Java Programming Forums - The Java Community - What's Wrong With My Code?

Multiple Java Programs That I need Help with

frenchsasha — Sat, 25 May 2013 06:23:57 GMT

Question 1:

What is the output of the following code?

Code :

public class Question02b{
       public static void main(String[] args){ SuperClass superA = new
           SuperClass(); SuperClass superB = new SubClass(); SubClass
           sub = new SubClass(); System.out.println(superA.method());
           System.out.println(superB.method());
           System.out.println(sub.method());
           System.out.println(superB.method(1));
           System.out.println(superB.method(1.4));
}}
   class SuperClass { public static String method(){
           return "SuperClass"; } public String method(double a){
    return "SuperClass"; } }
   class SubClass extends SuperClass{ public static String method(){
           return "SubClass";
}
public String method(int a){
    return
"SubClass"; } }
Question 3 is on page 4

Question 2:
What are the possible types of objects at runtime that veg in the method omnivore may be pointing
to? And what would the output be?

Code :

public class Question03 { void omnivore(Vegetable veg){ veg.eat(); } }
    abstract class Vegetable { protected int roots = 7; public void eat(){
        slice(); saute(); } public static void saute(){
        System.out.println("Sizzle!"); } public abstract void slice();
}
    class Tuber extends Vegetable { Tuber(){ mash(); } public void slice(){
        System.out.println("Chop!"); mash();} public void mash(){
        System.out.println("Glop! " + roots); }
}
    class Potato extends Tuber
        { Potato(){ roots = 59; }
        public void eat(){
if(this.equals(new Potato())) System.out.println("Spud!"); else
    System.out.println("Spudless!");
            super.eat(); } public static void saute(){
        System.out.println("Crisps!"); } public void mash(){
        System.out.println("Creamy! " + roots); }
}

Question 3:
There are two errors in this class, what are they and how can they be fixed?

Code :

public class Question04c extends OtherClass{
protected int answer(int i) throws DumbQuestionException { if(i < 0){ throw
    new DumbQuestionException(); } else return 6; } }
class OtherClass{ public int answer(int i){ return i; } }
    class DumbQuestionException extends Exception{ }

Please help with my new memory board game excercise, been trying for 1 whole week and still can't finish this..:(

jnesha1990 — Sat, 25 May 2013 04:47:05 GMT

Create an application with following requirements:
Input the length and width of board game manually.
Width must be an even number, and the max width must be equal to 40/length. For example: length input is 10, thus the maximum input number for width is 4.
The maximum size for memory board game (length*width) is 40
Program will do randomize symbols inside �Memory Board Game� for each square board. There will be only 2 same symbols for each symbol picture.
User will be ask to guess the location of 2 match symbol inside �Memory Board Game�.
User gets only 10 chances to guess all the match symbols.
If user guess correctly, the symbols will be opened.
If user guess wrongly, the chance will be deducted by one.
If user finish the chance before guessing all the match symbol, show a message of �You Lose�.
If user able to guess all the match symbols with available chance, show a message of �You Win�
Show user�s score with following formula:
Score = chance * grade
Grade = opened symbols * 10
By the end of game, prompt user if she/he wants to re-play the game.

hello ,have a good day all , i need some answers of these questions...

sahin11 — Sat, 25 May 2013 04:25:27 GMT

1. Operator effect definition:
oi,j ((a1 , a2 , . . . , a12 )) = (b1 , b2 , . . . , b12 )
k = 1, 2, . . . , 12
if (a1 , a2 , . . . , a12 ) ∈ dom(oi,j )
bk =
ak + j
ak + 120
if ∃l(al > ak ) ∨ (ak + ai = 0)
otherwise
Exercise 4. Create the Java implementation for the function above as a body of a void function!
We suppose that a1 , a2 , . . . , a12 are integers, and they are accessible in the function body as a[1], a[2],
. . ., a[12], and b1 , b2 , . . . , b12 are integers, and they are accessible in the function body as b[1], b[2], . . .,
b[12].

answer :

2.

Set of operators:
O = {o1,2 , o1,3 , o2,1 , o2,3 , o3,1 , o3,2 }
Domain of operators:
dom(oi,j ) = {(a1 , a2 , . . . , a12 ) ∈ N12 | ∀k((k = j) ⊃ (ak + i > aj )) ∧ ∃k∃l(a1 = ak ∗ al )}
Exercise 3. Create the Java implementation for the preconditions above as a body of a boolean
function! We suppose that a1 , a2 , . . . , a12 are integers, and they are accessible in the function body as a[1],
a[2], . . ., a[12].

answer :

3.

