import java.util.*;
import java.awt.*;
import java.io.*;
import java.net.*;
import java.sql.*;
import java.awt.event.*;
import javax.swing.*;
class Delbookfrm extends JFrame implements ActionListener
{
JLabel l_bookname;
JTextField t_bookname;
JButton b_delbook,b_back;
JPanel pan1,pan2,pan3;
NetConn sql;
Statement sqll;
Delbookfrm()
{
//界面布局
l_bookname=new JLabel("输入你要删除的书籍的名称:");
t_bookname=new JTextField("",10);
b_delbook=new JButton("删除");
b_back=new JButton("返回");
b_delbook.addActionListener(this);
b_back.addActionListener(this);
pan1=new JPanel();pan2=new JPanel();pan3=new JPanel();
pan1.add(l_bookname);pan2.add(t_bookname);pan3.add(b_delbook);pan3.add(b_back);
setLayout(new GridLayout(3,1));
add(pan1);add(pan2);add(pan3);
setBounds(400,300,300,350);
//建立数据库连接
sql=new NetConn();
}
public void actionPerformed(ActionEvent ed)
{
//单击删除按钮的事件处理程序
if(ed.getSource()==b_delbook)
{
try
{
sqll=sql.connect();
//根据给定图书信息将其从数据库中删除
sqll.executeUpdate("delete from books where bookname="+"'"+t_bookname.getText()+"'");
l_bookname.setText("书籍删除成功");
}
catch(SQLException e6)
{}
}
else if(ed.getSource()==b_back)
{
dispose();
}
}
}
运行后提示 java.lang.NoSuchMethodError: main Exception in thread "main" ,请问这是怎么回事
import java.awt.*;
import java.io.*;
import java.net.*;
import java.sql.*;
import java.awt.event.*;
import javax.swing.*;
class Delbookfrm extends JFrame implements ActionListener
{
JLabel l_bookname;
JTextField t_bookname;
JButton b_delbook,b_back;
JPanel pan1,pan2,pan3;
NetConn sql;
Statement sqll;
Delbookfrm()
{
//界面布局
l_bookname=new JLabel("输入你要删除的书籍的名称:");
t_bookname=new JTextField("",10);
b_delbook=new JButton("删除");
b_back=new JButton("返回");
b_delbook.addActionListener(this);
b_back.addActionListener(this);
pan1=new JPanel();pan2=new JPanel();pan3=new JPanel();
pan1.add(l_bookname);pan2.add(t_bookname);pan3.add(b_delbook);pan3.add(b_back);
setLayout(new GridLayout(3,1));
add(pan1);add(pan2);add(pan3);
setBounds(400,300,300,350);
//建立数据库连接
sql=new NetConn();
}
public void actionPerformed(ActionEvent ed)
{
//单击删除按钮的事件处理程序
if(ed.getSource()==b_delbook)
{
try
{
sqll=sql.connect();
//根据给定图书信息将其从数据库中删除
sqll.executeUpdate("delete from books where bookname="+"'"+t_bookname.getText()+"'");
l_bookname.setText("书籍删除成功");
}
catch(SQLException e6)
{}
}
else if(ed.getSource()==b_back)
{
dispose();
}
}
}
运行后提示 java.lang.NoSuchMethodError: main Exception in thread "main" ,请问这是怎么回事
Delbookfrm d = new Delbookfrm ();
}
{
}
加上这个方法
然后把你要执行的代码放这里,或者调用你的方法
public static void main(String[] args){
new Delbookfrm();
}
Delbookfrm d = new Delbookfrm ();
import java.util.*;
import java.awt.*;
import java.io.*;
import java.net.*;
import java.sql.*;
import java.awt.event.*;
import javax.swing.*;class Delbookfrm extends JFrame implements ActionListener
{
JLabel l_bookname;
JTextField t_bookname;
JButton b_delbook,b_back;
JPanel pan1,pan2,pan3;
NetConn sql;
Statement sqll;
Delbookfrm()
{
//界面布局
l_bookname=new JLabel("输入你要删除的书籍的名称:");
t_bookname=new JTextField("",10);
b_delbook=new JButton("删除");
b_back=new JButton("返回");
b_delbook.addActionListener(this);
b_back.addActionListener(this);
pan1=new JPanel();pan2=new JPanel();pan3=new JPanel();
pan1.add(l_bookname);pan2.add(t_bookname);pan3.add(b_delbook);pan3.add(b_back);
setLayout(new GridLayout(3,1));
add(pan1);add(pan2);add(pan3);
setBounds(400,300,300,350);
//建立数据库连接
sql=new NetConn();
}
public void actionPerformed(ActionEvent ed)
{
//单击删除按钮的事件处理程序
if(ed.getSource()==b_delbook)
{
try
{
sqll=sql.connect();
//根据给定图书信息将其从数据库中删除
sqll.executeUpdate("delete from books where bookname="+"'"+t_bookname.getText()+"'");
l_bookname.setText("书籍删除成功");
}
catch(SQLException e6)
{}
}
else if(ed.getSource()==b_back)
{
dispose();
}
}
}
}
运行后,显示
C:\java\Delbookfrm.java:1: 需要为 class、interface 或 enum
public static void main(String[] args){
^
C:\java\Delbookfrm.java:61: 需要为 class、interface 或 enum
}
Process completed.请问这又是怎么回事呢?
前面几楼的方法用了后都是一样的如上面的提示