我的 Paint 方法是运行两次，我不知道为什么。我该如何解决这个问题，有人知道为什么会这样吗？

Question

正在使用的 Expo class 基本上只是一个快捷方式，如果有人想要运行我的代码，我可以 link 它。问题是只有用户可以点击的一个方块应该让他们前进，并且随机地，让你前进的方块会改变。所以在第一页上它是[失败][失败][通过]，而下一页，也应该是[失败][失败][通过]，是[通过][通过][通过]。

编辑：世博会 class 实际上对 post 来说太长了，这里有一个 link 可以查看 Link

import java.awt.*;
import java.applet.Applet;


public class BarryViper extends java.applet.Applet
   {
   Rectangle top, mid, bot;
   int numColor;
   int pageNum;

   public void init()
      {
      top = new Rectangle(100,75,150,150);
      mid = new Rectangle(100,275,150,150);
      bot = new Rectangle(100,475,150,150);
      numColor = 0;
      pageNum = 0;
      }

   public void paint(Graphics g)
      {

      switch (pageNum)
         {
         case 0 : page1(g); break;
         case 1 : page2(g); break;
         case 2 : page3(g); break;
         case 3 : page4(g); break;
         // case 4 : page5(g); break;
      //          case 5 : page6(g); break;
      //          case 6 : page7(g); break;
      //          case 7 : page8(g); break;
      //          case 8 : page9(g); break;
      //          case 9 : page10(g); break;
         }
      }


   public boolean mouseDown(Event e, int x, int y)
      {
      if(top.inside(x,y)) 
         numColor = 1;
      else if(mid.inside(x,y)) 
         numColor = 2;
      else if(bot.inside(x,y)) 
         numColor = 3;        
      else
         numColor = 0;
      repaint();
      return true;

      }


   public void page1(Graphics g)
      {

      Expo.setBackground(g,0);
      Expo.setColor(g,Expo.white);
      Expo.fillRectangle(g,100,75,250,225);
      Expo.fillRectangle(g,100,275,250,425);
      Expo.fillRectangle(g,100,475,250,625);
      Expo.setFont(g,"Arial",Font.BOLD,20);
      Expo.drawString(g,"-You Have been Tasked with slaying the dragon that has forsaken these lands.",260,75);
      Expo.drawString(g,"-This quest will be long, difficult, and full of Monty Python refrences.",260,95);
      Expo.drawString(g,"-Do you accept this task?",260,115);
      Expo.setColor(g,Expo.red);
      Expo.setFont(g,"Arial",Font.BOLD,15);
      Expo.drawString(g,"Nah",155,155);
      Expo.drawString(g,"I Prefer",145,350);
      Expo.drawString(g,"Monty Java",130,370);
      Expo.drawString(g,"Sure I could",130,540);
      Expo.drawString(g,"waste some time",115,560);
      switch (numColor)
         {
         case 0 : pageNum=0; break;
         case 1 : pageNum=0; break;
         case 2 : pageNum=0; break;
         case 3 : pageNum=1; break;

         }   

      }

   public void page2(Graphics g)
      {

      Expo.setBackground(g,0);
      Expo.setColor(g,Expo.white);
      Expo.fillRectangle(g,100,75,250,225);
      Expo.fillRectangle(g,100,275,250,425);
      Expo.fillRectangle(g,100,475,250,625);
      Expo.setFont(g,"Arial",Font.BOLD,20);
      Expo.drawString(g,"-Good Choice! You now decide to roam down an old dirt road, when suddenly",260,75);
      Expo.drawString(g,"-You encounter a group of three Goblins blocking your path",260,95);
      Expo.drawString(g,"-What is your reaction?",260,115);
      Expo.setColor(g,Expo.red);
      Expo.setFont(g,"Arial",Font.BOLD,15);
      Expo.drawString(g,"Hide from them ",115,155);
      Expo.drawString(g,"Try talking",130,350);
      Expo.drawString(g,"To them",130,370);
      Expo.drawString(g,"Attack them",130,540);
      Expo.drawString(g,"immediately",130,560);
      switch (numColor)
         {
         case 0 : pageNum=0; break;
         case 1 : pageNum=0; break;
         case 2 : pageNum=0; break;
         case 3 : pageNum=2; break;

         }     


      }

   public void page3(Graphics g)
      {

      Expo.setBackground(g,0);
      Expo.setColor(g,Expo.white);
      Expo.fillRectangle(g,100,75,250,225);
      Expo.fillRectangle(g,100,275,250,425);
      Expo.fillRectangle(g,100,475,250,625);
      Expo.setFont(g,"Arial",Font.BOLD,75);
      Expo.drawString(g,"PAGE 3",200,75);
      switch (numColor)
         {
         case 0 : pageNum=0; break;
         case 1 : pageNum=0; break;
         case 2 : pageNum=0; break;
         case 3 : pageNum=3; break;

         }    

      }

   public void page4(Graphics g)
      {

      Expo.setBackground(g,0);
      Expo.setColor(g,Expo.white);
      Expo.fillRectangle(g,100,75,250,225);
      Expo.fillRectangle(g,100,275,250,425);
      Expo.fillRectangle(g,100,475,250,625);
      Expo.setFont(g,"Arial",Font.BOLD,75);
      Expo.drawString(g,"PAGE 4",200,75);
      switch (numColor)
         {
         case 0 : pageNum=0; break;
         case 1 : pageNum=0; break;
         case 2 : pageNum=0; break;
         case 3 : pageNum=4; break;

