How do I plot 2 points in a graph in a GUI?

问题:

I am trying to make a GUI that will plot 2 points in a line graph and draw a line segment from those two points.

I cannot find any examples in any of my Java textbooks, and almost every example that I try to search for is too complex to understand in the short amount of time that I have.

Is there anyway to explain graphing easily to a beginner in Java?

回答1:

Use a Canvas as your drawing surface.

Use the drawLine() function to draw a line between X1,Y1 and X2,Y2.

There are lots of samples out there for this, such as: http://mainline.brynmawr.edu/Courses/cs110/fall2003/Applets/CanvasExample/CanvasExample.html

or this: http://www.java2s.com/Code/Java/2D-Graphics-GUI/Drawcanvaswithcolorandtext.htm

Laurence

回答2:

In my personal experience, the easiest way to draw lines in a GUI is to use a paint(Graphics g) method. Within that, use g.drawLine(x1,y1,x2,y2); to draw the line.

import javax.swing.*;
public class JGraph extends JPanel 
{
  public void paint(Graphics g)
  {
    g.drawLine(x1,y1,x2,y2);
  }
}

*On a side note, the coordinate system for this method starts at the top left of the GUI object of choice in the prior code.

回答3:

How do you search??

How to draw lines in Java

Short example

And search the API

Point

Graphics

回答4:

to draw ultimate lines I have figured out the following code:

public void drawUltimate(Graphics g, int x, int y, int x2, int y2){
    int ex=0,ey=0,ex2=0,ey2=0, mx, my;
    mx = x2-x;my = y2-y;
    //drawLine(jPanel1.getGraphics(), x, y, x2, y2);
    for (int i=0; i<100; i++){
        ex += mx;
        ey += my;

        drawLine(jPanel1.getGraphics(), ex2+1, ey2-2, ex, ey);
        ex2 =ex; ey2 =ey;
    }
}