRUNCATE = 2;

    int overflowRepresentation = REP_ALL_NINES;

    long maximumValue;

    /**
     * Creates a custom decimal format with the supplied number of digits.
     * 
     * @param numberDigits
     */
    public CustomDecimalFormat(int numberDigits) {
        super(formatString.substring(0, numberDigits));

        maximumValue = Long.parseLong(maxString.substring(0, numberDigits));
        overflowRepresentation = REP_ALL_NINES;

        this.setMaximumIntegerDigits(numberDigits);
    }

    /**
     * Creates a custom decimal format with the supplied number of digits.
     * 
     * @param numberDigits
     * @param overflowType
     */
    public CustomDecimalFormat(int numberDigits, int overflowType) {
        super(formatString.substring(0, numberDigits));

        maximumValue = Long.parseLong(maxString.substring(0, numberDigits));
        overflowRepresentation = overflowType;

        this.setMaximumIntegerDigits(5);
    }

    @Override
    public StringBuffer format(double number, StringBuffer toAppendTo,
            FieldPosition pos) {
        if (number > maximumValue) {
            number = getOverflowRepresentation((long) number);
        }
        return super.format(number, toAppendTo, pos);
    }

    @Override
    public StringBuffer format(long number, StringBuffer toAppendTo,
            FieldPosition pos) {
        if (number > maximumValue) {
            number = getOverflowRepresentation(number);
        }
        return super.format(number, toAppendTo, pos);
    }

    private long getOverflowRepresentation(long number) {
        switch (overflowRepresentation) {
            case REP_ALL_ZEROS:
                return (0);
            default:
            case REP_ALL_NINES:
                return (maximumValue);
            case REP_TRUNCATE:
                return (number % (maximumValue + 1));
        }
    }

}