Any component added to the GridLayout will be resized to the same size as the largest component added. If you want a component to remain at its preferred size, then wrap that component in a JPanel and then the panel will be resized:
JPanel displayPanel = new JPanel(new GridLayout(4, 2));
JTextField titleText = new JTextField("title");
JPanel wrapper = new JPanel( new FlowLayout(0, 0, FlowLayout.LEADING) );
wrapper.add( titleText );
displayPanel.add(wrapper);
//displayPanel.add(titleText);