public static File createTempFile(){
  File tempFile;
  try {
    tempFile=File.createTempFile("cqengine_",".db");
  }
 catch (  Exception e) {
    throw new IllegalStateException("Failed to create temp file for CQEngine disk persistence",e);
  }
  return tempFile;
}

public static File createTempFile ( ) { File tempFile ; try { tempFile = File . createTempFile ( "cqengine_" , ".db" ) ; } catch ( Exception e ) { throw new IllegalStateException ( "Failed to create temp file for CQEngine disk persistence" , e ) ; } return tempFile ; }
creates a new unique temp file in the jvm temp directory which can be used for persistence .
