To add a row of data to a JTable component, you need to add it to its table model. A simple implementation of a table model that supports appending row data is DefaultTableModel. By default, a table uses a DefaultTableModel. 
    DefaultTableModel model = new DefaultTableModel();
    JTable table = new JTable(model);
    
    // Create a couple of columns
    model.addColumn("Col1");
    model.addColumn("Col2");
    
    // Append a row
    model.addRow(new Object[]{"v1", "v2"});
    // there are now 2 rows with 2 columns
    
    // Append a row with fewer values than columns.
    // The left-most fields in the new row are populated
    // with the supplied values (left-to-right) and fields
    // without values are set to null.
    model.addRow(new Object[]{"v1"});
    // there are now 3 rows with 2 columns
    
    // Append a row with more values than columns.
    // The extra values are ignored.
    model.addRow(new Object[]{"v1", "v2", "v3"});
    // there are now 4 rows with 2 columns