Vector
public class test extends JFrame implements ActionListener{
Vector vc=new Vector();
vc.add("dddd");JComboBox jcb=new JComboBox(vc);
JButton jb=new JButton();


test(){
jcb.setEditable(true);
setLayout(new FlowLayout());
add(jcb);add(jb);
setTitle("提示框");
setSize(300,300);
setResizable(false);
jb.addActionListener(this);
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setVisible(true);
}
public void actionPerformed(ActionEvent e) {
if(e.getSource()==jb) System.out.print(jcb.getSelectedItem());
}
public static void main(String[] args) {
// TODO Auto-generated method stub
test t1=new test();

}

}
有颜色的地方有问题

[解决办法]
根据提示：Exception in thread "main" java.lang.Error: Unresolved compilation problem:

原因：JVM是通过main运行，不能在public class里先调用vector add
类似问题：不能在main前，调用其他类的method


解决办法：把Vector<String> vc1=new Vector<String>();
vc1.add("aaa");
JComboBox jcb=new JComboBox(vc1);
放进构造器constructor test(){里