Exception in thread "main" java.sql.SQLException: Access denied for user ''@'localhost' (using password: NO)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)

at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)

at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1710)

at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)

at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2191)

at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2222)

at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2017)

at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:779)

at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

at java.lang.reflect.Constructor.newInstance(Unknown Source)

at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)

at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:389)

at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)

at java.sql.DriverManager.getConnection(Unknown Source)

at java.sql.DriverManager.getConnection(Unknown Source)

at jdbc_imooc.CKXa.main(CKXa.java:19)