java 开发中常用方法

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从List中拿出top指的条数数据：

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/**     * 取top x条产品类数据     *     * @param sourList  产品类集合     * @param rowsCount 条数     * @return List<ProductInfo>     */    public static List<ProductInfo> limitProductInfoList(List<ProductInfo> sourList,                                                         int rowsCount) {        List<ProductInfo> tempList = new ArrayList<>();        if (sourList != null) {            int sourListSize = sourList.size();            if (rowsCount < sourListSize) {                int subCount =                        sourListSize % rowsCount == 0 ? sourListSize / rowsCount : sourListSize / rowsCount + 1;                int startIndext = 0;                int stopIndext = 0;                for (int i = 0; i < subCount; i++) {                    stopIndext =                            (i == subCount - 1) ? stopIndext + sourListSize % rowsCount : stopIndext + rowsCount;                    tempList = new ArrayList<ProductInfo>(sourList.subList(startIndext, stopIndext));                    startIndext = stopIndext;                    if (tempList.size() > 0) {                        break;                    }                }            } else {                tempList = sourList;            }        }        return tempList;    }

比较字符串是否在数组中：

 private static String[] StarArray = new String[]{"DHTL", "IHTL", "GPKG", "GDIY", "GCRU"};ArrayUtils.contains(StarArray, "DHTL")

//验证对象为null

if (ObjectUtils.equals(sysRole, null)) {    sysRole = this.getRole(systemCode, loginName);}

//验证List

if (CollectionUtils.isNotEmpty(sysRoleList)) {    sysRole = sysRoleList.get(0);}

//验证字符串-验证时候忽略空白

if (StringUtils.isBlank(formData.getPost()))｛｝

//验证字符串非空

if (StringUtils.isNotEmpty(userCard.getUID()))

/**     * 清除空白字符     *     * @param str     * @return     */    public static String trimAllWhitespace(String str) {        if (str != null) {            int len = str.length();            if (len > 0) {                char[] dest = new char[len];                int destPos = 0;                for (int i = 0; i < len; ++i) {                    char c = str.charAt(i);                    if (!Character.isWhitespace(c)) {                        dest[destPos++] = c;                    }                }                return new String(dest, 0, destPos);            }        }        return str;    }    /**     *list转换string     * @param list  List<String>     * @param separator 分隔符 逗号等     * @return     */    public static String listToString(List<String> list, char separator) {        return org.apache.commons.lang.StringUtils.join(list.toArray(), separator);    }    /**     *string转换list     * @param str 分隔符字符串     * @param separator  逗号等     * @return  List<String>     */    public static List<String> stringToList(String str, String separator) {        return java.util.Arrays.asList(str.split(separator));    }阅读原文http://click.aliyun.com/m/34920/

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