Memory Leak in a multi threaded java application (ImageIcon)

"cakmak" <>
10 Jan 2007 02:37:12 -0800
When I profile my swing application with netbeans 5.5 , I notice that
after each periodically tidy up my image container (add,remove
IconImage objects to a hashmap or arraylist), there gather by and by
surviving objects. This leads to run out of memory after a while. Is
there any other way to avoid this effect? Any ideas about "The JVM is
notorious for caching images." I stripped-down my code, this also
gathers surviving objects. An application containing this code could
not live long.

public class LeakCheck {
    private int counter=0;
    private final String randomquery = "SELECT TOP 4 T00801PersonNr AS
PersonNr,T00801PersonID AS PersonID, T00801Nachname AS
Nachname,T00801Vorname AS Vorname FROM DBA.T00801Person ORDER BY

    private class Person extends Object {
        private javax.swing.ImageIcon icon;
        private String number;
        protected void finalize() throws Throwable {
                icon = null;
    private ArrayList<Person> personList = new ArrayList<Person>();

    protected class RefreshTask extends TimerTask {
        public void run() {
    public void go(){
        Timer updateTimer = new Timer("Refresh Task");
        updateTimer.schedule(new RefreshTask(),0,2000);
    private Image LoadImageFromDB(String personnr){
        Image img = null;
        String filename = personnr + ".jpg";
        Connection con = getEtrainerDBConnection();
        Statement stmt;
        ResultSet rs;
        try {
            stmt = con.createStatement();
            String query = Resources.getProperty("selectPersonImage");
            query = String.format(query, filename);
                int len=rs.getInt(2);
                byte [] b=new byte[len];
                InputStream in = rs.getBinaryStream(3);
                try {
                } catch (IOException e) {

        } catch (SQLException e) {
        return img;
    public void random(){
        java.sql.Connection con = getSybaseDBConnection();
        try {
            if(con!=null && !con.isClosed()){
                java.sql.Statement stmt=null;
                try {
                    stmt = con.createStatement();
                    java.sql.ResultSet rs =
                        Person person = new Person();
                        person.number = rs.getString("PersonNr");
                        Image img = LoadImageFromDB(person.number);
                        if(img !=null){
                            ImageIcon ico = new ImageIcon(img);
                            person.icon = ico;
                        System.out.println("Container size: " +
                    if(counter%20 == 0){
                        System.gc();//no need, but I force
                        System.out.println("size: " +
                } catch (SQLException ex) {
        } catch (SQLException ex) {
    public static void main(String[] args) {
        LeakCheck leakCheck = new LeakCheck();

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