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Thread: Updating TableModel if changing data on DataBase(MySQL)

  1. #1
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    Default Updating TableModel if changing data on DataBase(MySQL)

    Hi everyone!. I have a problem with the table (JTable). I created a table model:
    import java.util.ArrayList;
     
    import javax.swing.table.AbstractTableModel;
     
    @SuppressWarnings("serial")
    public class MyListTableModel extends AbstractTableModel {
     
    	private ArrayList<String>				columnNames	= new ArrayList<String>();
    	private ArrayList<ArrayList<Object>>	data		= new ArrayList<ArrayList<Object>>();
     
    	public MyListTableModel(ArrayList<ArrayList<Object>> data, ArrayList<String> columnNames) {
    		this.columnNames = columnNames;
    		this.data = data;
    		fireTableDataChanged();
    	}
     
    	@SuppressWarnings({ "unchecked", "rawtypes" })
    	public Class getColumnClass(int c) {
    		return getValueAt(0, c).getClass();
    	}
     
    	public int getColumnCount() {
    		return columnNames.size();
    	}
     
    	public String getColumnName(int col) {
    		return columnNames.get(col);
    	}
     
    	public int getRowCount() {
    		synchronized (data) {
    			return data.size();
    		}
    	}
     
    	public Object getValueAt(int row, int col) {
    		synchronized (data) {
    			return data.get(row).get(col);
    		}
    	}
     
    	public boolean isCellEditable(int row, int col) {
    		return false;
    	}
     
    	public void setValueAt(String obj, int row, int col) {
    		synchronized (data) {
    			data.get(row).set(col, obj);
    			fireTableDataChanged();
    		}
    	}
    }
    and develop JTable from this model:
    	private class CalcTableUI extends JScrollPane {
    		CalcTableUI() throws Exception {
    			calcTbl = new JTable(new MyListTableModel(createArrayListData(SQLQueriesBank.getCalcPosting), createArrayListColumns(SQLQueries.getPostTitle)));
    			setViewportView(calcTbl);
    			revalidate();
    		}
    	}

    public static ArrayList<ArrayList<Object>> createArrayListData(String sqlQuery) throws Exception {
    		Connection conn = getConnectToMySQLDB();
    		ArrayList<ArrayList<Object>> dataArLst = new ArrayList<ArrayList<Object>>();
    		try {
    			PreparedStatement st = conn.prepareStatement(sqlQuery);
    			ResultSet rs = st.executeQuery();
    			ResultSetMetaData md = rs.getMetaData();
    			int columnCount = md.getColumnCount();
    			while (rs.next()) {
    				ArrayList<Object> rowArr = new ArrayList<Object>(columnCount);
    				for (int i = 1; i <= columnCount; i++) {
    					rowArr.add(rs.getString(i));
    				}
    				rowArr.trimToSize();
    				dataArLst.add(rowArr);
    			}
    			dataArLst.trimToSize();
    		} catch (Exception e) {
    			JOptionPane.showMessageDialog(new JDialog(), e);
    		} finally {
    			if (conn != null)
    				conn.close();
    		}
    		return dataArLst;
    	}
    public static ArrayList<String> createArrayListColumns(String sqlQuery) throws Exception {
    		Connection conn = getConnectToMySQLDB();
    		ArrayList<String> columnsArr = new ArrayList<String>();
    		try {
    			PreparedStatement st = conn.prepareStatement(sqlQuery);
    			ResultSet rs = st.executeQuery();
    			while (rs.next()) {
    				columnsArr.add(rs.getString(1));
    			}
    			columnsArr.trimToSize();
    		} catch (Exception e) {
    			JOptionPane.showMessageDialog(new JDialog(), e);
    		} finally {
    			if (conn != null)
    				conn.close();
    		}
    		return columnsArr;
    	}
    but when i changing DB tables its not effect to the my CalcTableUI, when i rerun my app, its shows changing, why. where i wrong and/or what is missing ?


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Updating TableModel if changing data on DataBase(MySQL)

    Are you saying you're updating the data stored in the model but the JTable isn't showing the change?
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  3. #3
    Super Moderator copeg's Avatar
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    Default Re: Updating TableModel if changing data on DataBase(MySQL)

    You shouldn't expect the table to change, as when you load the data into the table you have 2 copies of the data. How does one know to change when the other changes? This problem is a lot harder to solve than one might think, one solution would be to build a notification system (which in its simplest form would require an inner tier to keep track and notify all clients of a datachange, and all changes go through this tier). This is not trivial

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