In order to highlight odd or even rows with a background color, in JasperReports, first create a rectangle element with a background of your color choice, and send it to the background (in JasperAssistant, right click on the rectangle, choose Arrange and then Send to Back). Second, use the following expression to set when the element should appear, by placing the expression in the Print When Expression field of the rectangle element. Where the $V{PAGE_COUNT} appears, you can use that, to base it on the row number on the page, or use $V{REPORT_COUNT} to base it on the row within the report. Also, if you are using a group, you can use $V{groupname_COUNT} where groupname is replaced with the name of your group. The expression below will then test the row number within the Page, Report, or Group (whichever you selected) and if its divisible by 2, it will display the rectangle element with the background color.

new Boolean( $V{PAGE_COUNT}.intValue() % 2 ==0 )