public void ShowTests()
    {
        tblTests.removeAll();
        String[] column={"Test ID","Patient ID","Doctor ID", "Test Date"};
        int n = ReturnedTests.size();
        if (n <= 0)
        {
            ShowTInfo(new Test());
            String[][] row=new String[1][4];
            tblTests.removeAll();
            DefaultTableModel tmd=new DefaultTableModel(row,column);
            tblTests.setModel(tmd);
            return;
        }
        String[][] ts = new String[n][4];
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
        for(int i=0;i<n;i++)
        {
            Test t = (Test)ReturnedTests.get(i);
            ts[i][0] = PIDtoString(t.TestID);
            ts[i][1] = PIDtoString(t.PatientID);
            ts[i][2] = t.DoctorID;
            ts[i][3] = sdf.format(t.TestDate);
            
        }
        tblTests.removeAll();
        DefaultTableModel tmd=new DefaultTableModel(ts,column);
        tblTests.setModel(tmd);

        ShowTInfo((Test)ReturnedTests.get(0));
    }