Reputation: 69

How to left align labels in java layouts?

I am trying to align labels to the left. The layout managers simply do not work intuitively or as expected.

I have scoured the Internet and nothing explains what I need. Or examples I have found simply do not work. For example, I have set all alignment parameters, and nothing changes.

Please help.

Labels do not left align.

" I have tried all types of layout and all alignment settings."

  JPanel p0=new JPanel();
  p0.setLayout(new BoxLayout(p0,BoxLayout.Y_AXIS));
  p0.setBorder(new EmptyBorder(10,10,10,10));
  p0.setAlignmentX(0);

  JPanel p0a=new JPanel();
  p0a.setLayout(new BoxLayout(p0a,BoxLayout.X_AXIS));
  JLabel l=new JLabel("Label 1");
  p0a.add(l);
  p0a.setAlignmentX(0);
  l.setAlignmentX(0);
  l.setHorizontalAlignment(0);

  p0.add(p0a);

  JPanel p0b=new JPanel();
  p0b.setLayout(new BoxLayout(p0b,BoxLayout.Y_AXIS));
  p0b.add(new JLabel("Label 1"));
  p0.add(p0b);

  JPanel p0c=new JPanel();
  p0c.setLayout(new BoxLayout(p0c,BoxLayout.Y_AXIS));
  p0c.add(new JLabel("Label 1"));
  p0.add(p0c);

"create labels"


  JPanel p1=new JPanel();
  p1.setLayout(new BoxLayout(p1,BoxLayout.X_AXIS));
  p1.add(new JLabel("Label 4a"));
  p1.add(new JLabel("Label 4b"));
  p1.add(new JLabel("Label 4c"));
  p1.add(new JLabel("Label 4d"));
  p0.add(p1);

  p0.add(new JLabel("Label 5"));
  p0.add(new JLabel("Label 6"));
  p0.add(new JLabel("Label 7"));

  JDialog jd=new JDialog();
  jd.addWindowListener(new WindowAdapter(){public void windowClosing(WindowEvent _e){jd.setVisible(false);}});
  jd.setLayout(new BoxLayout(jd.getContentPane(),BoxLayout.Y_AXIS));
  Container c=jd.getContentPane();
  jd.setLayout(new BoxLayout(c,BoxLayout.Y_AXIS));
  c.add(p0);
  jd.pack();
  jd.setVisible(true);

" Labels do not align to the left."

Upvotes: 0

Answers (1)

fiveobjects

Reputation: 4269

When X alignment is set to LEFT_ALIGNMENT, all components added to the parent, all will be left-aligned. Same goes for RIGHT_ALIGNMENT. When mixed behavior is different.

To fix your problem minimally just add set X alignment to the panel having multiple labels added horizontally.

JPanel p1=new JPanel();
p1.setLayout(new BoxLayout(p1,BoxLayout.X_AXIS));
p1.add(new JLabel("Label 4a"));
p1.add(new JLabel("Label 4b"));
p1.add(new JLabel("Label 4c"));
p1.add(new JLabel("Label 4d"));
p1.setAlignmentX(Component.LEFT_ALIGNMENT);

Other Options

There are many choices - using simple X alignment consistently and another sophisticated option is using Box.

Set X Alignment of all child components

The first option is to use setAlignmentX(Component.LEFT_ALIGNMENT) on the child components added to the parent.

private static void addAndLeftAlign(JComponent parent, JComponent child) {
    child.setAlignmentX(Component.LEFT_ALIGNMENT);
    parent.add(child);
}

Here is your modified code:

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.*;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Random;

public class LeftAlignLabels57538179 {
    public static void main(String[] args) {
        JPanel p0 = new JPanel();
        //p0.setBackground(Color.ORANGE);
        p0.setLayout(new BoxLayout(p0, BoxLayout.Y_AXIS));
        p0.setBorder(new EmptyBorder(10, 10, 10, 10));
        p0.setAlignmentX(0);

        JPanel p0a = new JPanel();
        p0a.setLayout(new BoxLayout(p0a, BoxLayout.X_AXIS));
        JLabel l = new JLabel("Label 1");
        p0a.add(l);
        //p0a.setAlignmentX(0);
        //l.setAlignmentX(0);
        //l.setHorizontalAlignment(0);

        //p0.add(p0a);
        addAndLeftAlign(p0, p0a);

        JPanel p0b = new JPanel();
        p0b.setLayout(new BoxLayout(p0b, BoxLayout.Y_AXIS));
        p0b.add(new JLabel("Label 1"));
        //p0.add(p0b);
        addAndLeftAlign(p0, p0b);

        JPanel p0c = new JPanel();
        p0c.setLayout(new BoxLayout(p0c, BoxLayout.Y_AXIS));
        p0c.add(new JLabel("Label 1"));
        //p0.add(p0c);
        addAndLeftAlign(p0, p0c);
        //"create labels"


        JPanel p1 = new JPanel();
        p1.setLayout(new BoxLayout(p1, BoxLayout.X_AXIS));
        p1.add(new JLabel("Label 4a"));
        p1.add(new JLabel("Label 4b"));
        p1.add(new JLabel("Label 4c"));
        p1.add(new JLabel("Label 4d"));
        //p0.add(p1);
        addAndLeftAlign(p0, p1);

        addAndLeftAlign(p0, new JLabel("Label 5"));
        addAndLeftAlign(p0, new JLabel("Label 6"));
        addAndLeftAlign(p0, new JLabel("Label 7"));

        JDialog jd = new JDialog();
        jd.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent _e) {
                jd.setVisible(false);
            }
        });
        jd.setLayout(new BoxLayout(jd.getContentPane(), BoxLayout.Y_AXIS));
        Container c = jd.getContentPane();
        jd.setLayout(new BoxLayout(c, BoxLayout.Y_AXIS));
        c.add(p0);
        jd.pack();
        jd.setVisible(true);
    }

    private static void addAndLeftAlign(JComponent parent, JComponent child) {
        child.setAlignmentX(Component.LEFT_ALIGNMENT);
        parent.add(child);
    }
}

Box Option

To left-align another option to use Box a very lightweight component in the following way:

private static void addAndLeftAlign(JComponent parent, JComponent child){
    Box  b = Box.createHorizontalBox();
    b.add(child);
    b.add( Box.createHorizontalGlue() );
    parent.add(b);
}