java java分页实用程序
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java paging util
提问by Alstresh
I have List of Object. I need to do pagination.
The input parameters are the maximum number object per Page and Page number.
我有对象列表。我需要做分页。
输入参数是每页的最大数量对象和页码。
For example input list = ("a", "b", "c", "d", "e", "f")
The maximum number per Page is 2
Page number is 2
Result = ("c", "d")
例如输入 每页list = ("a", "b", "c", "d", "e", "f")
的最大数量为 2 页数为 2 结果 = ("c", "d")
Are there any ready-made classes(libs) to do this? For example Apache project or so on.
有没有现成的类（库）来做到这一点？例如Apache项目等等。
回答by Christian Kuetbach
int sizePerPage=2;
int page=2;
int from = Math.max(0,page*sizePerPage);
int to = Math.min(list.size(),(page+1)*sizePerPage)
list.subList(from,to)
回答by Walery Strauch
With Java 8 steams:
使用 Java 8 蒸汽：
list.stream()
.skip(page * size)
.limit(size)
.collect(Collectors.toCollection(ArrayList::new));
回答by hsz
Try with:
尝试：
int page = 1; // starts with 0, so we on the 2nd page
int perPage = 2;
String[] list = new String[] {"a", "b", "c", "d", "e", "f"};
String[] subList = null;
int size = list.length;
int from = page * perPage;
int to = (page + 1) * perPage;
to = to < size ? to : size;
if ( from < size ) {
subList = Arrays.copyOfRange(list, from, to);
}
回答by Lucas Pires
Simple method
简单的方法
public static <T> List<T> paginate(Page page, List<T> list) {
int fromIndex = (page.getNumPage() - 1) * page.getLenght();
int toIndex = fromIndex + page.getLenght();
if (toIndex > list.size()) {
toIndex = list.size();
}
if (fromIndex > toIndex) {
fromIndex = toIndex;
}
return list.subList(fromIndex, toIndex);
}
回答by Averroes
Try this:
试试这个：
int pagesize = 2;
int currentpage = 2;
list.subList(pagesize*(currentpage-1), pagesize*currentpage);
This code returns a list with only the elements you want (a page).
此代码返回一个仅包含您想要的元素的列表（一个页面）。
You should check the index also to avoid java.lang.IndexOutOfBoundsException.
您还应该检查索引以避免 java.lang.IndexOutOfBoundsException。
回答by Amit Deshpande
As per your question simple List.subListwill give you expected behaviour
size()/ 2= number of pages
根据您的问题 simpleList.subList会给您预期的行为 size()/ 2= 页数
回答by Reimeus
You could use List.subListusing Math.minto guard against ArrayIndexOutOfBoundsException:
您可以使用List.subListusingMath.min来防范ArrayIndexOutOfBoundsException：
List<String> list = Arrays.asList("a", "b", "c", "d", "e");
int pageSize = 2;
for (int i=0; i < list.size(); i += pageSize) {
System.out.println(list.subList(i, Math.min(list.size(), i + pageSize)));
}