Set of goal states:
G = {(a1 , a2 , . . . , a12 ) ∈ N12 | ∀i∃j((ai + aj > 20) ⊃ (ai ∗ aj < 200))}
Exercise 2. Create the Java implementation for the goal condition above as a body of a boolean
function! We suppose that a1 , a2 , . . . , a12 are integers, and they are accessible in the function body as a[1],
a[2], . . ., a[12]

answer :

4.

∀i(∃j((aj < ai ) ∨ (aj = 1000)) ⊃ (ai > 0) ∨ ∃j(aj = 50))
where i ∈ {1, 2, . . . , 6} and j ∈ {1, 2, . . . , 6}
Exercise 1. Create the Java implementation for the formula above as a body of a boolean
function! We suppose that a1 , a2 , . . . , a6 are integers, and they are accessible in the function body as a[1],
a[2], . . ., a[6].

answer :

5.

1.all i exists j a[i] > a[j] or a[1] = a[4]

all i ( exists j ( (a[j] < a[i]) or not (a[j] = 1000) ) implies ( a[i] > 0 or exists j ( a[j] = 50 ) ) )

implementation in java :

------------------------------------------------------------------------------------------------

Complete the Java implementation of the Breadth-first search

Exercise 1. Initialize the database.
Exercise 2. Construct the solution as an operator list.
Exercise 3. Complete the code of the extension.
❜
public interface Problem {
State startState();
Collection operators();
}
public interface State {
boolean isGoal();
}
public interface Operator {
boolean isApplicable(State s);
State apply(State s);
❜
}

public abstract class Solver {
private static class Node {
State state;
Operator creator;
Node parent;
int deep;
public Node(State state, Operator op, Node parent ) {
this.deep = parent == null ? 0 : parent.deep + 1;
this.creator = op;
this.parent = parent;
this.state = state;
}
❜
}
public List run(Problem p) {
LinkedList closedNodes = new LinkedList();
LinkedList openNodes = new LinkedList();
/* Exercise 1: Initialize the database. */

while ( ! openNodes.isEmpty() ) {
Node node = openNodes.removeFirst();
if ( node.state.isGoal() ) {
LinkedList solution = new LinkedList();
/* Exercise 2: Construct the solution as an operator list. */

return solution;
}
closedNodes.add(node);
for ( Operator op : p.operators() ) {
if ( op.isApplicable(node.state) ) {
State newState = op.apply(node.state);
/* Exercise 3: Complete the code of the extension

* (use the search function below when necessary). */
}
}
}
return null;
}
private static Node search(List nodeList, State state) {
for ( Node node : nodeList )
if ( state.equals(node.state) )
return node;
return null;
}
}

Problems with sockets on simple server and client programs.

gongshow20 — Fri, 24 May 2013 21:13:58 GMT

I set up a simple text message server and client using sockets. When I am have both programs running and connected then close the client without inputting "TERMINATE" I can't connect another client. This is the error stack I'm getting when I close the client.

java.net.BindException: Address already in use: JVM_Bind
at java.net.DualStackPlainSocketImpl.bind0(Native Method)
at java.net.DualStackPlainSocketImpl.socketBind(Unkno wn Source)
at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.(Unknown Source)
at java.net.ServerSocket.(Unknown Source)

I get this error when I have my server and client programs open. I then close the client window, and this error is when a new ServerSocket is created when the runServer() is called in the closeConnection() method is called. When this happens my connection still has a Socket value. How can I properly handle a client termination so another client can connect.

Another question dealing with threading. At this point I cannot connect more than one client at a time. I know I need to create a thread that handles connecting clients, so I can have multiple clients communicating with each other. I am not sure how to implement this.

Here is my server class.

