添加JComponent时，java图形中的paint函数是否被多次调用? [英] Is the paint function in java graphics called multiple times when I add a JComponent?

问题描述

我正在制作一个国际象棋游戏，其中每个图块(类)都有一个 X 和 Y 位置，棋盘由二维图块阵列表示.我有一个名为 board 的类，它扩展了 JComponent，我的主函数将板添加到 JFrame.根据我所阅读的内容，paint 函数被隐式调用(不确定).问题是，当我尝试打印瓷砖的 x 和 y 位置(被迭代)时，它会打印所有 x 和 y 位置三遍，这让我相信油漆被调用了不止一次.

I am making a chess game in which each tile(class) holds an X and Y position and the board is represented by a two dimensional array of tiles. I have a class called board which extends JComponent and my main function adds the board to a JFrame. Based on what I have read, the paint function is called implicitly(not sure). The problem is that when i tried printing the x and y position of the tiles(being iterated over) it prints all of the x and y positions three times, which led me to believe that paint is being called more than once.

板类:

class Board extends JComponent{
    Tile[][] board1;
    Board(Pieces p,boolean containPiece){   
        //initialize board
        board1 = board; // set attribute

    }
      public void paint(Graphics g){
          for(int i = 0; i < board1.length; i++){
              for(int j = 0; j < board1.length; j++){
                  g.fillRect(board1[j][i].xPosition+130, board1[j][i].yPosition+20,board1[j][i].tileWidth,board1[j][i].tileHeight);
                  System.out.println(j+ " "+ " " + i );
                  if((j+i)%2 == 0){
                      g.setColor(Color.BLACK);
                  }
                  else{
                      g.setColor(Color.WHITE);
                  }

              }
            }
          }
      }

主类:

 public static void main(String[] args) {
        JFrame frame = new JFrame();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setBounds(350,10,700, 600);
            Knight k = new Knight("Knight","K","white",4,5,3);
            frame.getContentPane().add(new Board(k,true));
            frame.setVisible(true);

        }

输出如下(与代码格式不同但内容相同)但重复了两次:

the output is the following(not in same format as code but same content) but repeated twice more:

0 0, 1 0, 2 0, 3 0, 4 0, 5 0, 6 0, 7 0,
0 1 ,1 1 ,2 1 ,3 1 ,4 1 ,5 1 ,6 1 ,7 1,
0 2 ,1 2 ,2 2 ,3 2 ,4 2 ,5 2 ,6 2 ,7 2 ,
0 3 ,1 3 ,2 3 ,3 3 ,4 3 ,5 3 ,6 3 ,7 3 ,
0 4 ,1 4 ,2 4 ,3 4 ,4 4 ,5 4 ,6 4 ,7 4,
0 5 ,1 5 ,2 5 ,3 5 ,4 5 ,5 5 ,6 5 ,7 5 ,
0 6 ,1 6 ,2 6 ,3 6 ,4 6 ,5 6 ,6 6 ,7 6 ,
0 7 ,1 7 ,2 7 ,3 7 ,4 7 ,5 7 ,6 7 ,7 7 

推荐答案

来自AWT 和 Swing 网站中的 Oracle 绘画

在系统触发的绘制操作中，系统请求组件渲染其内容，通常是出于以下原因之一:

In a system-triggered painting operation, the system requests a component to render its contents, usually for one of the following reasons:

• 组件首先在屏幕上可见.
• 组件已调整大小.
• 组件有损坏需要修复.(例如，之前遮挡组件的东西已经移动，并且组件之前被遮挡的部分已经暴露).

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