Java problem, totally confused!

Hello guys :)

I am doing a course in Java and i have a small assignment to do, but i am totally confused about it :(

I am not very good with Java heh, i was wondering if anybody would be so kind as to help me with my problem?

I have to write an applet that will list integers 1 to 10, along with their square roots and the sum total. I have to implement the applet using a grid layout and a definite loop.

I have the basic code working that produces 1-10, square roots and the total, but i am totally lost trying to put them into a grid and i have no idea what a definite loop is!?

I also have to use different class names and convert the program to use a preconditioned loop and a post-conditioned loop.

If somebody would be so kind as to look over my code and suggest solutions to my problems i would be eternally grateful :)

import java.awt.Graphics;
import java.applet.Applet;

public class As2 extends Applet
{
int[] numbersArray={1,2,3,4,5,6,7,8,9,10}; //Initialise an array of numbers 1-10
public void paint(Graphics g)
{
int num;
int total = 0;
for(int i=0;i<10;i++)
{
num=numbersArray[i]; //'num' will be a number from the array, named 'i'
total=total+num;
System.out.println(""+(i+1)+" "+Math.sqrt(i+1)+" "+total);
}
g.drawString("Total is "+total,50,100);
}
}

Thankyou very much in advance for any assistance :)

Pyrastilia

A definate loop is one where the number of time it loops is specified (i.e. a for loop) an indefinate loops would be like a while loop.

anyways to like it up in a grid you the g.drawString and like things up. Heres what I did from your code. I think it is what you want but If not you can probably change it slightly to fit your needs.


import java.awt.Graphics;
import java.applet.Applet;

public class As2 extends Applet
{
int [] numbersArray = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; //Initialise an array of numbers 1-10
public void paint (Graphics g)
{
int num;
int total = 0;
int offset = 0;
for (int i = 0 ; i < 10 ; i++)
{
num = numbersArray [i]; //'num' will be a number from the array, named 'i'
total = total + num;
g.drawString (""+(i + 1), 0, 25 + offset);
g.drawString (""+Math.sqrt (i + 1), 50, 25 + offset);
g.drawString (""+total, 200, 25 + offset);
offset = offset + 25;
}
}
}

I guess this is your full code :

Code:

---

import java.applet.* ;
import java.awt.* ;

public class Sample extends Applet
{
  public void paint (Graphics g) {
    int total = 0 ;
    double totalSqr = 0.0 ;
    int y = 20 ;
    for (int i = 1 ; i <= 10 ; i++) {
      g.drawString(Integer.toString(i), 20, y) ;
      g.drawString(Double.toString(Math.sqrt(i)), 60, y) ;
      total += i ;
      totalSqr += Math.sqrt(i) ;
      y += 20 ;
    }
    g.drawLine(20, y - 10, getWidth(), y - 10) ;
    y += 10 ;
    g.setFont(new Font("Arail", Font.BOLD, 12)) ;
    g.drawString(Integer.toString(total), 20, y) ;
    g.drawString(Double.toString(totalSqr), 60, y) ;
  }
}

---

Hello guys :)

Thank you for the help previously, i am now more aware of exactly what i need to do.

I need to implement this code into a grid (11x2.... the first 10 rows are col#1 - the integers (1-10), col#2 - the square root of the number). The last row will be the sum total of the integers 1-10.

I need to run this program first with a definite loop, then preconditioned loop and finally a post-conditioned loop.

This is the code i have so far:

import java.awt.Graphics;
import java.applet.Applet;

public class As2 extends Applet
{
int[] numbersArray={1,2,3,4,5,6,7,8,9,10}; //Initialise an array of numbers 1-10
public void paint(Graphics g)
{
int num;
int total = 0;
for(int i=0;i<10;i++)
{
num=numbersArray[i]; //'num' will be a number from the array, named 'i'
total=total+num;
System.out.println(""+(i+1)+" "+Math.sqrt(i+1)+" "+total);
}
g.drawString("Total is "+total,50,100);
}
}

What i need to do is switch it around so it will display in the applet itself in a grid. I then need to convert it to use the 2 other types of loop.

