My applet code compiles fine, however, I receive the "Applet Started" message every time. Please do not dissuade me from using AWT or Applets. I am simply trying to complete my assignment. Currently, my code is:
main method
import java.awt.*;
import java.awt.event.*;
public class Lab33ast
{
public static void main(String[] args)
{
Frame frame = new Frame("Lab33ast");
frame.add(new GfxApp());
frame.setSize(100, 750);
frame.addWindowListener(new WindowAdapter() {public void
windowClosing(WindowEvent e) {System.exit(0);}});
frame.setVisible(true);
}
}
Continued, I have a paint method in a separate file. GfxApp
import java.awt.*;
public class GfxApp extends Panel
{
private int td = 200; //Time Delay on graphics
public void paint(Graphics g)
{
g.setFont(new Font("Arial", Font.BOLD, 28));
g.drawString("Lab 33A 80/100 POINT VERSUIN", 300, 50);
g.setFont(new Font("Arial", Font.BOLD, 20));
g.drawString("DRAWING A LINKED LIST AS A STACK", 50, 215);
g.drawString("DRAWING A LINKED LIST AS A QUEUE", 50, 415);
drawStack(g);
drawQueue(g);
}
public void drawStack(Graphics g)
{
g.setFont(new Font("ARIAL", Font.BOLD, 20));
}
public void drawQueue(Graphics g)
{
g.setFont(new Font("ARIAL", Font.BOLD, 20));
}
}
Next I have a file called GfxNode that our teacher told us to add without further instruction.
import java.awt.*;
public class GfxNode
{
private int x; // x coordinate of node
private int y; // y coordinate of node
private final int width; // width of the gfx node
private final int height; // heigth of the gfx node
private final int time; // delay time between displays
// GfxNode constructor instantiates an object and
// stores its Top-Left coordinate (tlx,tly) information, as
// well as the length and width of the node object. A node object
// with two fields is drawn at the specified coordinate.
public GfxNode(Graphics g, int tlx, int tly, char ltr, int clr, int dt)
{
x = tlx;
y = tly;
width = 30;
height = 15;
time = dt;
drawNode(g,clr);
drawPointer(g,ltr,1,clr);
}
// Method drawNode is a private helper method to draw linked list nodes.
// This method draws a node with two fields at a location of the
// Top-Left coordinate information in the current object.
private void drawNode(Graphics g, int clr)
{
g.setColor(getColor(clr));
g.drawRect(x,y,width,height);
g.drawLine(x+height,y,x+height,y+height);
delay(time);
}
// Method getColor a private helper method to make it easier to use colors
// in a graphics program.
private Color getColor(int clr)
{
Color temp = Color.white;
switch (clr)
{
case 0: temp = Color.black; break;
case 1: temp = Color.red; break;
case 2: temp = Color.green; break;
case 3: temp = Color.blue; break;
case 4: temp = Color.orange; break;
case 5: temp = Color.cyan; break;
case 6: temp = Color.magenta; break;
case 7: temp = Color.yellow; break;
case 8: temp = Color.pink; break;
case 9: temp = Color.white; break;
}
return temp;
}
// Method getX returns the top-left X-coordinate of a linked list node.
public int getx()
{
return x;
}
// Method getY returns the top-left Y-coordinate of a linked list node.
public int gety()
{
return y;
}
// Method drawPointer draws a vertical pointer down to an existing node.
// The first pointer to a node uses OffSet value 1 and the second
// pointer to the same node uses OffSet value 2. The result is that
// the second pointer is moved farther to the right.
public void drawPointer(Graphics g, char ltr, int offSet, int clr)
{
if (offSet == 1)
offSet = 8;
else
offSet = 18;
int x1 = x + offSet;
int y1 = y - 20;
int x2 = x1;
int y2 = y - 2;
g.setColor(getColor(clr));
g.drawLine(x1,y1,x2,y2);
g.drawLine(x2,y2,x2-3,y2-3);
g.drawLine(x2,y2,x2+3,y2-3);
drawLetter(g,ltr,x+offSet-4,y-32);
delay(time);
}
// Method enterData draws a letter in the Data field of the GfxNode.
