Java Development Vending Machines

1: Write a class first, including the basic properties of the commodity

 PackageCom.xt.java.base25; Public classGoods {Private intID; PrivateString name; Private intNumber ; Private DoublePrice ; /**     * @returnThe ID*/     Public intGetID () {returnID; }    /**     * @paramID The ID to set*/     Public voidSetID (intID) {ID=ID; }    /**     * @returnThe name*/     PublicString GetName () {returnname; }    /**     * @paramname the name to set*/     Public voidsetName (String name) { This. Name =name; }    /**     * @return the number*/     Public intGetNumber () {returnNumber ; }    /**     * @paramNumber the number to set*/     Public voidSetnumber (intNumber ) {         This. Number =Number ; }    /**     * @return The price*/     Public DoubleGetPrice () {returnPrice ; }    /**     * @paramPrice the price to set*/     Public voidSetprice (DoublePrice ) {         This. Price =Price ; }            }

2: Connect the database to Java and write it as a separate class, which is more convenient to use .

 PackageCom.xt.java.base25;Importjava.sql.Connection;ImportJava.sql.DriverManager;ImportJava.sql.ResultSet;Importjava.sql.SQLException;Importjava.sql.Statement; Public classGooddao {PrivateConnection Conn; PrivateStatement Stat; PrivateString url= "Jdbc:mysql://localhost:3306/lyxdatabases"; PrivateString dbdriver= "Com.mysql.jdbc.Driver"; PrivateString username= "Root"; PrivateString password= "1234"; //private construction method, only in this class can be instantiated once, in order to protect the privacy of users use this method, remember!!!     PrivateGooddao () {}Private StaticGooddao gda=NULL; /*** Write a method that obtains an instance from a method and can only be instantiated once. */         Public StaticGooddao Getgooddao () {if(gda==NULL) {Gda=NewGooddao (); }        returnGda; }         PublicConnection getconnection ()throwsexception{Try{class.forname (dbdriver); returndrivermanager.getconnection (Url,username,password); } Catch(ClassNotFoundException e) {Throw NewClassNotFoundException ("The database cannot find the driver!! "); } Catch(SQLException e) {Throw NewSQLException ("Database connection Exception!! "); }    }        //Close Connection     Public voidCloseConnection (Connection conn) {Try{            if(conn!=NULL) {conn.close (); }                    }Catch(Exception e) {System.out.println (e); }    }        //Close Statement     Public voidclosestatement (Statement stat) {Try{            if(stat!=NULL) {stat.close (); }                    }Catch(Exception e) {System.out.println (e); }    }    //Close ResultSet     Public voidCloseresultset (ResultSet rs) {Try{            if(rs!=NULL) {rs.close (); }                    }Catch(Exception e) {System.out.println (e); }    }        }

3. Main method, direct realization function

 PackageCom.xt.java.base25;Importjava.sql.Connection;ImportJava.sql.ResultSet;Importjava.sql.Statement;ImportJava.util.Scanner; Public classMain {Gooddao Gdao=Gooddao.getgooddao ();    Connection Conn;    Statement Stat;    ResultSet rs; Scanner Scanner=NewScanner (system.in); Static DoubleSummonnum; //Displays the list of goods, and the inventory requirements contain the remaining quantity for each item.      Public voidshowlist () {String SQL= "Select *from autogoods"; Try{conn=gdao.getconnection (); Stat=conn.createstatement (); RS=stat.executequery (SQL);  while(Rs.next ()) {System.out.println ("Item Number:" +rs.getstring ("id"))); System.out.print ("Product Name:" +rs.getstring ("name"))); System.out.print ("Quantity Remaining:" +rs.getint ("number"))); System.out.print ("Unit Price:" +rs.getdouble ("prices") + "\ n"); }        } Catch(Exception e) {e.printstacktrace (); }finally{Gdao.closeresultset (RS);            Gdao.closestatement (STAT);        Gdao.closeconnection (conn); }            }        //Select a product number to buy something     Public voidBuygoods () {System.out.println ("Please enter the product number you want to purchase:"); intBuyid=Scanner.nextint (); System.out.println ("Please coin:"); Summonnum=scanner.nextdouble (); System.out.println ("Your product will be shipped!!!" "); String SQL= "Update autogoods set number= (number-1) where id= '" +buyid+ "'"; String SQL1= "Select Price from Autogoods where id= '" "+buyid+" "; Try{conn=gdao.getconnection (); Stat=conn.createstatement (); RS=stat.executequery (SQL1);  while(Rs.next ()) {Summonnum=summonnum-rs.getdouble ("Price"); System.out.println ("Your change is" +summonnum); }            if(Stat.executeupdate (SQL) >0) {System.out.println ("Purchase success!! "); }        } Catch(Exception e) {//TODO auto-generated Catch blockE.printstacktrace (); }finally{Gdao.closeresultset (RS);            Gdao.closestatement (STAT);        Gdao.closeconnection (conn); }    }        //ask for further action         Public voidaskopration () { while(true) {System.out.println ("--------Please select what you need to do next-------"); System.out.println ("Continue to purchase-------1"); System.out.println ("End of purchase, change-------2"); intoperationnum=Scanner.nextint (); Switch(operationnum) { Case1: {System.out.println ("Please enter the product number you want to purchase:"); intBuyid=Scanner.nextint (); System.out.println ("Your product will be shipped!!!" "); String SQL= "Update autogoods set number= (number-1) where id= '" +buyid+ "'"; String SQL1= "Select Price from Autogoods where id= '" "+buyid+" "; Try{conn=gdao.getconnection (); Stat=conn.createstatement (); RS=stat.executequery (SQL1);  while(Rs.next ()) {Summonnum=summonnum-rs.getdouble ("Price"); if(summonnum<0) {System.out.println ("Insufficient balance, please re-select!! ");  Break ; }Else{System.out.println ("Your change is" +summonnum); if(Stat.executeupdate (SQL) >0) {System.out.println ("Purchase success!! "); }                            }                     }                }Catch(Exception e) {//TODO auto-generated Catch blockE.printstacktrace (); }finally{gdao.closestatement (stat);                Gdao.closeconnection (conn); }                 Break ; }                         Case2: {System.out.println ("will give you change, thank you for your use, look forward to your next visit ~"); System.exit (0); }            }        }    }         Public Static voidMain (string[] args) {main main=NewMain ();  while(true) {main.showlist ();        Main.buygoods ();            Main.askopration (); }    }}

Java Development Vending Machine