打不开nc,提示信息是java.sql.SQLException:Listener refused the connection wit我安装的是oracle数据库。具体的提示信息如下：java.sql.SQLException:Listener refused the connection with the following error:ORA—12505，TNS：List

打不开nc,提示信息是java.sql.SQLException:Listener refused the connection wit我安装的是oracle数据库。具体的提示信息如下：java.sql.SQLException:Listener refused the connection with the following error:ORA—12505，TNS：List java.lang.NullPointerException错误是什么意思安卓APP的错误提示是java.lang.NullPointerException,这是一个什么错误呢?更多信息见图.谢谢java.lang.NullPointerException at goldendawn.getimei.ui.MainActivity$13.onClick(MainAct java.sql.time java.sql.date 二者如何组合成一个java.util.date 初学java,写了一个链接Oracle的小程序,运行后报错：java.sql.SQLException:无效的列索引请问这是为什么?附上程序：package connection;import java.sql.*;public class Connectionb { public static final void main(String args[] java.sql.Date与java.util.Date的区别 Java 如何根据现在的时间毫秒来计算时间的公式(不想用原有的类)java.sql.Timestamp time ;long tt = -1 ;time = new java.sql.Timestamp(new java.util.Date().getTime());tt = time.getTime()来获得信息.我希望可以根据一些 import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.sql.*; public class a java.sql.date的时分秒去哪里了? java.sql.date的时分秒去哪里了? java.sql.SQLException: Illegal operation on empty result set.import java.sql.Connection;import java.sql.ResultSet;import java.sql.Statement;public class shujuku { public static void main(String args[]) { Connection conn; conn = Conn 具体信息如下：java.sql.SQLException:Listener refused the connection with the following error:ORA—12505,TNS：Listener dose not currentlly kown of SID given in connect descriptor the connection description used by client was 127.0.0.1:1521:yx java如何获取当前时间 年月日 时分秒并且转成java.sql.Date格式.谢谢你们 import=java.sql.*和import=java.util.* 有什么区别? java 中import java.sql.Connection 报错：The import java.sql.Connection conflicts with a type defined in the same file “NC”是啥意思? nc是撒? 异常:java.lang.IllegalStateException怎么解决?java.lang.IllegalStateExceptionat servlet.zhuce.doGet(zhuce.java:48)at servlet.zhuce.doPost(zhuce.java:77)提示这两行有问题以下是servlet代码:public class zhuce extends HttpServlet {privat import java.io.IOException;import java.io.OutputStream;import java.net.Socket;import java.net.UnknownHostException;import java.sql.ResultSet;import org.sql.IntoDB;public class BaiduReferer {public static void main(String[] args) throws UnknownHostExc