public void enterData(Graphics g, char ltr, int clr)
{
g.setColor(getColor(clr));
drawLetter(g,ltr,x+3,y+3);
delay(time);
}
// Method drawLink draws a link from the current sourceNode to the
// endNode in the specified color (clr).
public void drawLink(Graphics g, GfxNode endNode, int clr)
{
int x1,x2;
int y1 = this.gety() + height/2;
int y2 = endNode.gety() + height/2;
g.setColor(getColor(clr));
if (this.getx() < endNode.getx())
{
x1 = this.getx() + 22;
x2 = endNode.getx() - 2;
g.drawLine(x1,y1,x2,y2);
g.drawLine(x2,y2,x2-3,y2-3);
g.drawLine(x2,y2,x2-3,y2+3);
}
else
{
x1 = endNode.getx() + 8;
x2 = this.getx() + width + 2;
g.drawLine(x1,y1,x2,y2);
g.drawLine(x1,y1,x1-3,y1-3);
g.drawLine(x1,y1,x1-3,y1+3);
}
delay(time);
}
// Method drawNull draws a diagonal g.drawLine in the Next
// field of a list node, to indicate a NULL value.
public void drawNull(Graphics g, int clr)
{
g.setColor(getColor(clr));
g.drawLine(x+height+1,y+1,x+width-1,y+height-1);
delay(time);
}
// Method drawLetter upper-case Letter characters. The characters
// are drawn in a 9x9 pixel box.
// The (x,y) parameters indicate the coordinate of the top-left corner
// of the box. Only capital letters and numbers are drawn.
public void drawLetter(Graphics g, char ltr, int x, int y)
{
switch (ltr)
{
case 'A' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+4,x+8,y+4);
break;
case 'B' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+5,y);
g.drawLine(x,y+8,x+5,y+8);
g.drawLine(x,y+4,x+5,y+4);
g.drawLine(x+5,y,x+8,y+2);
g.drawLine(x+5,y+8,x+8,y+6);
g.drawLine(x+5,y+4,x+8,y+2);
g.drawLine(x+5,y+4,x+8,y+6);
break;
case 'C' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+8,x+8,y+8);
break;
case 'D' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+4,y);
g.drawLine(x,y+8,x+4,y+8);
g.drawLine(x+4,y,x+8,y+4);
g.drawLine(x+4,y+8,x+8,y+4);
break;
case 'E' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+8,x+8,y+8);
g.drawLine(x,y+4,x+6,y+4);
break;
case 'F' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+4,x+6,y+4);
break;
case 'G' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+6,y);
g.drawLine(x,y+8,x+8,y+8);
g.drawLine(x+8,y+8,x+8,y+4);
g.drawLine(x+8,y+4,x+4,y+4);
break;
case 'H' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y+4,x+8,y+4);
break;
case 'I' :
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+8,x+8,y+8);
g.drawLine(x+4,y,x+4,y+8);
break;
case 'J' :
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y+8,x+8,y+8);
g.drawLine(x,y+8,x,y+4);
break;
case 'K' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+1,y+4);
g.drawLine(x+8,y+8,x+1,y+4);
break;
case 'L' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y+8,x+8,y+8);
break;
case 'M' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y,x+5,y+5);
g.drawLine(x+8,y+1,x+4,y+4+1);
break;
case 'N' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y,x+9-1,y+8);
break;
case 'O' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+8,x+8,y+8);
break;
case 'P' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+4,x+8,y+4);
g.drawLine(x+8,y,x+8,y+4);
break;
case 'Q' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+8,x+8,y+8);
g.drawLine(x+3,y+5,x+8,y+10);
break;
case 'R' :
g.drawLine(x,y,x,y+8);
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+4,x+8,y+4);
g.drawLine(x+8,y,x+8,y+4);
g.drawLine(x,y+4,x+9,y+8);
break;
case 'S' :
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+4,x+8,y+4);
g.drawLine(x,y+8,x+8,y+8);
g.drawLine(x,y,x,y+4);
g.drawLine(x+8,y+4,x+8,y+8);
break;
case 'T' :
g.drawLine(x,y,x+8,y);
g.drawLine(x+4,y,x+4,y+8);
break;
case 'U' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+8);
g.drawLine(x,y+8,x+8,y+8);
break;
case 'V' :
g.drawLine(x,y,x+4,y+8);
g.drawLine(x+8,y,x+4,y+8);
break;
case 'W' :
g.drawLine(x,y,x,y+8);
g.drawLine(x+8,y,x+8,y+9-1);
g.drawLine(x,y+8,x+4,y+4);
g.drawLine(x+8,y+8,x+4,y+4);
break;
case 'x' :
g.drawLine(x,y,x+9,y+8);
g.drawLine(x,y+8,x+8,y);
break;
case 'y' :
g.drawLine(x,y,x+5-1,y+4);
g.drawLine(x+8,y,x+4,y+4);
g.drawLine(x+4,y+4,x+4,y+8);
break;
case 'Z' :
g.drawLine(x,y,x+8,y);
g.drawLine(x,y+8,x+8,y+8);
g.drawLine(x+8,y,x,y+8);
break;
default :
g.fillRect(x,y,8,8);
}
}
// Method delay allows viewing the sequence in which the linked lists are drawn/
private void delay(double n)
{
for (double k = 1; k < n; k+=0.00001);
}
}
I have no idea what the above code is about or its relation to my objective. Feel free to explain it to me.
