cannot select from JList

[Nazerke]

import java.awt.*;
import java.awt.event.MouseEvent;
import java.io.*;
import java.util.logging.*;
import javax.swing.*;

public class NewMain extends JFrame {

boolean action=false;
JButton next;
JList list;
JScrollPane jScrollPane1;
String a[];

public NewMain()
{

jScrollPane1 = new JScrollPane();
next = new JButton();
setLayout(new FlowLayout());

next.setText("next");
next.addMouseListener(new java.awt.event.MouseAdapter() {
public void mouseClicked(java.awt.event.MouseEvent evt) {
try {
buttonMouseClicked(evt);
} catch (IOException ex) {
Logger.getLogger(GUI.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
add(next);

list=new JList();
add(list);
}


private void buttonMouseClicked(MouseEvent evt) throws IOException {
action=true;
}

public void getArray()
{
int i=0;
a=new String[]{"item1","item2","item3","item4"};

do{
list.setListData(a);
if(action==true){
i++;
System.out.println(i+" "+list.getSelectedValue());
action=false;
continue;
} }
while(i<a.length);
}
public static void main(String args[])
{
NewMain a = new NewMain();

a.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
a.setSize(500,500);
a.setVisible(true);
a.getArray();
}
}