Code :

public class Server extends JFrame {
 
	private JTextField enterField;
	private JTextArea displayArea;
	private ObjectOutputStream output;
	private ObjectInputStream input;
	private ServerSocket server;
	private Socket connection;
	private int counter = 1;
 
	public Server() {
		super ("Server");
		enterField = new JTextField();
		enterField.setEditable(true);
		enterField.addActionListener(new ActionListener() {
 
			@Override
			public void actionPerformed(ActionEvent event) {
				sendData(event.getActionCommand());
				enterField.setText("");
 
			}
		});
 
		add(enterField, BorderLayout.NORTH);
		displayArea = new JTextArea();
		add (new JScrollPane(displayArea));
		setSize(300,150);
		setLocation(500,500);
		setVisible(true);
	}
 
 
 
	public void runServer() {
		try {
			server = new ServerSocket(50499, 100);
			if(!server.isClosed()){
			displayMessage("\n Listening on Port: " + server.getLocalPort() + "\n");
 
			}
			while (true) {
				try {
					waitForCommunication();
					getStreams();
					processConnection();
				} catch (EOFException eofException) {
					displayMessage("\n Server terminated connection ");
				} finally {
					closeConnection();
					++counter;
				}
			}
		} catch (IOException ioException) {
			ioException.printStackTrace();
		}
	}
 
	private void closeConnection() {
		displayMessage("\nTerminating connection\n");
		setTextFieldEditable(false);
		try {
			output.close();
			input.close();
			connection.close();
		} catch (IOException ioException) {
			ioException.printStackTrace();
		}
		runServer();
 
	}
 
	private void displayMessage(final String string) {
		SwingUtilities.invokeLater(new Runnable(){
 
			@Override
			public void run() {
				displayArea.append(string);
			}
 
		});
 
	}
 
	private void processConnection() throws IOException {
		String message = "Connection Sucessful";
		sendData(message);
 
		setTextFieldEditable(true);
 
		do {
			try {
				message = (String) input.readObject();
				displayMessage("\n" + message);
			} catch (ClassNotFoundException classNotFoundException) {
				displayMessage("\nUnknown object type recieved");
			}
		} while (!message.endsWith(">>> TERMINATE"));
	}
 
	private void setTextFieldEditable(final boolean editable) {
		SwingUtilities.invokeLater(new Runnable(){
 
			@Override
			public void run() {
				enterField.setEditable(editable);
 
			}
 
		});
 
	}
 
	private void getStreams() throws IOException {
		output = new ObjectOutputStream(connection.getOutputStream());
		output.flush();
 
		input = new ObjectInputStream(connection.getInputStream());
 
		displayMessage("\nGOt I/O stream \n");
 
	}
 
	private void waitForCommunication() throws IOException {
		displayMessage("Waiting for cennection \n");
		connection = (server.accept());
		displayMessage("Connection" + counter + " received from: "
				+ connection.getInetAddress().getHostName());
	}
 
	private void sendData(String message) {
		try {
			output.writeObject("SERVER>>> " + message);
			output.flush();
			displayMessage("\nSERVER>>> " + message);
		} catch (IOException ioException){
			displayArea.append("\nError Writing Object");
		}
	}
}

Doing my head in! "for" loops

jess91 — Fri, 24 May 2013 19:38:20 GMT

Hey, i'm stuck on a code. In terms of formatting it is printing out what i need, but the final degree values are displaying all the same. each new 'carbon value' should create a new value for the surface temperature. my equation is correct, but the code to get it to pick up the right carbon value I just cant figure out....

Code java:

public class StageFour
{
      public static void main(String[] args)
      {
          //Adding Carbon
          //Problem Parameters
          final double SOLAR_CONSTANT = 1367.0;
          final double ALBEDO = 0.3;
          final double STEFANBOLTZMANN = 5.67E-8;
          final double ORBITAL_RADIUS = 1.0;
 
          //Declare Variable
          double surfaceTemperature; 
          int number;        
 
          //Create a decimal format object
          DecimalFormat df = new DecimalFormat("#0.00");
 
         //Equation.
          for (number = 280; number <= 400; number += 5)
          {
              surfaceTemperature = Math.pow((((SOLAR_CONSTANT/4)*(1.0 - ALBEDO))/(STEFANBOLTZMANN*(1.0 - (0.65 + (0.1 + 0.06*Math.log((number)/280)))/2)*(ORBITAL_RADIUS*ORBITAL_RADIUS))), 0.25) - 273.15;
              System.out.println("For a Carbon Level of " + number + " the Earth's Surface Temperature is " + (df.format(surfaceTemperature)) + "\u00b0" );
          }
      }
}

I should be getting lines printed from 280 to 400 with increments of 5, calculating eachof these numbers into my formula to get the appropriate degrees. on paper the equation works..

