org.apache.commons.lang3.math.NumberUtils#LONG_ZERO源码实例Demo

/**
 * 文字と数字の混ざった文字列から、数字のみを取り出してLongを作成します。
 * 主に、外部で採番されたIDから数字のIDを作成するために使用します。
 *
 * @param stringWithNumber
 * @return
 */
public static Long extractNumberString(Long headerNumber, String stringWithNumber) {
    StringBuilder sb = new StringBuilder(30);
    if (headerNumber != null) {
        sb.append(headerNumber.longValue());
    }

    for (int i = 0; i < stringWithNumber.length(); i++) {
        if (CharUtils.isAsciiNumeric(stringWithNumber.charAt(i))) {
            sb.append(stringWithNumber.charAt(i));
        }
    }

    if (sb.length() == 0) {
        return NumberUtils.LONG_ZERO;
    } else if(sb.length() >= 19) {
        // 19桁以上の場合は先頭の18文字を使用する
        return Long.valueOf(sb.substring(0, 18));
    } else {
        return Long.valueOf(sb.toString());
    }
}
 

/**
 * Compares the {@code quantityOnStock} values of an {@link InventoryEntry} and an {@link InventoryEntryDraft}
 * and returns an {@link Optional} of update action, which would contain the {@code "changeQuantity"}
 * {@link UpdateAction}. If both {@link InventoryEntry} and {@link InventoryEntryDraft} have the same
 * {@code quantityOnStock} values, then no update action is needed and empty optional will be returned.
 * If the {@code quantityOnStock} from the {@code newEntry} is {@code null}, the new {@code quantityOnStock} will
 * have a value of 0L.
 *
 * @param oldEntry the inventory entry that should be updated
 * @param newEntry the inventory entry draft which contains new quantity on stock
 * @return optional containing update action or empty optional if quantities on stock are identical
 */
@Nonnull
public static Optional<UpdateAction<InventoryEntry>> buildChangeQuantityAction(@Nonnull final InventoryEntry
                                                                                       oldEntry,
                                                                               @Nonnull final InventoryEntryDraft
                                                                                   newEntry) {
    final Long oldQuantityOnStock = oldEntry.getQuantityOnStock();
    final Long newQuantityOnStock = newEntry.getQuantityOnStock() == null ? NumberUtils.LONG_ZERO : newEntry
        .getQuantityOnStock();
    return buildUpdateAction(oldQuantityOnStock, newQuantityOnStock, () -> ChangeQuantity.of(newQuantityOnStock));
}