If anybody would be able to help me with this i would be so grateful :)

Pyrastilia

heres a basic style of three types of loops

Code:

---

// The "ForAndWhile" class.
import java.applet.*;
import java.awt.*;

public class ForAndWhile extends Applet
{

    public void paint (Graphics g)
    {
        //for loop
        for (int x = 1 ; x <= 10 ; x++)
        {
            g.drawString (x + "", 25, x * 10);
        }
        //preconditional loop
        int y = 1;
        while (y <= 10)
        {
            g.drawString (y + "", 75, y * 10);
            y = y + 1;
        }
        //postconditional loop
        int z = 1;
        while (true)
        {
            if (z > 10)
            {
                break;
            }
            g.drawString (z + "", 125, z * 10);
            z = z + 1;
        }
    } // paint method
} // ForAndWhile class

---

_________________________________

for lining up in a grid check out the code i posted in the last message. you just need to use the g.drawString command, lining up the x values and offseting int y values

That is brilliant, thankyou.... the main problem i am having is trying to fit this lot into a 11x2 grid, no borders, using the setLayout(new GridLayout(11,2)); command (must be that command because we haven't learnt other ways lol)

If anybody could help with the setLayout(new GridLayout(,)); command and get all this into that applet that would be brilliant :) I can work on the loops from the advice given here, thankyou so much guys :)

Richard
xx

hmmm im not familiar with that command but i wll see what i can figure out

alright I think I have what you are looking for but I may bot be understanding exactly how u want it so heres what I've got.

Code:

---

// The "Layout" class.
import java.applet.*;
import java.awt.*;

public class Layout extends Applet
{
    public void init ()
    {
        int Sum = 0;
        setLayout (new GridLayout (11, 2));
        for (int x = 1 ; x <= 10 ; x++)
        {
            add (new Label (Integer.toString (x)));
            add (new Label (Double.toString (Math.sqrt (x))));
            Sum = Sum + x;
        }
        add (new Label (Integer.toString (Sum)));
    } // init method
} // Layout class

---

thats using a for loop so I will leave you to see if you can use other loops to do it with help from my above post

That is exactly what i've been after :)

Thankyou so much!

I'll work on getting this to work with the other types of loop so expect to hear from me again soon hehe

Pyra

no problem, im glad to help

Ok i have finished that assignment... now i have a new one! :P Advice with the coding would be greatly appreciated, i can see myself coming back here a lot to help people to return the favour :)

Anyway, my new assignment... (i have to use a text field and various other BASIC Java commands... i want to learn this, not only pass the course hehe)

1. You are required to write a program which calculates the circumference of a circle. The calculation should be done within the actionPerformed method.

2. Amend the program so that it is modularised by the use of a function method which uses the circle's radius as a parameter.

If anybody (TBeck... i'll give you a little man kiss lol... just kidding) could help me with the coding for this i would be eternally grateful :) (believe it or not, i am actually top of my class by quite a long way... just Java hasn't sunk in yet heh)

Pyra

PS I know the radius * Math.PI * 2 (or diameter = radius * 2, therefore circumference = diameter * Math.PI) command to find the circumference, i'm just not 100% sure how the two programs are supposed to vary.... god i like programming and coding, but Java bewilders me :P

i could get you started quickly before i go to work...
you could do something like this, u just need to add a textfield and stuff.

