Re: Memory Leak in swing

  To: comp.lang.java.gui
I stripped-down my code, this also gathers surviving objects.
Application containing this code could not live long. (A thread wait of
1 sec. also does not help.) sorry for the long posting, but it is
really despairing!

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
RAND()";

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

    protected class RefreshTask extends TimerTask {
        @Override
        public void run() {
            random();
        }
    }
    public void go(){
        Timer updateTimer = new Timer("Refresh Task");
        updateTimer.schedule(new
RefreshTask(),0,2000);//instance,delay,interval
    }
    private Image LoadImageFromDB(String personnr){
        Image img = null;
        String filename = personnr + ".jpg";
        Connection con =
DbInterface.getinstance().getEtrainerDBConnection();
        Statement stmt;
        ResultSet rs;
        try {
            stmt = con.createStatement();
            String query =
Resources.getInstance().getDbProperties().getProperty("selectPersonImage");
            query = String.format(query, filename);
            rs=stmt.executeQuery(query);
            if(rs.next()){
                int len=rs.getInt(2);
                byte [] b=new byte[len];
                InputStream in = rs.getBinaryStream(3);
                try {
                    in.read(b);
                    in.close();
                    img=Toolkit.getDefaultToolkit().createImage(b);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            rs.close();
            stmt.close();

        } catch (SQLException e) {
            e.printStackTrace();
        }
        return img;
    }
    public void random(){
        java.sql.Connection con =
DbInterface.getinstance().getSybaseDBConnection();
        try {
            if(con!=null && !con.isClosed()){
                java.sql.Statement stmt=null;
                try {
                    stmt = con.createStatement();
                    java.sql.ResultSet rs =
stmt.executeQuery(randomquery);
                    while(rs.next()){
                        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;
                        }
                        personList.add(person);
                        System.out.println("Container size: " +
personList.size());
                        counter++;
                    }
                    if(counter%20 == 0){
                        personList.clear();
                        System.gc();//no need, but I force for this
example
                        System.out.println("Container cleared, size: "
+ personList.size());
                    }
                    rs.close();
                    stmt.close();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
    }
    public static void main(String[] args) {
        LeakCheck leakCheck = new LeakCheck();
        leakCheck.go();
    }
}

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