setAlignmentX(CENTER_ALIGNMENT)不会使JFrame中的boxLayout居中

Question

我想让我的两个JLabel文本保持左对齐，同时把我的boxLayout放在JFrame的中心。

我尝试了setAlignmentX(CENTER_ALIGNMENT)在我的boxlayout面板，但它没有把我的boxlayout在中心。

import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class GuiTest extends JFrame {
    private static final long serialVersionUID = 1L;
    private JLabel jLabelOne = new JLabel();    
    private JLabel jLabelTwo = new JLabel();
    private JPanel panel = new JPanel();
    private BoxLayout boxLayout = new BoxLayout(panel,BoxLayout.Y_AXIS);
    public GuiTest() {
        jLabelOne.setAlignmentX(LEFT_ALIGNMENT);
        jLabelTwo.setAlignmentX(LEFT_ALIGNMENT);
        jLabelOne.setText("This is text one");
        jLabelTwo.setText("This is text two");
        panel.setLayout(boxLayout);
        panel.add(jLabelOne);
        panel.add(jLabelTwo);
        panel.setAlignmentX(CENTER_ALIGNMENT);
        add(panel);
        pack();
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        setSize(1024,768);
        setLocationRelativeTo(null);   
        setVisible(true);
    }
    public static void main(String args[]) {
        new GuiTest();
    }
}

Answer 1

我相信这不会有任何结果:

panel.setAlignmentX(CENTER_ALIGNMENT);

因为你将面板添加到JFrame的contentPane(一个使用BorderLayout的容器)，并且实际上是以默认方式添加它，即BorderLayout. center。

考虑给contentPane一个GridBagLayout，并以默认方式添加面板JPanel，它应该居中。只有当它的首选大小小于JFrame的contentPane时，才会看到。

Answer 2

import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class GuiTest extends JFrame {
    private static final long serialVersionUID = 1L;
    private JLabel jLabelOne = new JLabel();    
    private JLabel jLabelTwo = new JLabel();
    private JPanel panel = new JPanel();
    private BoxLayout boxLayout = new BoxLayout(panel,BoxLayout.Y_AXIS);
    public GuiTest() {
        panel.setLayout(boxLayout);
        jLabelOne.setAlignmentX(CENTER_ALIGNMENT);
        jLabelTwo.setAlignmentX(CENTER_ALIGNMENT);
        jLabelOne.setText("This is text one");
        jLabelTwo.setText("This is text two");
        panel.add(jLabelOne);
        panel.add(jLabelTwo);
        panel.setAlignmentX(CENTER_ALIGNMENT);
        add(panel);
        setSize(1024,768);
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);      
        setLocationRelativeTo(null);   
        setVisible(true);
    }
    public static void main(String args[]) {
        new GuiTest();
    }
}

这应该能得到你想要的。