java - 如何让JComboBox出现在JFrame中？

Question

我有一个 JComboBox，它曾经出现在 JFrame 中，但现在它不出现了...不知道为什么，但我认为它可能与 JPanel 和/或容器有关。我希望有一个 JComboBox，里面有不同的服装类型。 JFrame 出现时没有 JComboBox，这很奇怪。这是我的代码:

 public void init() {
    JComboBox dropDown = new JComboBox(description);
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     Container cont = frame.getContentPane();
        cont.setLayout(new FlowLayout());
        cont.add(t);
        cont.add(c);

    final JPanel pan = new JPanel();
    for (int i=0; i<6; i++){
     c.addItem(description[count++]);
      t.setEditable(false);
    }//end of for
      c.addActionListener(new ActionListener(){  
        public void actionPerformed(ActionEvent evt) {
          if (count < description.length){
            c.addItem(description[count++]);
          }//end of if
            selected = " "+((JComboBox) evt.getSource()).getSelectedItem();
}//end of method
};//end of listener
}//end of method

Answer 1

首先你应用了“;”在你的循环之后。这是一个很大的错误。我已阅读您的代码并做了一些更改。看看这个。此代码在屏幕上显示 JComboBox。

---

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class ans
{
JFrame frame=new JFrame();
String description[]={
"Hello","Bye","Java","Python","Fortran","Pascal"
};
int count=0;


JComboBox c=new JComboBox();
public void init() {
    final JPanel pan = new JPanel();
pan.setLayout(new FlowLayout());
    for (int i = 0; i < 6; i++)
        c.addItem(description[count++]);
        c.setEditable(false);
        c.addActionListener(new ActionListener(){  
            public void actionPerformed(ActionEvent evt) {
                //Do Something
                }//end of if

    // ... ? ...
}});
    frame.setContentPane(c);
    frame.setVisible(true);
    frame.pack();
}
public static void main(String arg[])
{
ans a=new ans();
a.init();
}
}