This simple program I have created for you to see how to get all the values in the JList. everythig explained by the comments so that you can understand easily. Also if you want to get selected items in JList you find my gist. If you have any problems, comment below.

Jlist.java

/*

B Liyanage asanka - code snippets for you.
twitter - @bliyanageasanka

*/

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.WindowConstants;

public class Jlist {
 	 //declare components.
	JFrame frame;
	JList<String> list;
	JButton button;
	
 	 //constructor
	public Jlist(){
    		// call the initialize method to create and show GUI
		init();
	}
	
	public void init(){
    		//initialize main frame
		frame = new JFrame("Sample");
    		//frame size
		frame.setSize(300, 300);
    		//layout - to put component in places. Here I used BorderLayout but there is lot.
		frame.setLayout(new  BorderLayout(30, 30));
		
    		//create custom model
		DefaultListModel<String> model = new DefaultListModel<>();
		model.addElement("A");
		model.addElement("B");
		model.addElement("C");
		model.addElement("D");
		model.addElement("E");
		
    		//initialize the JList
		list = new JList<>();
    		//set the custom model that we created before
		list.setModel(model);
    		
		//initialize scroll pane and add list in to it, so if list have lost of element you can scroll through.
		JScrollPane pane = new JScrollPane(list);
		pane.setViewportView(list);
		
    		//initialize the button
		button = new JButton("Get Values");
    
    		//add button click listener
		button.addActionListener(new ActionListener() {
           		 public void actionPerformed(ActionEvent evt) {
                	//call the method to get all values from the list
               		 buttonActionPerformed();
            	}
        	});
		
		
		frame.add(pane, BorderLayout.NORTH);
		frame.add(button, BorderLayout.CENTER);
		frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
		frame.pack();
		frame.setVisible(true);
	}
	
  	//get the all values from this function
	public void buttonActionPerformed(){
		for(int i = 0; i< list.getModel().getSize();i++){
		    System.out.println(list.getModel().getElementAt(i));
		}
	}
	
  	//main method
	public static void main(String[] args) {
    		//instantiate frame window
		new Jlist();
	}
}