I should get something that spits numbers out like
For a Carbon Level of 280 the Earth's Surface Temperature is 13.49�
For a Carbon Level of 285 the Earth's Surface Temperature is 13.55�
For a Carbon Level of 290 the Earth's Surface Temperature is 13.61�
For a Carbon Level of 295 the Earth's Surface Temperature is 13.67� etc

but it just spits out all the same degrees values of 13.49 for each carbon level number.

Is anyway able to point out where I have gone wrong in my coding? I cant find any examples to help me out..

Cheers guys :)

Java Image Displayer

coderxx0 — Fri, 24 May 2013 11:13:55 GMT

I am having trouble with my code it is a java image dis-player and i cannot get it to work andi am completely stuck can somebody helpme

Code :

/*
   Copyright 2013 Matthew Kowal 
*/
 
package GUI;
 
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Graphics2D;
 
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.GroupLayout;
import javax.swing.GroupLayout.Alignment;
 
 
@SuppressWarnings("serial")
public class MainAppFrame extends JFrame {
 
    private JPanel contentPane;
    File targetFile;
    BufferedImage targetImg;
    public JPanel panel,panel_1;
    private static final int baseSize = 128;
    private static final String basePath =![enter image description here][1]
            "C:\\Documents and Settings\\Administrator\\Desktop\\Images";
 
    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    MainAppFrame frame = new MainAppFrame();
                    frame.setVisible(true);
                    frame.setResizable(false);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }
 
    /**
     * Create the frame.
     */
    public MainAppFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 550, 400);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(new BorderLayout(0, 0));
 
        panel = new JPanel();
        panel.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 0, 0), 1, true));
        contentPane.add(panel, BorderLayout.WEST);
 
        JButton btnBrowse = new JButton("Browse");
        btnBrowse.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                browseButtonActionPerformed(e);
            }
        });
 
        JLabel lblSelectTargetPicture = new JLabel("Select target picture..");
 
        JButton btnDetect = new JButton("Detect");
        btnDetect.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
 
        JButton btnAddDigit = new JButton("Add Digit");
        btnAddDigit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
 
        JButton button = new JButton("Recognize");
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
 
        panel_1 = new JPanel();
        panel_1.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 0, 0), 1, true));
 
        GroupLayout gl_panel = new GroupLayout(panel);
        gl_panel.setHorizontalGroup(
            gl_panel.createParallelGroup(Alignment.LEADING)
                .addGroup(gl_panel.createSequentialGroup()
                    .addGap(6)
                    .addGroup(gl_panel.createParallelGroup(Alignment.LEADING)
                        .addGroup(gl_panel.createSequentialGroup()
                            .addComponent(lblSelectTargetPicture)
                            .addGap(6)
                            .addComponent(btnBrowse))
                        .addGroup(gl_panel.createSequentialGroup()
                            .addGap(10)
                            .addComponent(btnDetect)
                            .addGap(18)
                            .addComponent(btnAddDigit))))
                .addGroup(gl_panel.createSequentialGroup()
                    .addGap(50)
                    .addComponent(button))
                .addGroup(gl_panel.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, 182, GroupLayout.PREFERRED_SIZE))
        );
        gl_panel.setVerticalGroup(
            gl_panel.createParallelGroup(Alignment.LEADING)
                .addGroup(gl_panel.createSequentialGroup()
                    .addGroup(gl_panel.createParallelGroup(Alignment.LEADING)
                        .addGroup(gl_panel.createSequentialGroup()
                            .addGap(7)
                            .addComponent(lblSelectTargetPicture))
                        .addGroup(gl_panel.createSequentialGroup()
                            .addGap(3)
                            .addComponent(btnBrowse)))
                    .addGap(18)
                    .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, 199, GroupLayout.PREFERRED_SIZE)
                    .addGap(22)
                    .addGroup(gl_panel.createParallelGroup(Alignment.BASELINE)
                        .addComponent(btnDetect)
                        .addComponent(btnAddDigit))
                    .addGap(18)
                    .addComponent(button)
                    .addContainerGap())
        );
 
        panel.setLayout(gl_panel);
    }
    public BufferedImage rescale(BufferedImage originalImage)
    {
        BufferedImage resizedImage = new BufferedImage(baseSize, baseSize, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = resizedImage.createGraphics();
        g.drawImage(originalImage, 0, 0, baseSize, baseSize, null);
        g.dispose();
        return resizedImage;
    }
    public void setTarget(File reference)
    {
        try {
            targetFile = reference;
            targetImg = rescale(ImageIO.read(reference));
        } catch (IOException ex) {
            Logger.getLogger(MainAppFrame.class.getName()).log(Level.SEVERE, null, ex);
        }
 
