java list 的分页

import java.util.Collections;
import java.util.List;




public class ListPageUtil {
/**
* 每页显示条数
*/
private int pageSize;


/**
* 总页数
*/
private int pageCount;


/**
* 原集合
*/
private List data;


public ListPageUtil(List data, int pageSize) {
if (data == null || data.isEmpty()) {
throw new IllegalArgumentException("data must be not empty!");
}


this.data = data;
this.pageSize = pageSize;
this.pageCount = data.size() / pageSize;
if (data.size() % pageSize != 0) {
this.pageCount++;
}
}


/**
* 得到分页后的数据
*
* @param pageNum
*            页码
* @return 分页后结果
*/
public List getPagedList(int pageNum) {
int fromIndex = (pageNum - 1) * pageSize;
if (fromIndex >= data.size()) {
return Collections.emptyList();
}


int toIndex = pageNum * pageSize;
if (toIndex >= data.size()) {
toIndex = data.size();
}
return data.subList(fromIndex, toIndex);
}


public int getPageSize() {
return pageSize;
}


public List getData() {
return data;
}


public int getPageCount() {
return pageCount;
}


}