Code:

---

import java.awt.*;
  import java.awt.event.*;
  import java.applet.*;
 
  public class class1
      extends Applet
      implements ActionListener
  {
    private Button btnColor;
    private String[] strColors =
        { "White", "Yellow", "Green", "Pink" };
    private Color[] clColors =
        { Color.white, Color.yellow,
          Color.green, Color.pink };
    private int index;
 
    public void init ()
    {
      setBackground (Color.lightGray);
      index = 0;
      btnColor = new Button (strColors [index]);
      btnColor.setBackground (clColors [index]);
      btnColor.addActionListener (this);
      add (btnColor);
    }
 
    public void actionPerformed (ActionEvent event)
    {
      if (++index >= strColors.length)
        index = 0;
      btnColor.setLabel (strColors [index]);
      btnColor.setBackground (clColors [index]);
    }
  }

---

Thankyou TBeck :)

I'm starting to like you heh...

I'll play around with your code and it'll come in handy knowing the colour commands, but... going to see what i can do about switching it around to produce circle cirumferences, i knew what to do at the time but i always go brain dead when i actually go to do it lol

Pyra

yea the program changes the colors but the code you need is a similar structure with the actions. Glad to help again

Ok... i have the program fully working now, BUT i want to make a few little changes to it to make it a bit fancier and more versatile...

What i'd like to do is make the text entries labels so they will move with applet window resizing and everything will stay aligned. I've been playing about with labels and keep getting a blank screen, nothing appears until the window is resized, then it all starts multiplying and it just looks stupid heh.

Is there a simple way to make my labels appear upon running the applet and NOT multiply?

Secondly... how the hell do you tell the label where you want it to go!? They all come out in one single line lol

Pyra

Here is my fully working code:

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.math.*;

public class As3task1 extends Applet
implements ActionListener
{
TextField radField;
Double diameter;
Double circumference;
Double radius;


public void paint(Graphics g)
{
g.drawString("Enter the radius of your circle in the",220,60);
g.drawString("box below to find the circumference!",218,80);
g.drawString("The circumference of this circle is: "+circumference+" centimetres",210,125);
}

public void init()
{
radField = new TextField(15);
add(radField);
add (new Label ("centimetres"));
radField.addActionListener (this);
}

public void actionPerformed (ActionEvent event)
{
radius = Double.parseDouble(radField.getText());
diameter = radius * 2;
circumference = diameter * Math.PI;
repaint();
}
}

1: Labels are not supposed to multiply (and they don't if you use them properly)
2: There is something called Layout Managers (This is Java, not VB) you must pick the appropriate one

Code:

---

import java.applet.* ;
import java.awt.* ;
import java.awt.event.* ;

import javax.swing.* ;

public class As3task1 extends Applet implements ActionListener
{
  private TextField radField ;
  private Double circumference ;
  private Double radius ;

  public void paint (Graphics g) {
    g.drawString("Enter the radius of your circle in the", 40, 60) ;
    g.drawString("box below to find the circumference!", 40, 80) ;
    g.drawString("The circumference of this circle is: " + circumference +
                " centimetres", 40, 100) ;
  }

  public void init () {
    try {
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()) ;
    }
    catch (Exception ex) {}
    radField = new TextField(15) ;
    add(radField) ;
    add(new Label("centimetres")) ;
    radField.addActionListener(this) ;
  }

  public boolean isNumeric (String expression) {
    for (int i = 0 ; i < radField.getText().length() ; i++) {
      if (!Character.isDigit(radField.getText().charAt(i))) {
        return false ;
      }
    }
    return true ;
  }

  public void actionPerformed (ActionEvent event) {
    if (isNumeric(radField.getText())) {
      radius = Double.parseDouble(radField.getText()) ;
      circumference = 2 * radius * Math.PI ;
      repaint() ;
    }
    else {
      JOptionPane.showMessageDialog(this, "Input must be numeric", "Error",
                                    JOptionPane.ERROR_MESSAGE) ;
    }
  }
}

---

Thankyou for the code ComputerJy...

I compiled and ran your code but... it does exactly the same as my code does, but with a few new more advanced commands in it?

I'm looking to switch my g.drawString entries to labels so they will all stay in the same alignment as the TextField... it's purely a personal preference, the code listed in my last post is fine as it stands... it does the job.