        panel_1.setLayout(new BorderLayout(0, 0));
        panel_1.add(new JLabel(new ImageIcon(targetImg))); 
        setVisible(true);
    }
    private void browseButtonActionPerformed(java.awt.event.ActionEvent evt) {
        JFileChooser fc = new JFileChooser(basePath);
        fc.setFileFilter(new JPEGImageFileFilter());
        int res = fc.showOpenDialog(null);
        // We have an image!
        try {
            if (res == JFileChooser.APPROVE_OPTION) {
                File file = fc.getSelectedFile();
                setTarget(file);
            } // Oops!
            else {
                JOptionPane.showMessageDialog(null,
                        "You must select one image to be the reference.", "Aborting...",
                        JOptionPane.WARNING_MESSAGE);
            }
        } catch (Exception iOException) {
        }
 
    }
}
 
 
 
 
//JPEGImageFileFilter.java
 
package GUI;
 
import java.io.File;
 
import javax.swing.filechooser.FileFilter;
 
/*
* This class implements a generic file name filter that allows the listing/selection
* of JPEG files.
*/
public class JPEGImageFileFilter extends FileFilter implements java.io.FileFilter
 {
 public boolean accept(File f)
   {
   if (f.getName().toLowerCase().endsWith(".jpeg")) return true;
   if (f.getName().toLowerCase().endsWith(".jpg")) return true;
   if(f.isDirectory())return true;
   return false;
  }
 public String getDescription()
   {
   return "JPEG files";
   }

Need Help With My Task

pumpkins — Fri, 24 May 2013 07:19:25 GMT

Hi everybody,
This is my task.I try to solve this problem but I couldnt understand nothing about print out part.

//Write a main method which creates a new property object with id 0, price 550000, area 2100 and availability true.
Print out its area in meters squared and then display the string form of the property object.//

This my working.What is wrong in this code ?
public class Property {
private double id;
private double price;
private double area;
private boolean availability;
public void propertyAttributes()
{
System.out.println("id,price,area,availability"+id +price+area+availability);
}

public Property ()
{
id=0;
price=550000;
area=2100;
availability=true;
}
public static void main(String[]args)
{
Property house=new Property();
house.propertyAttributes();
}
}

[SOLVED] GUI user input error message

deeevo — Fri, 24 May 2013 06:24:56 GMT

I need help implementing the below code. It currently is the code for a search bar. User enters in keywords and then it matches it against the recipe, returning true if so. It then displays the recipes matching in the interface. However, I want to implement an error message for invalid input. Currently with the below code it just brings up the error regardless, I added a break, but then it removed all the content from the interface. else if(recipe.foundWords(keys)) =! true) //do stuff ? is another option I tried.
Obviously not the result I'm wanting.

Code java:

            for(CakeRecipe recipe : recipeSet.getAllCakeRecipes()) 
            {
                if(recipe.foundWords(keys)) 
                {
                    searchRecipe.add(recipe);
                }
                else
                {
                    JOptionPane.showMessageDialog(this,"No recipe containing search words found.", "Error!",
                                                    JOptionPane.ERROR_MESSAGE);
                }
 
            }

Suggestions?

A different code runs

chized — Fri, 24 May 2013 02:55:40 GMT

hello friends, need ur help, dnt knw what's wrong. A different code runs(i.e a code i ran previously) instead of the present code on my editor that i tried running after coding. here is the present code

Code java:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class gui11 extends JPanel{
	public void paintComponent(Graphics g){
		super.paintComponent(g);
		this.setBackground(Color.WHITE);
 
		g.setColor(Color.BLUE);
		g.drawLine(10, 25, 200, 45);
 
		g.setColor(Color.RED);
		g.drawRect(10, 55, 100, 30);
 
		g.setColor(Color.GREEN);
		g.fillOval(10, 95, 100, 30);
 
		g.setColor(Color.ORANGE);
		g.fill3DRect(10, 160, 100, 50, true);
 
 
	}
 
}

the previous code that wouldnt stop running is

Code java:

package gui;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class Gui10 extends JPanel{
 
	public void paintComponent(Graphics g){
		super.paintComponent (g);
		this.setBackground(Color.WHITE);
 
		g.setColor(Color.BLUE);
		g.fillRect(25, 25, 100, 30);
 
		g.setColor(new Color(190,81,215));
		g.fillRect(25, 65, 100, 30);
 
		g.setColor(Color.RED);
		g.drawString("this is some text", 25, 120);
 
	}
 
 
}

i'll be gratefull to knw the cause soln, both code are same package. thanks!

