actionPerformed

Question

就是这句错。。大家帮下忙吧，万分感谢！！！！！！
我是要把我选项的当前项显示在textArea中，不知道该怎么写
错误提示：F:\study\Java程序设计\上机作业\第三次\Three.java:37: append(java.lang.String) in javax.swing.JTextArea cannot be applied to (java.lang.Object)
jta.append(jcb.getSelectedItem());
                   ^
1 errorTool completed with exit code 1
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class Three implements ActionListener
{
JFrame f;
JComboBox jcb;
JTextArea jta;
JPanel p1,p2;
public static void main(String args[])
{
Three three= new Three();
three.go();
}
public void go()
{
f=new JFrame("Select Demo");
f.setSize(200,300);
f.setVisible(true);
p1=new JPanel();
p2=new JPanel();
String[] itemList={"Mouse Entered","Mouse Pressed","Mouse Released","Mouse Clicked","Mouse Exited"};
jcb=new JComboBox(itemList);
jcb.setSelectedIndex(2);
jta=new JTextArea(100,300);
p1.add(jcb);
p2.add(jta);
f.getContentPane().add(p1,BorderLayout.WEST);
f.getContentPane().add(p2,BorderLayout.EAST);
jcb.addActionListener(this);
jcb.setEditable(false);
}
public void actionPerformed(ActionEvent e)
{
jta.append("\n");
jta.append(jcb.getSelectedItem());
}
}

Answer 1

jcb.getSelectedItem().toString().应该只能append string, object不行.

Answer 2

类型不匹配当然不不行import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
public class Three implements ActionListener
{
    JFrame f;
    JComboBox jcb;
    JTextArea jta;
    JPanel p1,p2;
    public static void main(String args[])
    {
        Three three= new Three();
        
        three.go();
    }
    public void go()
    {
        f=new JFrame("Select Demo");
        f.setSize(200,300);
        
        p1=new JPanel();
        p2=new JPanel();
        String[] itemList={"Mouse Entered","Mouse Pressed","Mouse Released","Mouse Clicked","Mouse Exited"};
        jcb=new JComboBox(itemList);
        jcb.setSelectedIndex(2);
        jta=new JTextArea(10,30);
        p1.add(jcb);
        p2.add(jta);
        f.getContentPane().add(p1,java.awt.BorderLayout.WEST);
        f.getContentPane().add(p2,java.awt.BorderLayout.CENTER);
        jcb.addActionListener(this);
        jcb.setEditable(true);
        f.setVisible(true);
    }
    public void actionPerformed(ActionEvent e)
    {
    
        jta.append("\n");
        jta.append(jcb.getSelectedItem().toString());
        System.out.println(jta.getText());
    }
}

Answer 3

把这一句改成
jta.append((String)jcb.getSelectedItem()); 
OK