Also been playing around trying to move the TextField down so it's underneath the first 2 lines of text but i'm totally lost there lol

Pyra

Sorry ComputerJy i just read through my last post and it doesn't sound particularly grateful heh

I can see your code is designed to list an error if the user enters invalid text, such as letters in a numerically orientated TextField... that is brilliant, thankyou... but if i submit that as my assignment it's going to be so obvious i didn't do it myself lol

All i'm trying to do is change my text from g.drawString to labels so it will all align nicely when you resize the window... my second task in this assignment i've been looking at recently (Amend the program so that it is modularised by the use of a function method which uses the circle's radius as a parameter) and it might aswell be written in cool teen East London talk, i'd understand it just as well! :)

Pyra

if don't want relative positioning then use this line in the init()

Code:

---

this.setLayout(null) ;

---

and to set the position of any component, use the following line before the "this.add"

Code:

---

JTextField jTextField1=new JTextField();
    jTextField1.setBounds(new Rectangle(22, 21, 64, 19)) ;

---

if u want to keep the g.drawString lines you can change them to use the getSize().width like this:

Code:

---

public void paint (Graphics g)
{
g.drawString ("Enter the radius of your circle in the", getSize ().width / 2 - 100, 60);
g.drawString ("box below to find the circumference!", getSize ().width / 2 - 100, 80);
g.drawString ("The circumference of this circle is: " + circumference + " centimetres", getSize ().width / 2 - 100, 125);
}

---

Hmm tried sticking that in my code in the places you specified but i just get errors i don't understand... :(

Bear in mind i had NEVER tried Java until a couple of months ago and only today did i start to take an interest in it... i'm a BASIC/HTML person, i like things to be simple lol.... only today have i started to take an interest in real coding... so bear with me please!

Please understand that you might aswell be talking Swahili, i'd understand just as well lol

Pyra

TBeck - my last post i replied before your post had arrived. I just checked your code, that is EXACTLY what i was after (again)... i'm not gay, but we could have a hands-off marriage if you like? I'm not coming to Canada either lol... fussy ******* that i am :P

Thankyou so much.... now onto task 2 of that assignment! I thought i should have a fairly good idea how to make this work but i had a quick look earlier and it is nowhere near as easy as i thought it'd be

which code didn't work?

Couldn't work out where you were coming from ComputerJy, sorry... no offence lol, i'm just new to Java and as i said before, it might aswell all be in Swahili.... i'm learning though!

Anyway... i've got my first program working fine, it works exactly how i want it to now. Task 2 is another question:

2. Amend the program so that it is modularised by the use of a function method which uses the circle's radius as a parameter

I'm trying to work on this but, at the end of the day, i haven't got a clue lol

Any advice would be greatly appreciated, my only clue is the calcArea command... which is obviously no use, in itself, as i don't need to find the area... i need the circumference!

This 2nd task should be done with the code from task 1, but modified to use a function method to use the circle's radius as a parameter.

Pyra

PS I hope this makes sense to somebody more than it does to be lol

PPS Task 1 code (task 2 MUST use this code for the aforementioned alteration)

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.math.*;

public class As3task1 extends Applet
implements ActionListener
{
TextField radField;
Double diameter;
Double circumference;
Double radius;

public void init()
{
radField = new TextField(15);
add(radField);
add (new Label ("centimetres"));
radField.addActionListener (this);
}

public void paint (Graphics g)
{
g.drawString ("Enter the radius of your circle in the", getSize ().width / 2 - 101, 60);
g.drawString ("box above to find the circumference!", getSize ().width / 2 - 103, 80);
g.drawString ("PLEASE ENTER ONLY NUMBERS WITH NO TEXT", getSize ().width / 2 - 140, 110);
g.drawString ("The circumference of this circle is: " + circumference + " centimetres", getSize ().width / 2 - 145, 145);
}

public void actionPerformed (ActionEvent event)
{
radius = Double.parseDouble(radField.getText());
diameter = radius * 2;
circumference = diameter * Math.PI;
repaint();
}
}

you mean like:

Code:

---

public double circumference(int radius){
    return Math.PI*radius*2;
  }

---

Ok been playing around with my task 2 code...