Logic-Factory Pattern

hemakarthik — Fri, 24 May 2013 02:36:17 GMT

Hi,

we are creating the Common Engine in java to handle the all web service request.
In that engine contains,
session and reference data both values are maintain for all request and for all prj..
Process Factory to handle all process related to every prj..

Each time, will they request to hit the engine or process factory..?

What is purpose of creating the Factory class..how we have to utilize better?

Passed array value is null

NoobException — Fri, 24 May 2013 00:37:05 GMT

2nd part of a homework project which we have strict instructions. In the first part, I have another class which builds an Array of Country objects, which I use to create a Stack. Then the Stack values are supposed to be inserted into the priority Que and sorted alphebetically. Either my stack is not passing the objects correctly, or for whatever reason the priority Que is not receiving them correctly. When I print the array in pQue1 and pQue 2 it returns

null

thanks for any help!

I am very new to java and programming, but from past experiences I feel like the problem lies somewhere in creating the arrays, or somehow I have programmed the methods to pass the array to a completely different instance of priorityQueue??

Code :

import java.util.Arrays;
 
public class Stack {
private int maxSize;        // size of stack array
private Countries[] stackArray;  //  recall:  �instance variables�
private int top;            // top of stack
private PriorityQueue pQue1; 
private PriorityQueue pQue2; 
 
public Stack(int s)         
  {                
  maxSize = s;             
  stackArray = new Countries[maxSize];           
  top = -1; 
  pQue1 = new PriorityQueue(maxSize);
  pQue2 = new PriorityQueue(maxSize);
 
  } // end constructor
 
  public void push(Countries j)  
  {
  // put item on top of stack
  stackArray[++top] = j;
  System.out.println(stackArray[top]);     
 
  if (stackArray[top].getRegionNumber() == 1 )
      buildPQue1(stackArray[top]);
      pQue1.insert(stackArray[top]);
 
  if  (stackArray[top].getRegionNumber() == 2 )
      buildPQue2(stackArray[top]);
  } // end push
 
  public void buildPQue1(Countries k)
  {         
      pQue1.insert(k);         
  } // end build PQue1()
 
  public void buildPQue2(Countries i)
  {
     pQue1.insert(i);         
  } // end build P Que 2
  // end push()
 
 
 
 
public class PriorityQueue extends Queue
{    // array in sorted order, from max at 0 to min at nitems-1
private int maxSize;
private Countries[] queArray;
private Countries[] item;
private int nItems;
 
 
  public PriorityQueue(int s)    
  {      // constructor             
  super(s);
  maxSize = s;
  queArray = new Countries[maxSize];
  item = new Countries[maxSize];
  }//end constructor
 
  @Override
  public void insert(Countries item)  {     
  int j;                
  if (nItems==0)                           
  {
      queArray[nItems++] = item; 
     // System.out.println(queArray[nItems]);
  }// end if
  else                                         
  {                     
     for (j=nItems-1; j>=0; j--)    
     {
         if (item.getName().compareTo(queArray[j].getName()) < 0 )                                
           queArray[j+1] = queArray[j];                   
        else                                                      
           break;                                            
     } // end for
     if ( j < maxSize)
     {
     queArray[j+1] = item;                                           
     } // end if
       // System.out.print(queArray[j]);
     nItems++;                                                         
 
}  // end else (nItems > 0)          
}  // end insert()
 
public Countries peekMin()            // peek at minimum item
{ 
return queArray[nItems-1]; 
} // end peek min
 
 
public void displayQue()
{
System.out.println(queArray[nItems]);
} // end display que
 
}  // end class PriorityQ

Downcasting/Inheritance

john2454 — Fri, 24 May 2013 00:24:03 GMT

Ok need some help. I am new to this site. So not sure best approach.

I have a super class(Shapes), sub class(rectangle) and sub sub class (Box). I need to be able to print the shapeType for the two subclasses. I believe I need to use down casting. however I've attempted and failed! :mad:

I am not sure best way to share code. So I think I have it attached correctly.

help.txt

Attached Files

help.txt (6.6 KB)

JRadioButton Won't Respond

SynergY — Thu, 23 May 2013 20:26:08 GMT

Hello!
So my problem is that my radio buttons are not responding when I click them. I made sure there was an ActionListener, and I think my if statements are fine. So I'm pretty lost as to why they aren't doing their job.

