i am trying to drew a line using “*”

i am trying to drewan line using "*" in the console . but i get only 2 "*". i think something is wrong with the line algorithm . maybe there is an easier way to do it.

Code:

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class MyGraphicsApp {
        MyGraphicsApp() {mg = new MyGraphics(80, 25);}

        void paint(MyGraphics g) {
                g.drawLine(5, 12, 27, 2);
                g.drawLine(2, 2, 30, 30);
        }

        void repaint() {
                paint(mg);
                mg.display();
        }

        public static void main(String [] args) {
                MyGraphicsApp myGraphicsApp = new MyGraphicsApp();
                myGraphicsApp.repaint();
        }

        MyGraphics mg;
}

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Code:

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class MyGraphics {
int x, y;
        private int width, height;
        MyGraphics(int wid, int hit) {

                fb= new FrameBuffer(wid,hit);
                width = fb.getWidth();
                height = fb.getHeight();
        }
        MyGraphics() {
                fb = new FrameBuffer();
                width = fb.getWidth();
                height = fb.getHeight();
        }

void drawLine(int x1,int y1,int x2,int y2)
{
  width= x2 - x ;
    height = y2 - y ;
    int dx1 = 0, dy1 = 0, dx2 = 0, dy2 = 0 ;
    if (width<0) dx1 = -1 ; else if (width>0) dx1 = 1 ;
    if (height<0) dy1 = -1 ; else if (height>0) dy1 = 1 ;
    if (width<0) dx2 = -1 ; else if (width>0) dx2 = 1 ;
    int longest = Math.abs(width) ;
    int shortest = Math.abs(height) ;
    if (!(longest>shortest)) {
        longest = Math.abs(height) ;
        shortest = Math.abs(width) ;
        if (height<0) dy2 = -1 ; else if (height>0) dy2 = 1 ;
        dx2 = 0 ;
    }
    int numerator = longest >> 1 ;
    for (int i=0;i<=longest;i++) {
                fb.setPixel(x1, y1);

        numerator += shortest ;
        if (!(numerator<longest)) {
            numerator -= longest ;
            x += dx1 ;
            y += dy1 ;
        } else {
            x += dx2 ;
            y += dy2 ;
        }
    }
    return;
}
        void display() {
                fb.display();
                return;
                } // simply calls the frame buffer's display method

        FrameBuffer fb;
}



/*void drawLine(int x1,int y1,int x2,int y2)
{
  width= x2 - x ;
    height = y2 - y ;
    int dx1 = 0, dy1 = 0, dx2 = 0, dy2 = 0 ;
    if (width<0) dx1 = -1 ; else if (width>0) dx1 = 1 ;
    if (height<0) dy1 = -1 ; else if (height>0) dy1 = 1 ;
    if (width<0) dx2 = -1 ; else if (width>0) dx2 = 1 ;
    int longest = Math.abs(width) ;
    int shortest = Math.abs(height) ;
    if (!(longest>shortest)) {
        longest = Math.abs(height) ;
        shortest = Math.abs(width) ;
        if (height<0) dy2 = -1 ; else if (height>0) dy2 = 1 ;
        dx2 = 0 ;
    }
    int numerator = longest >> 1 ;
    for (int i=0;i<=longest;i++) {
                fb.setPixel(y, x);

        numerator += shortest ;
        if (!(numerator<longest)) {
            numerator -= longest ;
            x += dx1 ;
            y += dy1 ;
        } else {
            x += dx2 ;
            y += dy2 ;
        }
    }
    return;
}*/

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Code:

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public class FrameBuffer {
        FrameBuffer (int wid, int hit)
    {
      width = wid;
      height = hit;
        pixels = new boolean[height][width];

        for(int i = 0; i < height; i++){ // sets all positions in the array to false
            for(int j = 0; j < width; j++){
                pixels[i][j] = false;
            }
        }
    }        // Creates a frame buffer of specified resolution
        FrameBuffer () {
        height = 35;
        width = 60;
          pixels = new boolean[height][width];

        for(int i = 0; i < height; i++){ // sets all positions in the array to false
            for(int j = 0; j < width; j++) {
                pixels[i][j] = false;
            }
        }
    }        // Creates a default-sized frame buffer

 void setPixel(int x, int y, boolean b){
                pixels[y][x] = b;
        } //set pixels x,y to b
  void setPixel(int x, int y) {//position set as true

                pixels[y][x] = true;
        }        //set pixels x,y to true

    int getWidth() {
            return width;
            }
    int getHeight() {
            return height;
            }

    void clear() {

                for(int i = 0; i < height; i++)  {    //resets all positions to false
                        for(int j = 0; j < width; j++){

                                        pixels[i][j] = false;
                                }
                }
    } // clears the frame buffer

    void display() {

    System.out.print("+");      // left hand upper corner position on frame

    for( int i = 0; i < width; i++){ // loops through the first line on frame
            System.out.print("-");
        }
    System.out.println("+"); // right hand upper corner on frame

    for(int i = 0; i < height; i++) {    // loops through the entire frame till the last line
            System.out.print("|");
        int j;
    for(j = 0; j < width; j++){ // loops though each row falling out at the last position
        if(pixels[i][j] == true) { // prints and asterisk if true
          System.out.print("*");
        }
        else{
        System.out.print(" ");// otherwise prints a space
        }
      }
  System.out.println("|"); // before it increments i it prints out a "|"

    }
System.out.print("+");  // left lower corner position in the frame

    for(int i = 0; i < width; i++){// loops through the last line of the frame
            System.out.print("-");
        }

                System.out.println("+");  //right lower corner of the frame
    }

    private boolean pixels[][];
    private int width, height;
    public static void main(String [] args) {

            FrameBuffer fb = new FrameBuffer();
        int x = 0, y = 0;

        fb.display();
        while (x < fb.getWidth()) {
            while (x < fb.getWidth() && y < fb.getHeight()){
                fb.setPixel(x++, y++);

            }

        y--;

          while (x < fb.getWidth() && y >= 0){
                fb.setPixel(x++, y--);

          }
            if (y < 0)y = 0;
        }

        fb.display();
        fb.clear();

      fb.display();
    }
}

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Quote:

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i think something is wrong with the line algorithm

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Have you tried debugging the code by printing out the values of variables that control how many chars are shown?

What do you see when you execute your code? What is wrong with what it prints on the console?