大家好我是java新手，我正试图让这个java代码运行但是由于某些原因它没有在我的Eclipse控制台中显示错误..它确实在这一行有语法错误：
b.addActionListener (new ActionListener() {
我已经尝试了所有的建议而且我没有得到任何地方..我知道这很简单，但我从未让控制台之前没有显示任何错误。谢谢你的帮助！
import javax.swing.*;
import java.awt.event.*;
import java.sql.*;
public class Loging {
Connection con;
Statement st;
ResultSet rs;
JFrame f = new JFrame("User Login");
JLabel l = new JLabel("Username");
JLabel l1 = new JLabel("password");
JTextField t = new JTextField(10);
JTextField t1 = new JTextField(10);
JButton b = new JButton("Login");
public static void main(String[] args) {
// TODO Auto-generated method stub
}
public void Loging1() {
connect();
frame();
}
public void connect() {
try {
String driver = "sun.jdbc.odbc.JdbcOdbcDriver";// Driver needed for
// connection
Class.forName(driver);// Class.forName(driver);
String db = "jdbc:odbc:db1";
con = DriverManager.getConnection(db);
st = con.createStatement();
} catch (Exception ex) {
}
}
public void frame()
{
f.setSize (600,400);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
JPanel p = new JPanel();
p.add(l);
p.add(t);
p.add(l1);
p.add(t1);
p.add(b);
f.add(p);
b.addActionListener (new ActionListener() {
}
public void actionPerformed(ActionEvent e) {
try {
String user = t.getText().trim();
String pass = t1.getText().trim();
String sql = "select user, pass from Table1 where user = '" + user
+ "'and pass = '" + pass + "'";// for sql query
// String sql =
// "select user, pass from Table1 where user = '"+user+"'pass = '"+pass+"'";
// Getting the fields user and pass checks tthat both are equal to
// each orther
rs = st.executeQuery(sql);// executes query
int count = 0;// cont the rows for the query
while (rs.next()) {
count = count + 1;// if no rows are returned then no user exist,
// if count is = to 1 then user exist }
}
if (count == 1)// if = to 1 user exist
{
JOptionPane.showMessageDialog(null, "Logged in!");
} else if (count > 1)// if more that one
{
JOptionPane.showMessageDialog(null, "Duplicate user, DENIED!");
}
else {
JOptionPane.showMessageDialog(null, "user not found");
}
} catch (Exception ex) {
}
// public static void main(String[] args) {
}
// New Loging1 ();
}
答案 0 :(得分：2)
此...
b.addActionListener (new ActionListener() {
}
会给你一个编译器错误，因为你未能满足ActionListener接口的要求，即实现actionPerformed方法。
更像是......
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class Loging {
Connection con;
Statement st;
ResultSet rs;
JFrame f = new JFrame("User Login");
JLabel l = new JLabel("Username");
JLabel l1 = new JLabel("password");
JTextField t = new JTextField(10);
JTextField t1 = new JTextField(10);
JButton b = new JButton("Login");
public static void main(String[] args) {
// TODO Auto-generated method stub
}
public void Loging1() {
connect();
frame();
}
public void connect() {
try {
String driver = "sun.jdbc.odbc.JdbcOdbcDriver";//Driver needed for connection
Class.forName(driver);// Class.forName(driver);
String db = "jdbc:odbc:db1";
con = DriverManager.getConnection(db);
st = con.createStatement();
} catch (Exception ex) {
}
}
public void frame() {
f.setSize(600, 400);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
JPanel p = new JPanel();
p.add(l);
p.add(t);
p.add(l1);
p.add(t1);
p.add(b);
f.add(p);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
String user = t.getText().trim();
String pass = t1.getText().trim();
String sql = "select user, pass from Table1 where user = '" + user + "'and pass = '" + pass + "'";//for sql query
//String sql = "select user, pass from Table1 where user = '"+user+"'pass = '"+pass+"'";
//Getting the fields user and pass checks tthat both are equal to each orther
rs = st.executeQuery(sql);//executes query
int count = 0;//cont the rows for the query
while (rs.next()) {
count = count + 1;//if no rows are returned then no user exist, if count is = to 1 then user exist }
}
if (count == 1)//if = to 1 user exist
{
JOptionPane.showMessageDialog(null, "Logged in!");
} else if (count > 1)//if more that one
{
JOptionPane.showMessageDialog(null, "Duplicate user, DENIED!");
} else {
JOptionPane.showMessageDialog(null, "user not found");
}
} catch (Exception ex) {
}
//public static void main(String[] args) {
}
// New Loging1 ();
});
}
}
至少会编译（抱歉，还有一些我不想进入的其他格式问题）
您还应该了解如何使用PreparedStatements查看Using Prepared Statements了解更多详情，它们通常更灵活，更安全。
JdbcOdbcDriver已弃用，您不应使用它。像UCanAccess这样的东西可能是更合适的解决方案，但您需要做一些研究