1) Contents of Text Field transfer to Combo Box using Action Event

 source code name: TextComboDemo.java

    import java.awt.*;
   import java.util.*;
    import java.awt.event.*;
 class TextComboDemo extends Frame
{
Font f1=new Font("High Tower Text",Font.BOLD,18);

TextField t1;
Choice ch;
 public TextComboDemo()
{ 
FlowLayout fl=new FlowLayout();
setLayout(fl);     
Label l1=new Label("enter OS Name ");
t1=new TextField(20);
ch=new Choice();
ch.add("windows");
Button b1=new Button("transfer");//create button 
add(l1);add(t1);add(b1); //adding label , textfiled and button on frame 
add(ch);
b1.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent ae)
{
ch.add(t1.getText());
}
});
    } 

    public static void main(String[] args) { 
TextComboDemo f=new TextComboDemo();

f.setSize(400,500); 
 f.setVisible(true); 
    }
}  

output: