The Preview Feature of JasperAssistant can consume a significant amount of memory depending on the size of your reports. It is recommended that you increase the default memory settings used when running Eclipse. The following line starts Eclipse with 512M for its memory allocation pool:
eclipse -vmargs -Xmx512m
When using a Sun VM, you may also need to increase the size of the permanent generation memory. The default maximum is 64 megabytes, but more may be needed depending on your plug-in configuration and use. The maximum permanent generation size is increased using the following command line:
eclipse -vmargs -XX:MaxPermSize=128