In case my code is vague, I want the radio buttons to change the color of the font when it is clicked.

Thank you!

Code :

package UserInterface;
 
import BusinessModel.Controller;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.*;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
 
 
public class ProductPanel extends JPanel implements ActionListener, ListSelectionListener 
{
    private Controller ctrl = new Controller();
    private JButton btnInventory;
    private JButton btnAdd;
    private JButton btnReturn;
    private JList lstInventory;
    private JList lstCart;
    private JTextArea txtDetails;
    private JScrollPane scroll;
    private DefaultListModel model;
    private DefaultListModel modelCart;
    private JRadioButton black, blue, red;
 
    ProductPanel()
    {
 
        // Create Graphical Objects
        ButtonGroup buttonGroup = new ButtonGroup();
 
        black = new JRadioButton("Black");
        buttonGroup.add(black);
        black.setSelected(true);
 
        blue = new JRadioButton("Blue");
        buttonGroup.add(blue);
 
        red = new JRadioButton("Red");
        buttonGroup.add(red);
 
        btnInventory = new JButton ("Inventory");
        if(black.isSelected())
            btnInventory.setForeground(Color.BLACK);
        else if(blue.isSelected())
            btnInventory.setForeground(Color.BLUE);
        else if (red.isSelected())
            btnInventory.setForeground(Color.RED);
        btnInventory.setFont(new Font("Arial",Font.BOLD,14));
        btnInventory.setToolTipText("View Inventory");
 
        btnAdd = new JButton ("Add");
        if(black.isSelected())
            btnAdd.setForeground(Color.BLACK);
        else if(blue.isSelected())
            btnAdd.setForeground(Color.BLUE);
        else if(red.isSelected())
            btnAdd.setForeground(Color.RED);
        btnAdd.setFont(new Font("Arial",Font.BOLD,14));
        btnAdd.setToolTipText("Add item to cart");
 
        btnReturn = new JButton ("Return");
        if(black.isSelected())
            btnReturn.setForeground(Color.BLACK);
        else if(blue.isSelected())
            btnReturn.setForeground(Color.BLUE);
        else if(red.isSelected())
            btnReturn.setForeground(Color.RED);
        btnReturn.setFont(new Font("Arial",Font.BOLD,14));
        btnReturn.setToolTipText("Remove item from cart");
 
 
        // Product List
        model = new DefaultListModel();
        lstInventory = new JList(model);
        lstInventory.setPreferredSize(new Dimension(300,200));
        lstInventory.setBorder(BorderFactory.createLineBorder(Color.BLACK));
 
        // Display details
        txtDetails = new JTextArea(14,30);
        txtDetails.setFont(new Font("Arial",Font.PLAIN,12));
        txtDetails.setEditable(false);
        scroll = new JScrollPane(txtDetails);
        scroll.setBorder(BorderFactory.createLineBorder(Color.BLACK));
 
        // Labels
        JPanel cartL = new JPanel();
        JLabel cartLabel = new JLabel ("Cart");
        cartL.add(cartLabel = new JLabel("User's Cart"));
 
        JPanel colorL = new JPanel();
        JLabel colorLabel = new JLabel ("Color");
        colorL.add(colorLabel = new JLabel("Choose Font Color"));
 
 
        // Display Cart
        modelCart = new DefaultListModel();
        lstCart = new JList(modelCart);
        lstCart.setPreferredSize(new Dimension(495,200));
        lstCart.setBorder(BorderFactory.createLineBorder(Color.BLACK));
 
        // Register event listeners
        black.addActionListener(this);
        blue.addActionListener(this);
        red.addActionListener(this);
        btnInventory.addActionListener(this);
        btnAdd.addActionListener(this);
        btnReturn.addActionListener(this);
        lstInventory.addListSelectionListener(this);
        lstCart.addListSelectionListener(this);
 
 
        // Button Panel
        JPanel btnpanel = new JPanel();
        btnpanel.setLayout(new GridLayout(6,1));
        btnpanel.add(btnInventory);
        btnpanel.add(btnAdd);
        btnpanel.add(btnReturn);
        btnpanel.add(colorL);
        btnpanel.add(black);
        btnpanel.add(blue);
        btnpanel.add(red);
 
