Java数据库

Question

使用Java来撷取数据库的记录时，提示“string index out of range:-1”怎么处理？

Answer 1

import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;import javax.swing.*;
import java.sql.*;
public class db2 extends JFrame
{
Connection ConnObj;
Statement SQLStatement;
ResultSet RS;
JPanel ContentPane;
Panel Panel1;
Label L1,L2,L3,L4;
TextField T1,T2,T3,T4;
Button B1,B2,B3,B4;
public db2()
{
ContentPane=(JPanel)this.getContentPane();
ContentPane.setLayout(null);
Panel1=new Panel();
Panel1.setBounds(0,0,290,130);
Panel1.setLayout(null);
Panel1.setEnabled(false);
ContentPane.add(Panel1);
L1=new Label("ISBN:");
L1.setBounds(20,10,50,25);
Panel1.add(L1);
L2=new Label("书名：");
L2.setBounds(20, 40, 50, 25);
Panel1.add(L2);
L3=new Label("作者：");
L3.setBounds(20, 70, 50, 25);
Panel1.add(L3);
L4=new Label("价格：");
L4.setBounds(20, 100, 50, 25);
Panel1.add(L4);
T1=new TextField();
T1.setBounds(70,10,200,25);
Panel1.add(T1);
T2=new TextField();
T2.setBounds(70,40,200,25);
Panel1.add(T2);
T3=new TextField();
T3.setBounds(70,70,200,25);
Panel1.add(T3);
T4=new TextField();
T4.setBounds(70,100,200,25);
Panel1.add(T4);
B1=new Button("第一条");
B1.setBounds(new Rectangle(10,150,65,20) );
B1.addMouseListener(new MouseAdapter()
{
public void mouseClicked(MouseEvent e)
{
B1_mouseClicked(e);
}
}
);
ContentPane.add(B1);
B2=new Button("上一条");
B2.setBounds(80,150,65,20);
B2.addMouseListener(new MouseAdapter()
{
public void mouseClicked(MouseEvent e)
{
B2_mouseClicked(e);
}
}
);
ContentPane.add(B2);
B3=new Button("下一条");
B3.setBounds(150,150,65,20);
B3.addMouseListener(new MouseAdapter()
{
public void mouseClicked(MouseEvent e)
{
B3_mouseClicked(e);
}
}
);
ContentPane.add(B3);
B4=new Button ("最末条");
B4.setBounds(220,150,65,20);
B4.addMouseListener(new MouseAdapter()
{
public void mouseClicked(MouseEvent e)
{
B4_mouseClicked(e);
}
}
);
ContentPane.add(B4);
this.setBounds(200, 100, 310, 210);
this.setTitle("使用select语句");
this.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
this.setVisible(true);
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
ConnObj=DriverManager.getConnection("jdbc:odbc:db2");
SQLStatement=ConnObj.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
RS=SQLStatement.executeQuery("SELECT*FROM BookData1");
if(RS.next())
{
T1.setText(RS.getString("ISBN"));
T2.setText(RS.getString("BookName"));
T3.setText(RS.getString("Author"));
T4.setText(String.valueOf(RS.getInt("Price")));
}
else
JOptionPane.showMessageDialog(this,"myBook数据库内，无任何数据");
}
catch (Exception ecp)
{
JOptionPane.showMessageDialog(this,ecp.getMessage());

}
}
void B1_mouseClicked(MouseEvent e)
{
try
{
RS.first();
T1.setText(RS.getString("ISBN"));
T2.setText(RS.getString("BookName"));
T3.setText(RS.getString("Author"));
T4.setText(String.valueOf(RS.getInt("Price")));
}
catch(SQLException ecp)
{

}
}

void B2_mouseClicked(MouseEvent e)

{
try
{
if(RS.previous())
{
T1.setText(RS.getString("ISBN"));
T2.setText(RS.getString("BookName"));
T3.setText(RS.getString("Author"));
T4.setText(String.valueOf(RS.getInt("Price")));
}
else
{
RS.first();
JOptionPane.showMessageDialog(B2, "已到第一条");

}
}
catch (Exception ecp)
{

}

}
void B3_mouseClicked(MouseEvent e)

{
try
{
if(RS.next())
{
T1.setText(RS.getString("ISBN"));
T2.setText(RS.getString("BookName"));
T3.setText(RS.getString("Author"));
T4.setText(String.valueOf(RS.getInt("Price")));
}
else
{
RS.last();
JOptionPane.showMessageDialog(B3, "已到最末条");

}
}
catch (Exception ecp)
{

}

}
void B4_mouseClicked(MouseEvent e)

{
try
{
RS.last();
T1.setText(RS.getString("ISBN"));
T2.setText(RS.getString("BookName"));
T3.setText(RS.getString("Author"));
T4.setText(String.valueOf(RS.getInt("Price")));
}
catch(SQLException ecp) 
{

}
}

public static void main(String[] args)
{
new db2();
}

}

Answer 2

没有你的数据库。用 h2 建立了一个表，试了一下，没遇到你说的问题。ps.位于第一或末尾 时 通过禁用jbutton 前一个/后一个 而不是弹出对话框