重新验证并重新绘制-Java 6

Question

I am trying to compile my java class files however I am unable to do so due to the java on my school computer being old (java 6) whereas on my own laptop it works (java 7)

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;

public class GUI extends JFrame {

    private Rainfall rainfall;

    /**
     * Creates new form GUI
     */
    public GUI(String fileName) {
        rainfall = new Rainfall(fileName);  //Initialise rainfall data
        this.setTitle("Rainfall Analysis");  //Define the title
        this.setSize(750, 650); //Define the size of the window
        this.setResizable(false); //Disable resizability
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //Definition of the menu
        JMenuBar menuBar = new JMenuBar(); // Initialisation of the first menu bar
        JMenu menuA = new JMenu("Rainfall Information"); // Build first menu
        // A group of JMenuItems
        JMenuItem menuItemA1 = new JMenuItem("Global Information"); // Create a menu item containing "Global Information" as text
        JMenuItem menuItemA2 = new JMenuItem("Month Calendar Based Information");
        JMenuItem menuItemA3 = new JMenuItem("Month Graphical Based Information");
        menuA.add(menuItemA1); 
        menuA.addSeparator(); // We add a seperator to seperate the menu items
        menuA.add(menuItemA2);
        menuA.addSeparator();
        menuA.add(menuItemA3);
        JMenu menuB = new JMenu("Rainfall Analysis"); // Initialisation of the second menu bar
        JMenuItem menuItemB1 = new JMenuItem("Yearly statistics"); // Create a menu item containing "Yearly Statistics" as text
        JMenuItem menuItemB2 = new JMenuItem("Comparison between two months' rainfall"); // Create a menu item 
        menuB.add(menuItemB1); // Add menuItem to the menu(menuB)
        menuB.addSeparator(); // We add a seperator to seperate the menu items
        menuB.add(menuItemB2);

        //Associate events to menu items
        menuItemA1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                setContentPane(new RecordsView(rainfall));   //Make RecordsView as the content panel
                getContentPane().revalidate();
                getContentPane().repaint();
            }
        });

        menuItemA2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                setContentPane(new MonthCalendarView(rainfall));//Make MonthCalendarView as the content panel
                getContentPane().revalidate();
                getContentPane().repaint();
            }
        });

        menuItemA3.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                setContentPane(new MonthGraphicalView(rainfall));//Make MonthGraphicalView as the content panel
                getContentPane().revalidate();
                getContentPane().repaint();
            }
        });

        menuItemB1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                JPanel p = new JPanel();
                p.setSize(750, 650);
                setContentPane(p);
                getContentPane().add(rainfall.getGlobalChartByYears()); //Make Chart that show statistics over years as the content panel
                getContentPane().revalidate();
                getContentPane().repaint();
            }
        });
        menuItemB2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                setContentPane(new ComparisonView(rainfall)); // Set the comparisonView as the content of content pane so that it will be displayed in the GUI
                getContentPane().revalidate();
                getContentPane().repaint();
            }
        });
        menuBar.add(menuA); // Add menuA to menuBar
        menuBar.add(menuB); // Add menuB to menuBar
        //End menu

        this.setJMenuBar(menuBar); // Set the menu bar (menuBar) as the menu bar of the container
        this.setContentPane(new RecordsView(rainfall));

    }

    /**
     * @param args the command line arguments
     */
    public static void main(final String args[]) {

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new GUI(args.length==0?"2RainfallDataLanc.txt":args[0]).setVisible(true);
            }
        });
    }
}

Error received when compiling:

GUI.java:90: cannot find symbol
symbol  : method revalidate()
location: class java.awt.Container
getContentPane().revalidate();
                            ^

java version is: Version 6 Update 45

Whereas I have been working on Version 7 when coding the project.

It seems that version 6 of java does not recognize revalidate.

I have tried to use invalidate, since looking around invalidate is used for java 6.

My question (apologies for not adding it at the start); how would I compile it with java 6?

Thanks

Answer 1

As a workaround you could do

invalidate();
validate();

This approximates to what is occurring in revalidate without RootPane recursion.

Another option is to invoke pack if the window size has not changed.

Although upgrading to Java 7 would be simpler