Question

所以在我的GUI中，我有一个JFrame，它是一个borderlayout。在北部和西部有一个菜单栏和一些GUI。在CENTER，有一个JLabel。我想让它移动到JPanel的中心（水平和垂直）。我该怎么做？我尝试了盒子布局和网格布局。一个要求是我不能使用gridbag布局。

public class NewClass extends JFrame{
    public NewClass () {
        setVisible(true);
        setSize(500,500);
        setDefaultCloseOperation (EXIT_ON_CLOSE);

//menubar
        JMenuBar bar = new JMenuBar();
        JMenu editMenu = new JMenu("Edit");
        JMenuItem mItem = new JMenuItem("Cut"); // edit->cut
        editMenu.add(mItem);
        mItem = new JMenuItem("Copy"); // edit->copy
        editMenu.add(mItem);
        mItem = new JMenuItem("Paste"); // edit->paste
        editMenu.add(mItem);
        bar.add(editMenu);
        this.setJMenuBar(bar);

//north panel
        JPanel topPanel = new JPanel();
        this.add(topPanel,BorderLayout.NORTH);
        JLabel myLabel = new JLabel ("Label:") ;
        topPanel.add(myLabel);
        JButton mytopButton = new JButton ("Push Me");
        topPanel.add(mytopButton);

//left panel
        JPanel leftPanel = new JPanel();
        leftPanel.setBorder (new TitledBorder("Commands:"));
        leftPanel.setLayout (new GridLayout (10,1));
        this.add(leftPanel,BorderLayout.WEST);
        JButton myLeftButton1 = new JButton ("Button 1");
        leftPanel.add(myLeftButton1);
        JButton myLeftButton2 = new JButton ("Button 2");
        leftPanel.add(myLeftButton2);
        JButton myLeftButton3 = new JButton ("Button3");
        leftPanel.add(myLeftButton3);

//center panel
        JPanel centerPanel = new JPanel();
        this.add(centerPanel,BorderLayout.CENTER);
        JLabel mapLabel = new JLabel("Test_String"); //move this to center of JPanel
        centerPanel.add(mapLabel);
        centerPanel.setBorder (new EtchedBorder(Color.black,Color.black));
        centerPanel.setBackground (Color.white);
    }
}

Answer 1

检查API以查找影响组件alignment的方法。

有些方法会影响布局管理器中组件的对齐以及影响标签本身内文本对齐的其他方法。

Answer 2

首先看看JavaDocs for JLabel

具体而言，JLabel#setHorizontalAlignment和JLabel#setVerticalAlignment

Answer 3

回答。谢谢大家。

    JPanel centerPanel = new JPanel();
    centerPanel.setLayout (new GridLayout ()); //added
    this.add(centerPanel,BorderLayout.CENTER);
    JLabel mapLabel = new JLabel("Test_String");
    mapLabel.setHorizontalAlignment(SwingConstants.CENTER); //added
    mapLabel.setVerticalAlignment(SwingConstants.CENTER); //added
    centerPanel.add(mapLabel);
    centerPanel.setBorder (new EtchedBorder(Color.black,Color.black));
    centerPanel.setBackground (Color.white);

Java：如何将JLabel移动到JPanel的中心？

3 个答案: