ListUtil集合操作常用方法类

 * 集合操作常用方法类.
 * <p>
 *
 * @author 柯
 */
public class ListUtil {

    /**
     * 判断List不为空,非空返回true,空则返回false
     *
     * @param list
     * @return boolean
     */
    public static boolean isNotNull(List<?> list) {

        if (null != list) {
            if ((list.size() > 0) && !list.isEmpty()) {
                return true;
            }
        }
        return false;
    }

    /**
     * 判断List是为空,为空返回true,非空则返回false
     *
     * @param list
     * @return boolean
     */
    public static boolean isNull(List<?> list) {

        if (null == list || list.size() == 0 || list.isEmpty()) {
            return true;
        }
        return false;
    }

    /**
     *
     * @Title: removeDuplist @date 2016年7月17日 下午3:55:38 @Description:
     * 去除集合中重复的内容 @param list @return @throws
     */
    public static List<String> removeDuplist(List<String> list) {
        if (list != null && list.size() > 0) {
            HashSet<String> hashSet = new HashSet<String>(list);
            list.clear();
            list.addAll(hashSet);
        }
        return list;
    }

    /**
     *
     * @Title: removeDuplistInt @date 2016年7月18日 下午5:16:04 @Description:
     * 去除重复的值 @param list @return @throws
     */
    public static List<Integer> removeDuplistInt(List<Integer> list) {
        if (list != null && list.size() > 0) {
            HashSet<Integer> hashSet = new HashSet<Integer>(list);
            list.clear();
            list.addAll(hashSet);
        }
        return list;
    }

    /**
     *
     * @Title: getCurveValue @date 2016年8月16日 下午4:48:33 @Description:
     * 计算集合中的最大值和最小值， 返回改后的最大值，间隔，最小值 @param list @return @throws
     */
    public static List<Long> getCurveValue(List<Long> list) {
        List<Long> curveList = new ArrayList<Long>();

        Long maxValue = 0l;// 集合中最大值
        Long avgValue = 0l;// 间隔值
        Long minValue = 0l;// 最小值

        if (ListUtil.isNotNull(list)) {
            maxValue = Collections.max(list) / 100;
        }

        if (maxValue > 10000) {
            maxValue += 1000;
        } else if (maxValue > 1000) {
            maxValue += 300;
        } else if (maxValue > 100) {
            maxValue += 50;
        } else if (maxValue > 10) {
            maxValue += 5;
        } else {
            maxValue = 10l;
        }

        avgValue = maxValue / 5;

        curveList.add(maxValue);
        curveList.add(avgValue);
        curveList.add(minValue);

        return curveList;
    }

    /**
     * list集合深度复制
     * @param src
     * @return
     * @throws IOException
     * @throws ClassNotFoundException
     */
    public static <T> List<T> deepCopy(List<T> src) throws IOException, ClassNotFoundException {
        ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
        ObjectOutputStream out = new ObjectOutputStream(byteOut);
        out.writeObject(src);  

        ByteArrayInputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());
        ObjectInputStream in = new ObjectInputStream(byteIn);
        @SuppressWarnings("unchecked")
        List<T> dest = (List<T>) in.readObject();
        return dest;
    }  

    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        for (int i = 0 ; i < 19; i++) {
            list.add("aa" + i);
        }
        int d = list.size() / 13;
        int q = list.size() % 13;
        if (q > 0)
            d += 1;

        List<List<String>> datas = new ArrayList<List<String>>(d);
        if (d == 1) {
            datas.add(list);
        } else if (d > 1){
            for (int k = 0; k < d; k ++) {
                List<String> sub_a = new ArrayList<String>();
                if (k == d - 1)
                    sub_a = list.subList(k * 13, list.size());
                else
                    sub_a = list.subList(k * 13, (k + 1) * 13);

                datas.add(sub_a);
            }
        }

        System.out.println(d);
        for (List<String> obj : datas) {
            List<String> data =  obj;
            for (String c : data) {
                System.out.println(c);
            }
        }
    }

    /**
     * 获取列表总页数
     */
    public static <T> int getListPages(List<T> list,int pageNum,int pageSize ){
        if (isNull(list)){
            return 0;
        }
        BaseQuery baseQuery=new BaseQuery();
        baseQuery.setPageNum(pageNum);
        baseQuery.setPageSize(pageSize);
        //list的大小
        int total = list.size();
        baseQuery.setTotal(total);
        return baseQuery.getPages();
    }

    /**
     * 对列表进行分页,索引左边包括，右边不包括
     */
    public static <T> List<T> subListByPage(List<T> list,int pageNum,int pageSize ){
        if (isNull(list)){
            return Collections.emptyList();
        }
        BaseQuery baseQuery=new BaseQuery();
        baseQuery.setPageNum(pageNum);
        baseQuery.setPageSize(pageSize);
        //list的大小
        int total = list.size();
        //对list进行截取
        return list.subList(baseQuery.getStartPosition(),total-baseQuery.getStartPosition()>baseQuery.getPageSize()?baseQuery.getStartPosition()+baseQuery.getPageSize():total);
    }

    /**
     * 对列表进行索引截取,索引左边包括，右边不包括
     */
    public static <T> List<T> subListByPosition(List<T> list,BaseQuery baseQuery){

        if (isNull(list)){
            baseQuery.setTotal(0);
            return Collections.emptyList();
        }
        //设置列表总条数
        int total = list.size();
        baseQuery.setTotal(total);

        if ((baseQuery.getStartIndex()-1)>=total){
            return Collections.emptyList();
        }
        //从0开始 --> 1
        if (baseQuery.getStartIndex()==0){
            baseQuery.setStartIndex(1);
        }
        //对list进行截取
        return list.subList(baseQuery.getStartIndex()-1,baseQuery.getEndIndex()>total?total:baseQuery.getEndIndex());
    }

    /**
     *对列表字段进行比较排序
     */
    public static <T> void sortByField(List<T> dtoList,String fieldName,String order) {
        int compare=1;
        if ("desc".equals(order)){
            compare=-1;
        }
        int finalCompare = compare;

        Collections.sort(dtoList, new Comparator<T>() {
            @Override
            public int compare(T o1, T o2) {
                PropertyDescriptor pd1 = null;
                PropertyDescriptor pd2 = null;
                Object value1 =null;
                Object value2 =null;
                try {
                    pd1 = new PropertyDescriptor(fieldName, o1.getClass());
                    value1 = pd1.getReadMethod().invoke(o1, null);

                    pd2 = new PropertyDescriptor(fieldName, o2.getClass());
                    value2 = pd2.getReadMethod().invoke(o2, null);

                } catch (IntrospectionException e) {
                    e.printStackTrace();
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                } catch (InvocationTargetException e) {
                    e.printStackTrace();
                }

                 if (value1.getClass().equals(Double.class)){
                    if ((Double)value1 > (Double)value2) {
                        return finalCompare;
                    } else if ((Double)value1 < (Double)value2) {
                        return -finalCompare;
                    }
                }else if (value1.getClass().equals(Integer.class)){
                    if ((Integer)value1 > (Integer)value2) {
                        return finalCompare;
                    } else if ((Integer)value1 < (Integer)value2) {
                        return -finalCompare;
                    }
                }
                return 0;
            }
        });
    }

}