将组件动态添加到JPanel中以更改组件大小

Question

1. I am trying to add combo box to the JPanel dynamically but the combo box occupying entire panel.According to the combo box count the size of the combo boxes are changing but I want fixed size of the combo box and I need to create the combo boxes one by one means below of another combo /in a new line.

2. How to set the location of the components in a panel.

    JComboBox startDate = new JComboBox(); startDate.setPreferredSize(new Dimension(80,25)); jPanelStartDate.add(startDate); jPanelStartDate.setLayout(new GridLayout(0, 3, 10, 10)); jPanelStartDate.revalidate(); 

Answer 1

Ok, you have more than one option. You can use a BoxLayout with a Y_Axis and a rigid area or you can use the more advanced, complex and dynamic GridBagLayout . The following is an example with a BoxLayout and rigid areas.

 JFrame frame = new JFrame("Test");
 JPanel panel = new JPanel();

 BoxLayout boxLayout = new BoxLayout(panel, BoxLayout.Y_AXIS);
 panel.setLayout(boxLayout);

 for(int index = 0; index < 5; ++index){

      JComboBox<String> box = new JComboBox<>(new String[]{"a", "b", "c"});

      box.setMaximumSize(new Dimension(50, 50));
      box.setMinimumSize(new Dimension(50, 50));

      panel.add(box);

      panel.add(Box.createRigidArea(new Dimension(10, 10)));
 }

 frame.setContentPane(panel);
 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 frame.setSize(new Dimension(300, 300));
 frame.setVisible(true);

You can change the dimensions, specially of the rigid area to adjust the spaces and the sizes of the components according to your needs.