How to alignment each JPanel to left or to right into main JPanel

Question

I wanna my app look like this:

I have to try use

jpanel.setAlignmentX(JPanel.LEFT_ALIGNMENT);
jpanel.setAlignmentX(JPanel.RIGHT_ALIGNMENT);

But it's working for first jpanel when I add it into main_JPanel. Show correctly But when I add the JPanel2, JPanel3,... then main_Panel show not correctly, it show this:

This my function create each JPanel

public JPanel makeJpanel(String Mess, String username) {
        int height = 40;
        int width = 200;
        JTextPane textPane = new JTextPane();
        textPane.setEditable(false);
        StyledDocument doc = textPane.getStyledDocument();
        String rs = splitMess(Mess);
        Mess = rs.substring(2).trim();

        Style style = textPane.addStyle("I'm a Style", null);

        StyleConstants.setFontFamily(style, "Arial");
        StyleConstants.setBold(style, true);
        StyleConstants.setFontSize(style, 20);
        StyleConstants.setForeground(style, new Color(19, 51, 55));
        try {
            doc.insertString(doc.getLength(), Mess.trim(), style);
        } catch (BadLocationException e) {
        }
        height = (int) Math.round(textPane.getPreferredSize().getHeight());
        width = (int) Math.round(textPane.getPreferredSize().getWidth());

        //creat avatar
        JLabel ava = null;
        if (username.equals(this.userName)) {
            ava = new JLabel(label_myAvaProfile1.getIcon());
        } else {
            ava = new JLabel(label_avaYourFriends1.getIcon());
        }
        JLabel borderAva = new JLabel(border_label_avaYourFriends.getIcon());
        if (height < 40) {
            ava.setPreferredSize(new Dimension(40, 40));
            borderAva.setPreferredSize(new Dimension(40, 40));
        } else {
            ava.setPreferredSize(new Dimension(40, height));
            borderAva.setPreferredSize(new Dimension(40, height));
        }
        JLayeredPane lpAva = new JLayeredPane();
        lpAva.setLayout(new OverlayLayout(lpAva));
        lpAva.add(borderAva);
        lpAva.add(ava);

        JPanel panelChat = new JPanel();
        panelChat.setLayout(new BoxLayout(panelChat, BoxLayout.LINE_AXIS));
        panelChat.setBackground(Color.WHITE);
        panelChat.setPreferredSize(new Dimension(width + 40, height));
        panelChat.setMinimumSize(new Dimension(width + 40, height));
        panelChat.setMaximumSize(new Dimension(width + 40, height));
        if (username.equals(this.userName)) {
            panelChat.add(textPane);
            panelChat.add(lpAva);
            //NOTICE THIS
            panelChat.setAlignmentX(JPanel.LEFT_ALIGNMENT);
        } else if (username.equals(currentFriendUserName)) {
            panelChat.add(lpAva);
            panelChat.add(textPane);
            //NOTICE THIS
            panelChat.setAlignmentX(JPanel.RIGHT_ALIGNMENT);
        }

        resetPanelListFriends(panelChat);
        return panelChat;
    }

This function I call when i add new Jpanel

public void renderPanelChatLog()
{
    JPanel panelChat = new JPanel();
        panelChat = makeJPanel(mess, username);
        if (panelChat != null) {
            panel_ChatLog.add(panelChat);
            panel_ChatLog.add(Box.createVerticalStrut(20));
        }
        resetPanelListFriends(panel_ChatLog);
}

Sorry My English, I'm just new guy... Plzz help me!

Answer 1

Here is one way:

import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;

public class BoxLayoutAligned
{
    private static void createAndShowGUI()
    {
        JLabel left = new JLabel( "Left Aligned" );
        Box leftBox = Box.createHorizontalBox();
        leftBox.add( left );
        leftBox.add( Box.createHorizontalGlue() );

        JLabel right = new JLabel( "Right Aligned" );
        Box rightBox = Box.createHorizontalBox();
        rightBox.add( Box.createHorizontalGlue() );
        rightBox.add( right );

        Box vertical = Box.createVerticalBox();
        vertical.setBorder( new EmptyBorder(0, 10, 0, 10) );
        vertical.add( leftBox );
        vertical.add( rightBox );

        JFrame frame = new JFrame("BoxLayout Aligned");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(vertical);
        frame.setSize(300, 300);
        frame.setLocationByPlatform( true );
        frame.setVisible( true );
    }

    public static void main(String[] args) throws Exception
    {
        java.awt.EventQueue.invokeLater( () -> createAndShowGUI() );
    }
}

By adding "glue" you allow the other components added to the Box to be aligned to the left or right.