Java Swing : JSplitPane split two component equals size at start up

I'm using `JSplitPane` includes two `JScrollPane` at each side. I don't know how to make them at equals size at start up. Here is my main code: ``` contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); contentPane.setLayout(new BorderLayout(0, 0)); setExtendedState(java.awt.Frame.MAXIMIZED_BOTH); inputTextArea = new JTextArea(); outputTextArea = new JTextArea(); // put two TextArea to JScrollPane so text can be scrolled when too long JScrollPane scrollPanelLeft = new JScrollPane(inputTextArea); JScrollPane scrollPanelRight = new JScrollPane(outputTextArea); // put two JScrollPane into SplitPane JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, scrollPanelLeft, scrollPanelRight); splitPane.setOneTouchExpandable(true); splitPane.setDividerLocation(650); // still no effect contentPane.add(splitPane, BorderLayout.CENTER); ``` I have used `splitPane.setDividerLocation(getWidth() / 2);` but still no effect. Please tel me how to fix this. For more detail. Here is my full code: ``` package com.view; import java.awt.BorderLayout; import java.awt.EventQueue; import java.awt.FlowLayout; import java.awt.GridLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.ButtonGroup; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JRadioButton; import javax.swing.JScrollPane; import javax.swing.JSplitPane; import javax.swing.JTextArea; import javax.swing.border.EmptyBorder; //import com.controller.Controller; public class Main extends JFrame { private static final long serialVersionUID = 1L; private JPanel contentPane; public JTextArea inputTextArea; public JTextArea outputTextArea; private JButton inputBtn; private JButton outputBtn; private JButton sortBtn; public JRadioButton firstButton; public JRadioButton secondButton; public JRadioButton thirdButton; JSplitPane splitPane; //Controller controller; /** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { Main frame = new Main(); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the frame. */ public Main() { // controller = new Controller(this); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 450, 300); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); contentPane.setLayout(new BorderLayout(0, 0)); /** * center * include two TextArea for display text */ inputTextArea = new JTextArea(); outputTextArea = new JTextArea(); // put two TextArea to JScrollPane so text can be scrolled when too long JScrollPane scrollPanelLeft = new JScrollPane(inputTextArea); JScrollPane scrollPanelRight = new JScrollPane(outputTextArea); // put two JScrollPane into SplitPane JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, scrollPanelLeft, scrollPanelRight); splitPane.setOneTouchExpandable(true); contentPane.add(splitPane, BorderLayout.CENTER); /** * Top * Include two button : SelectFile and WriteToFile * this layout includes some tricky thing to done work */ // create new input button inputBtn = new JButton("Select File"); // declare action. when user click. will call Controller.readFile() method // (see this method for detail) inputBtn.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { // controller.readFile(); } }); // create new output button outputBtn = new JButton("Write To File"); // declare action. when user click. will call Controller.writeFile() method // (see this method for detail) outputBtn.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { // controller.writeFile(); } }); // put each button into seperate panel JPanel tmpPanel1 = new JPanel(); tmpPanel1.add(inputBtn); JPanel tmpPanel2 = new JPanel(); tmpPanel2.add(outputBtn); // finnally. put those two pane into TopPane // TopPane is GridLayout // by using this. we can sure that both two button always at center of screen like Demo JPanel topPanel = new JPanel(); topPanel.setLayout(new GridLayout(1, 2)); topPanel.add(tmpPanel1); topPanel.add(tmpPanel2); contentPane.add(topPanel, BorderLayout.NORTH); /** * Bottom panel * Include all radionbutton and sortbutton */ // Group the radio buttons. firstButton = new JRadioButton("Last Name"); secondButton = new JRadioButton("Yards"); thirdButton = new JRadioButton("Rating"); // add those button into a group // so . ONLY ONE button at one time can be clicked ButtonGroup group = new ButtonGroup(); group.add(firstButton); group.add(secondButton); group.add(thirdButton); // create sor button sortBtn = new JButton("Sort QB Stats"); // add action for this button : will Call Controller.SortFile() sortBtn.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { // controller.sortFile(); } }); // add all to bottomPanel JPanel bottomPanel = new JPanel(new FlowLayout()); bottomPanel.add(firstButton); bottomPanel.add(secondButton); bottomPanel.add(thirdButton); bottomPanel.add(sortBtn); contentPane.add(bottomPanel, BorderLayout.SOUTH); setContentPane(contentPane); setTitle("2013 College Quarterback Statistics"); setExtendedState(java.awt.Frame.MAXIMIZED_BOTH); setVisible(true); System.out.println("getwidth: " + getWidth()); splitPane.setDividerLocation(getWidth()/2); } } ``` Thanks :)