Question

我正在尝试创建两个三角形，其中一个是倒置的，另一个是另一个。但是，程序只绘制第一个三角形。我做错了什么？

   public class Triangle extends Applet {


  public void paint( Graphics g ) {

    int[] xPoints = {10, 260, 135};
    int[] yPoints = {250, 250, 10};
    int numPoints = 3;
    // Set the drawing color to black
    g.setColor(Color.black);
    // Draw a filled in triangle
    g.fillPolygon(xPoints, yPoints, numPoints );  

 }


    public void newTriangle( Graphics h ) {

    int[] xPoints2 = {135, 395/2, 145/2};
    int[] yPoints2 = {250, 130, 130};
    int n = 3;

    h.setColor(Color.white);

    h.fillPolygon(xPoints2, yPoints2, n);
  }
}

Answer 1

paint由另一个知道该方法的类调用，因为它在Applet中声明。没有其他类对你的方法有任何了解，它是全新的，所以没有代码可以调用它。如果你想要它被调用，你必须自己做：

public class Triangle extends Applet {

  @Override   //this is good practice to show we are replacing the ancestor's implementation of a method
  public void paint(Graphics g) {
    int[] xPoints = {10, 260, 135};
    int[] yPoints = {250, 250, 10};
    int numPoints = 3;
    // Set the drawing color to black
    g.setColor(Color.black);
    // Draw a filled in triangle
    g.fillPolygon(xPoints, yPoints, numPoints );  

    newTriangle(g); //call your method
 }

 public void newTriangle(Graphics h) {
    int[] xPoints2 = {135, 395/2, 145/2};
    int[] yPoints2 = {250, 130, 130};
    int n = 3;

    h.setColor(Color.white);

    h.fillPolygon(xPoints2, yPoints2, n);
  }
}

试图绘制2个三角形

1 个答案: