看看这个分页问题在哪实在看不出

jiajv 2006-10-12 08:47:41

import org.apache.log4j.Logger;

import java.util.List;

/**
* @author
*/
public class ListPage implements Page {

private List elements;
private int pageSize;
private int pageNumber;

/**
* Construct a new ListPage. ListPage numbers are zero-based, so the
* first page is page 0.
*
* @param pageNumber the page number (zero-based);
* if Integer.MAX_VALUE will return the last page for the query
* @param pageSize the number of results to display on the page
*/
public ListPage(List elements, int pageNumber, int pageSize) {
this.elements = elements;
this.pageSize = pageSize;
this.pageNumber = pageNumber;
if (Integer.MAX_VALUE == this.pageNumber)
this.pageNumber = (getTotalNumberOfElements() / this.pageSize);
}

public boolean isFirstPage() {
return getPageNumber() == 0;
}

public boolean isLastPage() {
return getPageNumber() >= getLastPageNumber();
}

public boolean hasNextPage() {
return ((getPageNumber() + 1) * getPageSize()) <
(getTotalNumberOfElements() + 1);
}

public boolean hasPreviousPage() {
return getPageNumber() > 0;
}

public int getLastPageNumber() {
/*
* We use the Math.floor() method because page numbers are zero-based
* (i.e. the first page is page 0).
*/
double totalResults = new Integer(getTotalNumberOfElements()).doubleValue();
return new Double(Math.floor(totalResults / getPageSize())).intValue();
}
//测试此方法 list 有元素可是size()==0
public List getThisPageElements() {
/*
* Since we retrieved one more than the specified pageSize when the
* class was constructed, we now trim it down to the pageSize if a next
* page exists.
*/
final int start = getPageNumber() * getPageSize();
return elements.subList(Math.min(start, getTotalNumberOfElements() + 1),
Math.min(start + getPageSize(), getTotalNumberOfElements() + 1));
//这个方法有问题有记录可size==○啊
}

public Logger getLogger() {
return Logger.getLogger(this.getClass());
}

/**
* this is 0-based, differently from list.size();
*/
public int getTotalNumberOfElements() {
return elements.size() - 1;
}

public int getThisPageFirstElementNumber() {
return getPageNumber() * getPageSize() + 1;
}

public int getThisPageLastElementNumber() {
int fullPage = getThisPageFirstElementNumber() + getPageSize() - 1;
return getTotalNumberOfElements() < fullPage ?
getTotalNumberOfElements() :
fullPage;
}

public int getNextPageNumber() {
return getPageNumber() + 1;
}

public int getPreviousPageNumber() {
return getPageNumber() - 1;
}

public int getPageSize() {
return pageSize;
}

public int getPageNumber() {
return pageNumber;
}

}

getThisPageElements这个方法有问题有记录可是size是0啊高手给看看改好啊

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