Question

程序运行时，按钮被绘制为10X10。我通过“修改菜单”更改了按钮20X20。但是，该按钮不可见。

将鼠标移到按钮上时出现。不要重画。重新验证也不一样。

package com.test; 

import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

public class MenuTest extends JFrame {

    private Dimension dimen, dimen1;
    private int xpos, ypos;
    private JButton[][] btn = null;
    private JPanel p;
    private GridLayout grid;
    private CardLayout card;
    private int rownum;
    private int colnum;
    private int mineLevel;

    public MenuTest() {
        super("GAME");

        p = new JPanel();
        grid = new GridLayout();
        card = new CardLayout();

        createMenu();
        starting();
    }

    private void createMenu() {
        JMenuBar bar = new JMenuBar();
        setJMenuBar(bar);

        JMenu filemenu = new JMenu("파일(F)");
        filemenu.setMnemonic('F');

        JMenuItem startmenu = new JMenuItem("게임 시작(S)");
        startmenu.setMnemonic('S');
        startmenu.setActionCommand("START");
        startmenu.addActionListener(new MenuActionListener());
        filemenu.add(startmenu);

        JMenuItem minecntmenu = new JMenuItem("변경(M)");
        minecntmenu.setMnemonic('M');
        minecntmenu.setActionCommand("MODIFY");
        minecntmenu.addActionListener(new MenuActionListener());
        filemenu.add(minecntmenu);

        JMenuItem close = new JMenuItem("닫기(C)");
        close.setMnemonic('C');
        filemenu.add(close);
        bar.add(filemenu); //JMenuBar에 JMenu 부착 

        //도움말 메뉴 만들기-------------------------------- 
        JMenu helpmenu = new JMenu("도움말(D)");
        helpmenu.setMnemonic('D'); //단축키를 Alf + D 로 설정 

        JMenuItem help = new JMenuItem("Help(H)");
        help.setMnemonic('H');
        helpmenu.add(help);
        bar.add(helpmenu);
    }

    private class MenuActionListener implements ActionListener {

        public void actionPerformed(ActionEvent e) {
            if (e.getActionCommand().equals("START")) {
                JOptionPane.showMessageDialog(null, "게임시작", "게임", JOptionPane.YES_NO_OPTION);
            } else if (e.getActionCommand().equals("MODIFY")) {
                modify();
                JOptionPane.showMessageDialog(null, "변경", "게임", JOptionPane.YES_NO_OPTION);
            }
        }
    }

    private void modify() {
        btn = null;

        setRowColnum(20, 20);
        MapInit(20);
        LayoutSet(400, 500);
    }

    private void starting() {
        setRowColnum(10, 10);
        MapInit(10);
        LayoutSet(200, 250);
    }

    private void setRowColnum(int rownum, int colnum) {
        this.rownum = rownum;
        this.colnum = colnum;
    }

    public static void main(String[] args) {
// TODO Auto-generated method stub 
        MenuTest mt = new MenuTest();
    }

    public void LayoutSet(int w, int h) {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        this.setSize(w, h);

        dimen = Toolkit.getDefaultToolkit().getScreenSize();
        dimen1 = this.getSize();
        xpos = (int) (dimen.getWidth() / 2 - dimen1.getWidth() / 2);
        ypos = (int) (dimen.getHeight() / 2 - dimen1.getHeight() / 2);
        this.setLocation(xpos, ypos);

        this.setVisible(true);
        this.setResizable(false);
    }

    public void MapInit(int minecnt) {
        p.removeAll();
        setBtn(rownum, colnum);

        card = new CardLayout(5, 5);
        this.setLayout(card);
        grid = new GridLayout(rownum, colnum, 0, 0);

        p = new JPanel(grid);

        int action_num = 0;
        for (int i = 0; i < btn.length; i++) {
            for (int j = 0; j < btn[i].length; j++) {
                action_num = (i * 10 + j);
                btn[i][j] = new JButton();
                p.add(btn[i][j]);
            }
        }

        this.repaint();

        this.add("View", p);
    }

    private void setBtn(int row, int col) {
        btn = new JButton[row][col];
    }
}

Answer 1

在可见GUI中添加/删除组件时，基本代码为：

panel.remove(...);
panel.add(...);
...
panel.revalidate();
panel.reapint();

删除/添加所有组件后，您需要执行revalidate()，以便调用布局管理器，并为所有组件指定大小和位置。然后repaint()确保组件被绘制。

不要重新绘制或重新验证

1 个答案: