The Ackermann function should be added in the code to draw the function\'s graph
ID: 3703598 • Letter: T
Question
The Ackermann function should be added in the code to draw the function's graph. Look at the bolded code the other part just builds the graphics.
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JTextField;
public class StudentExampleActionListener extends JApplet implements ActionListener
{
private static final long serialVersionUID = 1L;
private static int temp;
private static int count;
private static int countTotal = 0;
int forColor = 1;
int m, n;
boolean paint = false;
Font titleFont;
Font regularFont;
//*** two buttons are declared
JButton DrawLinesButton;
JButton clearLinesButton;
//*** two input values declared
JTextField inputLineNumber1;
JTextField inputLineNumber2;
Container contentPane;
//*** all JApplet have a method paint to draw the graphics
//*** Graphics object is brought in
//*** paint() is automatically called
public void paint (Graphics page)
{
if(!paint)
graphInitialize(page);
super.paint(page);
setBackground(Color.WHITE);
graph(page);
}
//*** The Applet class defines a method that is essential for programming applets,
//*** the init() method. This method is called just after the applet object has
//*** been created and before it appears on the screen. Its purpose is to give
//*** the applet a chance to do any necessary initialization. This method is
//*** called by the system, not by your program. Your job as a programmer
//*** is just to provide a definition of the init() method.
public void init()
{
System.out.println("init has been called");
contentPane = getContentPane();
contentPane.setLayout(null);
//*** 32 and 18 are pixel size
titleFont = new Font("Arial", Font.BOLD, 32);
regularFont = new Font("Arial", Font.PLAIN, 18);
//*** memory is allocated for Button
DrawLinesButton = new JButton("Draw Lines");
//*** this button is active and will be read
//*** by method actionPerformed(ActionEvent e)
DrawLinesButton.addActionListener(this);
//*** Location of button is created
DrawLinesButton.setBounds(350,550,150,40);
//*** memory is allocated for Button
clearLinesButton = new JButton("Clear Lines");
//*** this button is active and will be read
//*** by method actionPerformed(ActionEvent e)
clearLinesButton.addActionListener(this);
//*** Location of button is created
clearLinesButton.setBounds(350,600,150,40);
//*** setBounds() creates the input box
//*** memory is allocated for TextField
inputLineNumber1 = new JTextField(15);
//*** Location of TextField is created
inputLineNumber1.setBounds(210,560,50,30);
//*** memory is allocated for TextField
inputLineNumber2 = new JTextField(15);
//*** Location of TextField is created
inputLineNumber2.setBounds(210,590,50,30);
//*** add them to contentPane
contentPane.add(DrawLinesButton);
contentPane.add(clearLinesButton);
contentPane.add(inputLineNumber1);
contentPane.add(inputLineNumber2);
}
public void graphInitialize (Graphics page)
{
Graphics g = getGraphics();
Color c = getBackground();
g.setColor(c);
for(int x=0;x<1250;x++)
g.drawLine (x,900, x,0);
System.out.println("graphInitialize has been called");
page.setColor(Color.BLACK);
page.setFont(titleFont);
page.setFont(regularFont);
//*** Strings line up with setBounds for each JTextField
// page.drawString("Enter line number 1: ",40, 580);
// page.drawString("Enter line number 2: ",40, 610);
//*** initialize input to 0
inputLineNumber1.setText("0");
inputLineNumber2.setText("0");
}
public void graph(Graphics page)
{
System.out.println("graph has been called");
if(!inputLineNumber1.getText().equals("")&&!inputLineNumber2.getText().equals(""))
{
//*** text must be changed to int using the wrapper class Integer
int lineNumber1 = Integer.parseInt(inputLineNumber1.getText());
int lineNumber2 = Integer.parseInt(inputLineNumber2.getText());
//*** method called here
int result = drawLines(lineNumber1, lineNumber2, page);
//*** method called here
//*** 3 strings are placed in the window
page.setColor(Color.BLACK);
page.setFont(titleFont);
page.drawString("Practice Graph", 540, 50);
page.setFont(regularFont);
page.drawString("Number of lines: " + result, 600, 580);
page.drawString("Value of lines again: " + result, 600, 610);
page.drawString("Enter line number 1: ",40, 580);
page.drawString("Enter line number 2: ",40, 610);
}
}
private int drawLines(int lineNumber1, int lineNumber2, Graphics page)
{ //*********************************************************
//*** this method could be the recursive Ackermann function
//*********************************************************
count = 200;
countTotal = 0;
setNewColor(page,(int) (Math.random() * 12)+1);
for(int i=0;i<lineNumber1;i++)
{
page.drawLine (count,500, count,400);
count++;
countTotal++;
}
setNewColor(page,(int) (Math.random() * 12)+1);
for(int i=0;i<lineNumber2;i++)
{
page.drawLine (count,500, count,300);
count++;
countTotal++;
}
return countTotal;
}
private void setNewColor(Graphics page, int forColor)
{
switch (forColor)
{
case 1:
page.setColor(Color.BLACK);
break;
case 2:
page.setColor(Color.BLUE);
break;
case 3:
page.setColor(Color.CYAN);
break;
case 4:
page.setColor(Color.DARK_GRAY);
break;
case 5:
page.setColor(Color.GRAY);
break;
case 6:
page.setColor(Color.GREEN);
break;
case 7:
page.setColor(Color.LIGHT_GRAY);
break;
case 8:
page.setColor(Color.DARK_GRAY);
break;
case 9:
page.setColor(Color.MAGENTA);
break;
case 10:
page.setColor(Color.ORANGE);
break;
case 11:
page.setColor(Color.PINK);
break;
case 12:
page.setColor(Color.YELLOW);
break;
}
}
public void actionPerformed(ActionEvent e)
{
//*** buttons are active
String actionCommand = e.getActionCommand();
//*** one of two possible values of actionCommand
if (actionCommand.equalsIgnoreCase("Draw Lines"))
{
System.out.println("Draw Lines has been called");
paint = true;
countTotal = 0;
count = 0;
repaint();//*** method paint() is called again
}
else if (actionCommand.equalsIgnoreCase("Clear Lines"))
{
System.out.println("Clear Lines has been called");
this.clear();
inputLineNumber1.setText("");
inputLineNumber2.setText("");
}
}
public void clear()
{
//*** Graphics object is gotten
Graphics g = getGraphics();
Color c = getBackground();
g.setColor(c);
//*** lines of the background color cover up the image
for(int i=100;i<1250;i++)
g.drawLine (i,500, i,150);
for(int i=600;i<1000;i++)
g.drawLine (i,700, i,75);
}
}
Explanation / Answer
The algorithm for Ackermann function looks like below:
A(x, y) = y+1 when x = 0
= A(x-1, 1) when x > 0 and y = 0
= A(x-1, A(x, y-1)) when x > 0 and y > 0
Now, recursive method for ackermann function in java
//defining the ackermann function
public int ackermannFunction(int x, int y){
//method body
//case 1 when x = 0
if(x == 0) return y+1;
//case 2 when x >0 and y = 0
if(x > 0 && y == 0) return ackermannFunction(x - 1, 1);
//case 3 when x > 0 and y > 0
if(x > 0 && y > 0) return ackermannFunction(x - 1, ackermannFunction(x, y - 1));
}
Now replace the line count = 200 in the bolded code to below line
count = ackermannFunction(lineNumber1, lineNumber2);
Thankyou.
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