2022年javac编译找不到符号 .pdf

javac 编译找不到符号问题描述：javac course.java course.java:31: 找不到符号符号：类sqlBean 位置：类bean.course sqlBean db=new sqlBean ; course.java和 sqlBean.java及其他一些文件同放于bean 文件夹下course.java: package bean; import java.sql.*; public class course private String id; private String name; private String dep; private String prepare; private int mark; public void setPrepare(String s)prepare=s; public String getPrepare()return prepare; public void setMark(int s)mark=s; public int getMark()return mark; public void setDep(String s)dep=s; public String getDep()return dep; public String getId() return id; public void setId(String id) this.id = id; public String getName() return name; 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 1 页，共 7 页 - - - - - - - - - public void setName(String name) this.name = name; public ResultSet getPrepares() / 得到所能选择的预修课String sql=select name,id from course ; sqlBean db = new sqlBean(); ResultSet rs = db.executeQuery(sql); return rs; public String getPrepareDep() /察看预修课所在系String s=no; String sql=select dep from course where id= prepare ; sqlBean db = new sqlBean(); try ResultSet rs = db.executeQuery(sql); if(rs.next() s=rs.getString(dep); catch(Exception e) e.getMessage(); return s; public ResultSet getCourse() /察看所有课程String sql=select * from course ; sqlBean db= new sqlBean(); ResultSet rs = db.executeQuery(sql); return rs; public int deleteCourse(String id) int num=0; String sql=delete from Course where id = id ; sqlBean db= new sqlBean(); num=db.executeDelete(sql); 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 2 页，共 7 页 - - - - - - - - - return num; public String getPrepareDep(String id) String dep=; String sql=select dep from course where id= id ; sqlBean db= new sqlBean(); try ResultSet rs = db.executeQuery(sql); if(rs.next() dep=rs.getString(dep); catch(SQLException e)System.out.print(e.toString(); return dep; public void updateCourse(String id) String sql=update course set name= name ,prepare= prepare , dep= dep ,mark= mark where id= id ; sqlBean db= new sqlBean(); db.executeInsert(sql); public void addCourse() String sql=insert into course(id,name,mark,prepare,dep) VALUES ( id , name , mark , prepare , dep ) ; sqlBean db = new sqlBean(); db.executeInsert(sql); public boolean hasLogin( String id) boolean f=true; String sql=select id from course where id= id ; sqlBean db = new sqlBean(); try 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 3 页，共 7 页 - - - - - - - - - ResultSet rs =db.executeQuery(sql); if(rs.next() f=false; catch(Exception e) e.getMessage(); return f; sqlBean.java: package bean; import java.io.*; import java.sql.*; public class sqlBean/ public Connection conn=null; public ResultSet rs=null; private String DatabaseDriver=sun.jdbc.odbc.JdbcOdbcDriver; /DataSource 数据源名称DSN private String DatabaseConnStr=jdbc:odbc:ClassDB2,sa,; /定义方法/*setXxx 用于设置属性值;getXxx 用于得到属性值*/ public void setDatabaseDriver(String Driver) this.DatabaseDriver=Driver; public String getDatabaseDriver() return (this.DatabaseDriver); public void setDatabaseConnStr(String ConnStr) this.DatabaseConnStr=ConnStr; public String getDatabaseConnStr() return (this.DatabaseConnStr); 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 4 页，共 7 页 - - - - - - - - - public sqlBean()/ 构造函数try Class.forName(DatabaseDriver); catch(java.lang.ClassNotFoundException e) System.err.println(加载驱动器有错误: e.getMessage( ); System.out.print(执行插入有错误: e.getMessage();/输出到客户端 public int executeInsert(String sql) int num=0; try conn = DriverManager.getConnection(jdbc:odbc:ClassDB,sa,); Statement stmt=conn.createStatement( ); num=stmt.executeUpdate(sql); catch(SQLException ex) System.err.println(执行插入有错误: ex.getMessage() ); System.out.print(执行插入有错误: ex.getMessage();/输出到客户端 CloseDataBase(); return num; / display data public ResultSet executeQuery(String sql) rs=null; try conn = DriverManager.getConnection(jdbc:odbc:ClassDB,sa,); Statement stmt=conn.createStatement( ); rs=stmt.executeQuery(sql); 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 5 页，共 7 页 - - - - - - - - - catch(SQLException ex) System.err.println(执行查询有错误: ex.getMessage() ); System.out.print(执行查询有错误: ex.getMessage(); /输出到客户端 return rs; / delete data public int executeDelete(String sql) int num=0; try conn = DriverManager.getConnection(jdbc:odbc:ClassDB,sa,); Statement stmt=conn.createStatement( ); num=stmt.executeUpdate(sql); catch(SQLException ex) System.err.println(执行删除有错误: ex.getMessage() ); System.out.print(执行删除有错误: ex.getMessage(); /输出到客户端 CloseDataBase(); return num; / public void CloseDataBase() try conn.close(); catch(Exception end) System.err.println(执行关闭Connection 对象有错误： end.getMessage( ) ); System.out.print(执行执行关闭Connection对象有错误：有错误: end.getMessage(); / 输出到客户端 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 6 页，共 7 页 - - - - - - - - - 到 bean文件夹所在目录去编译：javac bean/course.java 或者javac bean/*.java 因为 package 写着是bean 那这两个文件就应该在bean文件夹下面。运行也一样在bean所在文件夹：java bean.course 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 7 页，共 7 页 - - - - - - - - -