box.java:31: invalid method declaration; return type required
addWindowListener(new WindowAdapter(){
^
box.java:31: illegal start of type
addWindowListener(new WindowAdapter(){
^
box.java:33: <identifier> expected
});
^
3 errors
-_-b 是3个错
addWindowListener(new WindowAdapter(){
^
box.java:31: illegal start of type
addWindowListener(new WindowAdapter(){
^
box.java:33: <identifier> expected
});
^
3 errors
-_-b 是3个错
import java.awt.event.*;
class box extends Frame
implements ItemListener
{
Checkbox b1,b2,b3,b4;
TextField tf;
box(String t)
{
super(t);
setLayout(new FlowLayout());
b1=new Checkbox("A",false);
b2=new Checkbox("B",false);
b3=new Checkbox("C",false);
b4=new Checkbox("D",false);
add(b1); add(b2); add(b3); add(b4);
b1.addItemListener(this);
b2.addItemListener(this);
b3.addItemListener(this);
b4.addItemListener(this);
tf=new TextField(20);
add(tf);
setSize(40,100);
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){ System.exit(0);}
});
}
public void itemStateChanged(ItemEvent event)
{
tf.setText("Checkbox "+event.getItem().toString());
}
public static void main(String args[])
{
box m=new box("box");
m.show();
}
}不知道这个是哪里来的?
event.getItemSelectable().getLabel());
看看吧:import java.sql.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import javax.swing.event.*;public class VLookup extends JApplet
{
String dbUrl = "jdbc:odbc:people";
String user = "";
String password = "";
Statement s;
JTextField searchFor = new JTextField(20);
JLabel completion = new JLabel(" ");
JTextArea results = new JTextArea(40, 20); public void init()
{
searchFor.getDocument().addDocumentListener(new SearchL());
JPanel p = new JPanel();
p.add(new Label("Last name to search for:"));
p.add(searchFor);
p.add(completion);
Container cp = getContentPane();
cp.add(p, BorderLayout.NORTH);
cp.add(results, BorderLayout.CENTER);
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection c = DriverManager.getConnection(dbUrl, user, password);
s = c.createStatement();
}
catch (Exception e)
{
results.setText(e.toString());
}
} class SearchL implements DocumentListener
{
public void changedUpdate(DocumentEvent e) {}
public void insertUpdate(DocumentEvent e)
{
textValueChanged();
}
public void removeUpdate(DocumentEvent e)
{
textValueChanged();
}
} public void textValueChanged() {
ResultSet r;
if (searchFor.getText().length() == 0)
{
completion.setText("");
results.setText("");
return;
}
try
{
r = s.executeQuery(
"SELECT LAST FROM people.csv people " +
"WHERE (LAST LIKE '" +
searchFor.getText() +
"%') ORDER BY LAST");
if (r.next())
completion.setText(r.getString("last"));
r = s.executeQuery(
"SELECT FIRST, LAST, EMAIL " +
"FROM people.csv people " +
"WHERE (LAST = '" +
completion.getText() +
"') AND (EMAIL Is Not Null) " +
"ORDER BY FIRST");
}
catch (Exception e)
{
results.setText(
searchFor.getText() + "\n");
results.append(e.toString());
return;
}
results.setText("");
try
{
while (r.next())
{
results.append(
r.getString("last") + ", " +
r.getString("first") + ": " +
r.getString("email") + "\n");
}
}
catch (Exception e)
{
results.setText(e.toString());
}
} public static void main(String args[])
{
VLookup l = new VLookup();
JFrame f = new JFrame("Sample JDBC query");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(500, 200);
f.getContentPane().add(l);
l.init();
l.start();
f.setVisible(true);
}
}
我编译后提示的错误是:
C:\Java源代码\第二章\实例17\VLookup.java:39: error while writing VLookup.SearchL: C:\Java源代码\第二章\实例17\VLookup$SearchL.class (拒绝访问。)
class SearchL implements DocumentListener
^
1 errorProcess completed.这是什么错啊?
addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){ System.exit(0);}
});
不过修改后,编译还有一个错误,把的itemStateChanged语句改成这样就可以了
public void itemStateChanged(ItemEvent event)
{
tf.setText("Checkbox "+event.getItemSelectable());
}
C:\Java源代码\第二章\实例17\VLookup$SearchL.class
改一下
{
tf.setText("Checkbox "+event.getItemSelectable());//我想在这里得到被选择的多选框的标签,怎么做? 为什么用getLabel() 不行?
}
这个不是么?event.getItemSelectable()里面就没有getLabel这个方法.