java - 为什么我的字符串没有在我的绘画方法中更新？

Question

我正在尝试更改我的网格系统中位置 (0, 1) 处的文本，但由于某种原因，它之前的数字会保留在那里，所以如果我将它从 0 更改为 1，它是0 与 1 重叠。导致此问题的代码有什么问题？

主类:

package Tetris;

import java.awt.Color;
import javax.swing.JFrame;

class Tetris {

    JFrame frame;

    public Tetris() {
        frame = new JFrame("Tetris");
        frame.setSize(500, 500);
        frame.setVisible(true);
        frame.setResizable(false);
        //frame.setLocationRelativeTo(null);
        frame.getContentPane().setBackground(Color.LIGHT_GRAY);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(new Board(frame));
    }

    public static void main(String[] args) {
        new Tetris();
    }
}

游戏类:

package Tetris;

import java.awt.Graphics;
import java.awt.event.*;
import javax.swing.*;

public class Board extends JPanel {

    private static final long serialVersionUID = -5635526290001171288L;

    private int[][] boardLayout;
    private int[] piecePos;

    private float timerCount = 0.0f;

    private String boardLayoutString;

    private Timer timer;

    public Board(JFrame frame) {
        timer = new Timer(10, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                update();
            }
        });
        timer.start();

        boardLayout = new int[8][16];
        piecePos = new int[] { 1, 0 };
        boardLayoutString = "";

        for(int y = 0; y < 16; y++) { // grid system
            for(int x = 0; x < 8; x++) {
                boardLayout[x][y] = 0;
                if(x == 7) {
                    boardLayoutString += boardLayout[x][y] + "\n";
                } else {
                    boardLayoutString += boardLayout[x][y] + " ";
                }
            }
        }

        frame.addKeyListener(new KeyListener() { // maybe put this somewhere else
            public void keyPressed(KeyEvent e) {
                if(e.getKeyCode() == KeyEvent.VK_ESCAPE) {
                    System.exit(0);
                }
                if(e.getKeyCode() == KeyEvent.VK_Q) {
                    boardLayout[1][0] = 2;
                }
            }
            public void keyReleased(KeyEvent e) {
                //
            }
            public void keyTyped(KeyEvent e) {
                //
            }
        });
    }

    private String boardLayoutToString(int[][] boardLayout) {
        boardLayoutString = "";
        for(int y = 0; y < 16; y++) { // grid system
            for(int x = 0; x < 8; x++) {
                if(x == 7) {
                    boardLayoutString += boardLayout[x][y] + "\n";
                } else {
                    boardLayoutString += boardLayout[x][y] + " ";
                }
            }
        }
        return boardLayoutString;
    }

    private void update() {
        timerCount += 0.01f; // every 10ms, add 0.01 - this means 1.0f = 1s

        if(timerCount >= 1.0f) { // do something every 1s           
//          if(piecePos[1] < 8) {
//              boardLayout[piecePos[0]][piecePos[1]] = 1;
//              piecePos[1]++;
//              if(piecePos[1] > 0) {
//                  boardLayout[piecePos[0]][piecePos[1] - 1] = 0;
//              }
//          } else {
//              piecePos = new int[] { 1, 0 };
//          }
            timerCount = 0.0f;
        }
    }

    public void paint(Graphics g) {
        //Graphics2D g2 = (Graphics2D) g;

        for(int i = 0; i < boardLayoutToString(boardLayout).split("\n").length; i++) {
            g.drawString(boardLayoutToString(boardLayout).split("\n")[i], 50, 50 + (i * 15));
        }
        repaint();
    }
}

Answer 1

该来源有一些有问题的特征。

1. 对于 JComponent 中的自定义绘画，请使用 paintComponent(Graphics) 而不是 paint(Graphics)。
2. 立即调用super.paintComponent(Graphics)清除之前的绘制。

其他提示

1. 添加@Override 符号以确保编译时检查。
2. 不要从绘画方法调用 repaint()，而是从由 Swing Timer 控制的 ActionListener 调用它
3. 在添加组件后设置框架可见。