Java swing, null pointer

Question

Someone please help me with the null pointer exception so basically my idea was to call back the panel itself and it happened to have null point, why? JPanel contentPane = new AnnualPerformancePanel(mf); mf.setContentPane(contentPane); mf.setVisible(true); this few code that causes the problem.

public class AnnualPerformancePanel extends MasterPanel {
public static int yearCon;




public AnnualPerformancePanel(JFrame mf, int yearContainer) {
super(mf);

JPanel ChartPanel = new JPanel();
ChartPanel.setBounds(15, 133, 960, 415);
add(ChartPanel);

yearCon = yearContainer;


JLabel lblAnnualPerformance = new JLabel("Annual Performance");
    lblAnnualPerformance.setFont(new Font("Verdana", Font.BOLD, 25));
    lblAnnualPerformance.setBounds(362, 71, 304, 32);
    add(lblAnnualPerformance);

    JLabel lblAnnualStatement = new JLabel("Annual Statement");
    lblAnnualStatement.setFont(new Font("Verdana", Font.PLAIN, 15));
    lblAnnualStatement.setBounds(15, 109, 146, 20);
    add(lblAnnualStatement);


    GregorianCalendar calendar = new GregorianCalendar();
    int calendarYear = calendar.getTime().getYear() - 100 +2000;
    int calendarMonth = calendar.getTime().getMonth();
    String[] year = {"2017","2016","2015","2014","2013"};
    JComboBox YearFilter = new JComboBox(year);
    YearFilter.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent arg0) {
    for(int i =5;i>0;i--){

    if(calendarYear == yearContainer){
    System.out.println("===++=====");
    YearFilter.setSelectedItem(yearContainer);
    }
    }
    }
    });


    JFreeChart barChart =       ChartFactory.createBarChart("","Month","Amount",BarChart_AWT.createDataset(yearContainer),PlotOrientation.VERTICAL,true, true, false);  
    ChartPanel chartPanel = new ChartPanel( barChart );        
    chartPanel.setPreferredSize(new java.awt.Dimension( 900 , 400 ) );    
    ChartPanel.add(chartPanel);

    YearFilter.setBounds(162, 109, 82, 20);
    add(YearFilter);
    YearFilter.setSelectedIndex(calendarMonth);




    JLabel lblTotalAmountSpent = new JLabel("Total Amount Spent");
    lblTotalAmountSpent.setFont(new Font("Verdana", Font.PLAIN, 15));
    lblTotalAmountSpent.setBounds(28, 591, 170, 20);
    add(lblTotalAmountSpent);

    JLabel lblExceededCreditUsage = new JLabel("Exceeded Credit Usage");
    lblExceededCreditUsage.setFont(new Font("Verdana", Font.PLAIN, 15));
    lblExceededCreditUsage.setBounds(28, 555, 183, 20);
    add(lblExceededCreditUsage);
    System.out.println("===================");
    JButton btnNewButton = new JButton("Submit");
    btnNewButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent arg0) {
    JPanel contentPane = new AnnualPerformancePanel(mf);
    mf.setContentPane(contentPane);
    mf.setVisible(true);



    }
    });

    btnNewButton.setFont(new Font("Tahoma", Font.PLAIN, 16));
    btnNewButton.setBounds(259, 109, 107, 20);
    add(btnNewButton);




    double totalAmount = 0;
    ArrayList<Transaction> result = TransactionDA.retrieveAllTransaction();
    for(int i =0; i<result.size(); i++){


   if(Integer.parseInt(result.get(i).getTransactionDate().substring(6,8)) ==      calendarYear){
        totalAmount += result.get(i).getTransactionAmount();
        }
    }




   }
   }

Stack trace

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at AnnualPerformancePanel$2.actionPerformed(AnnualPerformancePanel.java:114)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at    java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at   java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at      java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Un known Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)