如何在三角形上填充颜色

做一个Polygon从顶点和填充,而不是通过调用fillPolygon(...):

// A simple triangle.
x[0]=100; x[1]=150; x[2]=50;
y[0]=100; y[1]=150; y[2]=150;
n = 3;

Polygon p = new Polygon(x, y, n);  // This polygon represents a triangle with the above
                                   //   vertices.

g.fillPolygon(p);     // Fills the triangle above.

您需要指定多边形的顶点(在本例中为三角形)并传递给 fillPolygon():

  public void paint(Graphics g) 
  {
    int xpoints[] = {25, 145, 25, 145, 25};
    int ypoints[] = {25, 25, 145, 145, 25};
    int npoints = 5;

    g.fillPolygon(xpoints, ypoints, npoints);
  }