I have created another class called GfxApplet and pointed to .htm code to it.
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
public class GfxApplet extends Applet
{
@Override
public void init()
{
super.init();
GfxApp app = new GfxApp();
add(app);
}
}
My html
<html>
<head>
</head>
<body bgcolor="000000">
<center>
<applet
code = "Lab33ast.class"
width = "500"
height = "300"
>
</applet>
</center>
</body>
</html>
If anyone can give specific and detailed solutions, I would much appreciate it.
There's no Applet in your code (nothing extends from Applet).
Generally speaking you should start with a different container class, maybe Panel (since you're living in the dark ages with AWT), put all your logic into this class.
Then, when you need it, create an instance of Frame or make a class which extends from Applet and add an instance of your panel to it.
Unless you have a major driving cause to, I'd avoid using AWT directly in this way and would use Swing, Swing superseded AWT 16+ years ago, so you're likely to get better community support. See Creating a GUI With JFC/Swing for more details
Since applets are been actively blocked by most browsers now days, I'd also question their use here
Missed the "Please do not dissuade me from using AWT or Applets" disclaimer
I see the logic in extending an applet. I just have no idea where to where to put that "extends Applet" part. As I change what is extended from GfxApp, I receive numerous errors in my main method, most commonly at "gfx.addWindowListener(new WindowAdapter()". My IDE says that it cannot find symbol
Move your core logic to a Panel based class
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Panel;
public class GfxApp extends Panel {
private int td = 200; //Time Delay on graphics
public void paint(Graphics g) {
g.setFont(new Font("Arial", Font.BOLD, 28));
g.drawString("Lab 33A 80/100 POINT VERSUIN", 300, 50);
g.setFont(new Font("Arial", Font.BOLD, 20));
g.drawString("DRAWING A LINKED LIST AS A STACK", 50, 215);
g.drawString("DRAWING A LINKED LIST AS A QUEUE", 50, 415);
drawStack(g);
drawQueue(g);
}
public void drawStack(Graphics g) {
g.setFont(new Font("ARIAL", Font.BOLD, 20));
}
public void drawQueue(Graphics g) {
g.setFont(new Font("ARIAL", Font.BOLD, 20));
}
}
Create a class which extends from Applet, add an instance of GfxApplet to it...
import java.applet.Applet;
public class GfxApplet extends Applet {
@Override
public void init() {
super.init();
GfxApp app = new GfxApp();
add(app);
}
}
Change your applet html code to point to it...
<html>
<head>
</head>
<body bgcolor="000000">
<center>
<applet
code = "GfxApplet.class"
width = "500"
height = "300"
>
</applet>
</center>
</body>
</html>
And if you need it, you can add GfxApp to an instance of Frame when you need to...
public static void main(String[] args) {
Frame frame = new Frame("Lab33ast");
frame.add(new GfxApp());
frame.setSize(100, 750);
frame.addWindowListener(new WindowAdapter() {
public void
windowClosing(WindowEvent e) {
System.exit(0);
}
});
frame.setVisible(true);
}
This is the basic of good management of your UI code