以下程序没有抛出任何异常,可就是输出con is null 这是什么情况啊？

Question

import java.sql.*;public class DBConnection {private static Connection con;public static Connection getMySQLConnection() {try {Class.forName("com.mysql.jdbc.Driver");Connection con = DriverManager.getConnection("jdbc:mysql://localhost/ray", "root", "root");}catch(ClassNotFoundException e) {System.out.println("Sorry, you get a ClassNotFoundException");}catch(SQLException e) {System.out.println("Sorry, you get a SQLException");}if (con == null) {System.out.println("con is null");}return con;}}

Answer 1

private static Connection con; 这里定义了一个con
public static Connection getMySQLConnection() {
try {
Class.forName("com.mysql.jdbc.Driver");
这里又定义了一个con,它在try的范围内有效，出了try就没效了。
Connection con = DriverManager.getConnection(
"jdbc:mysql://localhost/ray", "root", "root");

Answer 2

private static Connection con;
Connection con = 。。。
重新声明了。
里面的 con = ..