在Java中使用盒子布局

Question

the following codes created a box layout conviniently but the problem i have is the textfields occupy the entire rows. which is supposed to asume the parameter length in which it was specified.

 public void makeControlpanel(){
    JPanel controlpanel = new JPanel();
     //SET PANEL LAYOUT MANAGERS
    controlpanel.setLayout(new BoxLayout(controlpanel,BoxLayout.PAGE_AXIS));

    controlpanel.setBorder(BorderFactory.createTitledBorder("Create Control file")); 


    filenameC   = new JLabel("Filename");
    filenameBad   = new JLabel("Bad Filename");
    filenameDis = new JLabel("Discard Filename");

    // fields
    fileField = new JTextField(1);
    badfileField = new JTextField(7);
    discardfileField = new JTextField(7);

Answer 1

The layout manager decides the size of the components. You have options to define the bounds of a component to the layout manager using

comp.setMinimumSize(new Dimension(w, h));
comp.setPreferredSize(new Dimension(w, h));
comp.setMaximumSize(new Dimension(w, h));

When you give setPreferredSize layout manager will try to give that size. GridBagLayout is the msot flexible layout and you can prettymuch achieve any layout you need.

The parameter length by defenition only defines the character you can put in the textfield.