学习马士兵老师的网上商城项目，但是向mysql插入时间是报错，求解答

public void save() {
Connection conn = DB.getConnection();
String sql = "insert into user values (null, ?, ?, ?, ?, ?)";
PreparedStatement pstmt = DB.prepareStatement(conn, sql);
try {
pstmt.setString(1, username);
pstmt.setString(2, password);
pstmt.setString(3, phone);
pstmt.setString(4, addr);
pstmt.setTimestamp(5, new Timestamp(rdate.getTime()));
pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
}

下面是报错：
com.mysql.jdbc.MysqlDataTruncation: Data truncation: Incorrect datetime value: '' for column 'rdate' at row 1
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2973)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1600)
at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1125)
at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:677)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:794)
at com.leizong.shopping.User.save(User.java:63)
at org.apache.jsp.register_jsp._jspService(register_jsp.java:131)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)

at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2503)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2492)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)