It compiles fine, it runs fine, there are no errors... but it doesn't return the circumference based on the radius i enter in the TextField? Nothing happens when i type into the text box lol

Please help!

NO ADVANCED JAVA CODE PLEASE LOL, I WANT TO LEARN WHAT I'M DOING NOT JUST COPY SOMEBODY ELSE!

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.math.*;

public class As3task2 extends Applet
implements ActionListener
{
TextField radField;
Double diameter;
Double circumference;
Double radius;

public void init()
{
radField = new TextField(15);
add(radField);
add (new Label ("centimetres"));
radField.addActionListener (this);
}

public void actionPerformed (ActionEvent event)
{
radius = Double.parseDouble(radField.getText());
repaint();
}

public double circumference(int radius)
{
return Math.PI*radius*2;
}

public void paint (Graphics g)
{
g.drawString ("Enter the radius of your circle in the", getSize ().width / 2 - 101, 60);
g.drawString ("box above to find the circumference!", getSize ().width / 2 - 103, 80);
g.drawString ("PLEASE ENTER ONLY NUMBERS WITH NO TEXT", getSize ().width / 2 - 140, 110);
g.drawString ("The circumference of this circle is: " + circumference + " centimetres", getSize ().width / 2 - 145, 145);
}

}

Pyra

PS Please... any suggestions/advice and/or alterations should use only code from my task 1 or task 2 lists, small additions are welcome but please i don't want anybody to rewrite my code because it would be a waste of time... this is 95% my own work and i'd like to keep it that way

Code:

---

import java.applet.* ;
import java.awt.* ;
import java.awt.event.* ;

import javax.swing.* ;

public class As3task1 extends Applet implements ActionListener
{
  private TextField radField ;
  private double radius=0.0 ;

  public void paint (Graphics g) {
    g.drawString("Enter the radius of your circle in the", 40, 60) ;
    g.drawString("box below to find the circumference!", 40, 80) ;
    g.drawString("The circumference of this circle is: " + circumference(radius) +
                " centimetres", 40, 100) ;
  }

  public void init () {
    try {
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()) ;
    }
    catch (Exception ex) {}
    radField = new TextField(15) ;
    add(radField) ;
    add(new Label("centimetres")) ;
    radField.addActionListener(this) ;
  }

  public double circumference(double radius){
    return Math.PI*radius*2;
  }

  public boolean isNumeric (String expression) {
    for (int i = 0 ; i < radField.getText().length() ; i++) {
      if (!Character.isDigit(radField.getText().charAt(i))) {
        return false ;
      }
    }
    return true ;
  }

  public void actionPerformed (ActionEvent event) {
    if (isNumeric(radField.getText())) {
      radius = Double.parseDouble(radField.getText()) ;
      repaint() ;
    }
    else {
      JOptionPane.showMessageDialog(this, "Input must be numeric", "Error",
                                    JOptionPane.ERROR_MESSAGE) ;
    }
  }
}

---

Thankyou ComputerJy :)

That is very advanced looking code to me lol, we haven't been studying anything like that... but i'll work on the code and see if i can come up with something that works using only my code...

Thing is, my applet works apart from the fact that TextField input doesn't register so there's no output... i'm working on it!

Pyra

Ok i now have both parts of my assignment working 100% exactly how i wanted them to (aside from the text box being at the top of the applet, but that's me being fussy lol)

I have to thank TBeck and ComputerJy. It only happened because of you 2, i was lost before i came here. Thankyou so much guys :)

Pyra

PS You'll see me again :)