         }    


      }







   }

Answer 1

实际上，当系统需要重新绘制 window 时，paint() 会在任何时候被调用。您可以调整大小、移动或隐藏 window。 paint() 每次都会被调用。将另一个 window 拖到你的上面，你会看到调用了多少次 paint() 。

因此，请勿使用任何逻辑绘画。使用 MVC 模式并将您的绘画与逻辑分开。

特别是 - 将颜色保留在模型中并根据鼠标单击进行更改。然后 paint() 应该使用基于颜色的当前值但不决定它是什么颜色。

如果您想查看代码 - 这里是：

import java.awt.*;
import java.applet.Applet;

public class BarryViper extends java.applet.Applet {
    Rectangle top, mid, bot;
    int numColor;
    int pageNum;

    public void init() {
        top = new Rectangle(100, 75, 150, 150);
        mid = new Rectangle(100, 275, 150, 150);
        bot = new Rectangle(100, 475, 150, 150);
        numColor = 0;
        pageNum = 0;
    }

    public void paint(Graphics g) {

        switch (pageNum) {
        case 0:
            page1(g);
            break;
        case 1:
            page2(g);
            break;
        case 2:
            page3(g);
            break;
        case 3:
            page4(g);
            break;
        }
    }

    public boolean mouseDown(Event e, int x, int y) {
        if (top.inside(x, y))
            numColor = 1;
        else if (mid.inside(x, y))
            numColor = 2;
        else if (bot.inside(x, y))
            numColor = 3;
        else
            numColor = 0;

        switch (numColor) {
        case 0:
            pageNum = 0;
            break;
        case 1:
            pageNum = 0;
            break;
        case 2:
            pageNum = 0;
            break;
        case 3:
            pageNum = pageNum;
            break;
        }

        repaint();
        return true;

    }

    public void page1(Graphics g) {

        Expo.setBackground(g, 0);
        Expo.setColor(g, Expo.white);
        Expo.fillRectangle(g, 100, 75, 250, 225);
        Expo.fillRectangle(g, 100, 275, 250, 425);
        Expo.fillRectangle(g, 100, 475, 250, 625);
        Expo.setFont(g, "Arial", Font.BOLD, 20);
        Expo.drawString(
                g,
                "-You Have been Tasked with slaying the dragon that has forsaken these lands.",
                260, 75);
        Expo.drawString(
                g,
                "-This quest will be long, difficult, and full of Monty Python refrences.",
                260, 95);
        Expo.drawString(g, "-Do you accept this task?", 260, 115);
        Expo.setColor(g, Expo.red);
        Expo.setFont(g, "Arial", Font.BOLD, 15);
        Expo.drawString(g, "Nah", 155, 155);
        Expo.drawString(g, "I Prefer", 145, 350);
        Expo.drawString(g, "Monty Java", 130, 370);
        Expo.drawString(g, "Sure I could", 130, 540);
        Expo.drawString(g, "waste some time", 115, 560);
    }

    public void page2(Graphics g) {

        Expo.setBackground(g, 0);
        Expo.setColor(g, Expo.white);
        Expo.fillRectangle(g, 100, 75, 250, 225);
        Expo.fillRectangle(g, 100, 275, 250, 425);
        Expo.fillRectangle(g, 100, 475, 250, 625);
        Expo.setFont(g, "Arial", Font.BOLD, 20);
        Expo.drawString(
                g,
                "-Good Choice! You now decide to roam down an old dirt road, when suddenly",
                260, 75);
        Expo.drawString(g,
                "-You encounter a group of three Goblins blocking your path",
                260, 95);
        Expo.drawString(g, "-What is your reaction?", 260, 115);
        Expo.setColor(g, Expo.red);
        Expo.setFont(g, "Arial", Font.BOLD, 15);
        Expo.drawString(g, "Hide from them ", 115, 155);
        Expo.drawString(g, "Try talking", 130, 350);
        Expo.drawString(g, "To them", 130, 370);
        Expo.drawString(g, "Attack them", 130, 540);
        Expo.drawString(g, "immediately", 130, 560);
    }

    public void page3(Graphics g) {

        Expo.setBackground(g, 0);
        Expo.setColor(g, Expo.white);
        Expo.fillRectangle(g, 100, 75, 250, 225);
        Expo.fillRectangle(g, 100, 275, 250, 425);
        Expo.fillRectangle(g, 100, 475, 250, 625);
        Expo.setFont(g, "Arial", Font.BOLD, 75);
        Expo.drawString(g, "PAGE 3", 200, 75);
    }

    public void page4(Graphics g) {

        Expo.setBackground(g, 0);
        Expo.setColor(g, Expo.white);
        Expo.fillRectangle(g, 100, 75, 250, 225);
        Expo.fillRectangle(g, 100, 275, 250, 425);
        Expo.fillRectangle(g, 100, 475, 250, 625);
        Expo.setFont(g, "Arial", Font.BOLD, 75);
        Expo.drawString(g, "PAGE 4", 200, 75);
    }

}

这就是想法 - 将逻辑移至控制器 - 在您的情况下为 mouselistener。这仅是页码的示例。文本也应该这样做。所有文本都应该在模型中，一般来说，您应该只有一种绘制方法可以从您的模型中绘制文本。所以，这些 pageN() 方法也应该消失了。

我的 Paint 方法是 运行 两次，我不知道为什么。我该如何解决这个问题，有人知道为什么会这样吗？

My Paint method is running twice and I have no idea why. How can I fix this, and does anyone know why this is happening?

java

paint

我的 Paint 方法是运行两次，我不知道为什么。我该如何解决这个问题，有人知道为什么会这样吗？