Apologize for my Chinese English.
i made a demo.
the list contains 3 data and can show in one page.
if i design template like this, it will show in one page.
if i design template like this.it will show in two pages, and the second page is blank.the height of detail band is same as paper's height.
i found the answer after searched with google for a long time.
i thinked i used list element in a wrong way.
properties of jasperreports list element have settings of cell height and cell width.i set the properity to be equal to the size of jasperreports list element first and it go wrong.
settings of jasperreports list element
this is the website i found answer.