Java Swing中的垂直对齐

Question

How can I make buttons like this?

        JPanel jp = new JPanel();
        JPanel jpB1 = new JPanel();
        JPanel jpB2 = new JPanel();
        JPanel jpB3 = new JPanel();
        JButton jb1 = new JButton("button1");
        JButton jb2 = new JButton("button2");
        JButton jb3 = new JButton("button3");
            ...
        JLabel jl = new JLabel("label");
        ...
        jp.setLayout(new BorderLayout());
        ...
        jpB1.add(jb1);
        jpB2.add(jb2);
        jpB3.add(jb3);
        ...
        jp.add(jpB1, BorderLayout.NORTH);
        jp.add(jpB2, BorderLayout.CENTER);
        jp.add(jpB3, BorderLayout.SOUTH);
            ...

I tried this code on creating 3 panels and add them to the main panel. It shows two buttons on north and one button on south! Can someone help me?

Answer 1

Note, the default layout of JPanel is FlowLayout ; a GridBagLayout with default constraints is centered in the frame's BorderLayout.CENTER . Also, pack() the enclosing Window and display it last. Using Initial Threads left as an exercise.

Addendum: A useful trick for solving layout problems is setting the background color of an enclosing container to a contrasting color, for example

jpB2.setBackground(Color.blue);

import java.awt.BorderLayout;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Bouton2 {

    public static void main(String[] args) {

        final int LARGEUR = 400;
        final int HAUTEUR = 300;

        JFrame jf = new JFrame();
        JPanel jp = new JPanel();
        JPanel jpB1 = new JPanel();
        JPanel jpB2 = new JPanel(new GridBagLayout());
        JPanel jpB3 = new JPanel();
        JButton jb1 = new JButton("Cliquez ici");
        JButton jb2 = new JButton("Je compte");
        JButton jb3 = new JButton("J'agrandis");

        JLabel jl = new JLabel("0 clic");

        jp.setLayout(new BorderLayout());

        jpB1.add(jb1);
        jpB2.add(jb2);
        jpB3.add(jb3);

        jp.add(jpB1, BorderLayout.NORTH);
        jp.add(jpB2, BorderLayout.CENTER);
        jp.add(jpB3, BorderLayout.SOUTH);

        jf.setTitle("Fenêtre Bouton2");
        jf.setContentPane(jp);
        jf.pack();
        jf.setSize(LARGEUR, HAUTEUR);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.setLocationRelativeTo(null);
        jf.setVisible(true);

    }
}