        // Add objects to panel
        add(btnpanel);
        add(lstInventory);
        add(scroll);
        add(cartL);
        add(lstCart);
 
    }
 
 
    public void actionPerformed(ActionEvent event) 
    {
        Object source = event.getSource();
 
        if(source == btnInventory)
        {
            model.clear();
            ArrayList  myList = ctrl.listContents();
            for (String s : myList)
            {
                model.addElement(s);
            }
        }
        else if (source == btnAdd)
        {
            if(lstInventory.isSelectionEmpty())
                JOptionPane.showMessageDialog(null, "No Product Selected!");
            else
            {
            String cartID = lstInventory.getSelectedValue().toString();
            String[] fields = cartID.split(",");
            ctrl.addToCart(fields[0]);
            modelCart.clear();
            ArrayList  myCart = ctrl.listCart();
            for (String s : myCart)
            {
             modelCart.addElement(s);
            }
            }
 
        }
        else if (source == btnReturn)
        {
            if(lstCart.isSelectionEmpty())
                JOptionPane.showMessageDialog(null, "No Product Selected!");
            else
            {
            String cartID = lstCart.getSelectedValue().toString();
            String[] fields = cartID.split(",");
            ctrl.removeFromCart(fields[0]);
            modelCart.clear();
            ArrayList  myCart = ctrl.listCart();
 
            for(String s : myCart)
            {
                modelCart.addElement(s);
            }
            }
        }
    }
 
    public void valueChanged(ListSelectionEvent e) 
    {
        //Read list and get product key
        String ID = lstInventory.getSelectedValue().toString();
        String[] fields = ID.split(",");
        txtDetails.setText(ctrl.getProductInfo(fields[0]));
    }
}

Several questions about my code

ProgrammerNoobE — Thu, 23 May 2013 20:03:53 GMT

Hello,

The comments in the code are my specified questions about the code. Please help me with finding the proper solution. I searched on the web, but I did not find the right solution for my problem. I couldn't find the right way to implement the information I found on the internet. So that's why I need some people who have more experience with Java who are willing to help me.

Could you help me please?

This is my code (with comments/questions):

Code Java:

 
import java.util.Scanner;
import java.util.ArrayList;
 
class Bank{
  double balance;
  //Account account;
  ArrayList<Account>account = new ArrayList<Account>();
  CommandReader commandReader;
 
  Bank(){
    commandReader = new CommandReader();
  }
 
  void run(){
    commandReader.run();  // The commandReader is a class which already should be fine
  }
 
  void enroll(String name){
    if(account.equals(account)){  //Why is this always true? I doesn't want to create two of the same accounts. In the commandReader the input is enroll Name
      System.out.println("already enrolled");
    } else {
      account.add(account); //This does also not work properly! when enroll Name is typed in by the user, there should be enrolled an account with name = Name and balance = 0
    }
  }
 
  void print(String name){
    if(account.equals(account)){
      System.out.println("Account of "+name);
      System.out.println("  balance: "+balance);
    } else {
      System.out.println("no such name "+name);
    }
  }
 
  void printAll(){
    if(account.equals(account)){
      System.out.println(account); //What I want to print here are all the accounts and they should be printed the same as the method above prints the accounts
    }
  }
 
  public static void main(String[] args){
      new Bank().run();
  }
}
 
class Account{
  double balance;
  String name;
 
  Account(){
    bank = new Bank(); //Is this necessary?
  }
 
  void user(String name, double balance){
    this.name = name;
    this.balance = balance;  //I think I don't understand it yet. The name and balance is what I want to store of the accounts
  }
}

What gives?

iansmiler — Thu, 23 May 2013 20:01:40 GMT

Hello, I am trying to get to grips with Java and specifically at this moment with text input, I wrote this with some help from Dr Google:

Code java:

package stringvars;
 
import java.util.Scanner;
 
public class StringVariables {
 
  public static void main(String[] args) {
 
  	  Scanner user_input = new Scanner(System.in);
 
  	  String first_name;
  	  System.out.print("Enter your first name: ");
  	  first_name = user_input.next();
 
  	  String family_name;
  	  System.out.print("Enter family name: ");
  	  family_name = user_input.next();
 
  	  String full_name;
  	  full_name = first_name + " " + family_name;
 
  	  System.out.println("You are " + full_name);
  }
}

It did not work�. So I tinkered with it and low and behold, when I removed the top line (package stringvars;) it worked ☺

So � my question is why?

Thanks in advance for any help � Ian ☺