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How can I avoid java.lang.ArrayIndexOutOfBoundsException when joining a Queue?

I'm working on a simple(?) exercise for my Data Structures class. It works fine right up until I have an element leave the queue then try to add another one on at which point I get the following error:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 10 out of bounds for length 10
at queueExercise.IntegerQueue.join(IntegerQueue.java:20)
at queueExercise.IntegerQueueTest.main(IntegerQueueTest.java:27)
My code is as follows:
Queue Constructor Class:
public class IntegerQueue {
private int[] queue;
private int front;
private int end;
private int noInQueue;
private int count;
private boolean full;
public IntegerQueue(int max) {
queue = new int[max];
front = end = 0;
full = false;
}
public void join(int newValue) {
if (isFull()==false) {
queue[end] = newValue;
count++;
if (end == queue.length) {
end = 0;
}
else {
end++;
}
}else
System.out.println("Error: Queue Full");
}
public int leave() {
if (isEmpty()==false) {
noInQueue = queue[front];
queue[front]=0;
front++;
if (front==queue.length) {
front = 0;
}
count--;
}
else {
System.out.println("Error: Queue Empty");
}
System.out.println("Leaving: "+noInQueue);
return noInQueue;
}
public boolean isEmpty() {
if (count == 0){
return true;
}
else
return false;
}
public boolean isFull() {
if (count >= queue.length) {
return true;
}
else
return false;
}
public void printQueue() {
if (!isEmpty()) {
System.out.println("Printing Queue");
int pos = front;
int i =0;
while(i<queue.length) {
System.out.println(queue[pos]);
pos++;
i++;
if (pos >=queue.length) {
pos = 0;
}
}
}
}
}
Test Class
public class IntegerQueueTest {
static IntegerQueue q = new IntegerQueue(10);
public static void main(String[] args) {
int j;
System.out.println("Creating Queue");
for (int i = 0; i <10; i++) {
j = (int)(Math.random()*100);
if (!q.isFull()) {
q.join(j);
System.out.println("Adding: "+j);
}
}
q.printQueue();
q.join(112);
q.leave();
q.leave();
q.leave();
q.printQueue();
q.join(112);
q.join(254);
q.printQueue();
}
}

The problem is in the join method and more precisely in the condition if (end == queue.length). All you have to do is change it to if (end == queue.length - 1).

Java Maze Solver - Stack does not pop when pop() is called

I'm working on an assignment where I have to solve a maze through backtracking (using a stack!) and the logic of the code is basically done, but the main problem is whenever I call pop() on my stack, it does not pop.So for now I have manually added (hardcoded) the parts in the maze where it is supposed to pop(). I am using my own stack that is using Linked Nodes and have ran JUnit and Main tests and it does indeed work (doubting myself here now). I have also used the Java stack and I get the same result.
Here is my code logic: As you can see in the method mazeSolver, at the bottom, I have a few if statements that check if i (operations performed) is at a certain point and it will "backtrack", but I am manually setting the position. The very last else statement is the part where I pop(). Any help would very much be appreciated.
public class MazeSolver {
private char[][] printMaze;
private char[][] solveMaze;
public MazeSolver() {
super();
}
private class Position {
private int x;
private int y;
Position(int y, int x) {
this.x = x;
this.y = y;
}
public int getX() {
return this.x;
}
public int getY() {
return this.y;
}
public void setX(int x) {
this.x = x;
}
public void setY(int y) {
this.y = y;
}
}
public boolean solve(boolean printUpdates) {
char space = ' ';
Stack<Position> stack = new Stack<Position>();
//Stack stack = new Stack();
Position cp = new Position(1, 0);
boolean done = true;
char c = 'C';
char x = 'X';
int i = 0;
while (done) {
// check right
if (printMaze[cp.getY()][cp.getX() + 1] == space && printMaze[cp.getY()][cp.getX() + 1] != x) {
cp.setX(cp.getX() + 1);
stack.push(cp);
printMaze[cp.getY()][cp.getX()] = 'C';
}
// check bottom
else if (printMaze[cp.getY() + 1][cp.getX()] == space && printMaze[cp.getY() + 1][cp.getX()] != x
&& printMaze[cp.getY() + 1][cp.getX()] != x) {
cp.setY(cp.getY() + 1);
stack.push(cp);
printMaze[cp.getY()][cp.getX()] = 'C';
}
// check top
else if (printMaze[cp.getY() - 1][cp.getX()] == space && printMaze[cp.getY() - 1][cp.getX()] != x) {
cp.setY(cp.getY() - 1);
stack.push(cp);
printMaze[cp.getY()][cp.getX()] = 'C';
}
// check left
else if (printMaze[cp.getY()][cp.getX() - 1] == space && printMaze[cp.getY()][cp.getX() - 1] != x) {
cp.setX(cp.getX() - 1);
stack.push(cp);
printMaze[cp.getY()][cp.getX()] = 'C';
}
//else {
/*
if (i == 6) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(1);
cp.setX(5);
} else if (i == 27) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(1);
cp.setX(20);
}
else if (i == 37) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(2);
cp.setX(18);
}
else if (i == 68) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(13);
cp.setX(22);
} else if (i == 69) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(14);
cp.setX(22);
}
else if (i == 70) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(15);
cp.setX(22);
} else if (i == 71) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(16);
cp.setX(22);
} else if (i == 72) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(17);
cp.setX(22);
} else if (i == 103) {
printMaze[cp.getY()][cp.getX()] = 'X';
cp.setY(21);
cp.setX(31);
} */else {
printMaze[cp.getY()][cp.getX()] = 'X';
stack.pop();
cp.setY(((Position) stack.top()).getY());
cp.setX(((Position) stack.top()).getX());
}
//}
i++;
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
// System.out.println(stack.top().getX() + ", " + stack.top().getY());
System.out.println(cp.getY() + ", " + cp.getX() + " i = " + i);
printMaze();
}
System.out.println("success");
return false;
}
public void printMaze() {
for (int i = 0; i < printMaze.length; i++) {
for (int j = 0; j < printMaze[i].length; j++) {
System.out.print(printMaze[i][j]);
}
System.out.println("");
}
}
public boolean loadMaze(String filename) {
BufferedReader br = null;
FileReader fr = null;
ArrayList<String> lines = new ArrayList<String>();
try {
fr = new FileReader(filename);
br = new BufferedReader(fr);
String line;
br = new BufferedReader(new FileReader(filename));
while ((line = br.readLine()) != null) {
lines.add(line);
}
printMaze = new char[lines.size()][];
solveMaze = new char[lines.size()][];
for (int i = 0; i < lines.size(); i++) {
printMaze[i] = new char[lines.get(i).length()];
solveMaze[i] = new char[lines.get(i).length()];
for (int j = 0; j < lines.get(i).length(); j++) {
solveMaze[i][j] = lines.get(i).charAt(j);
printMaze[i][j] = lines.get(i).charAt(j);
if (solveMaze[i][j] == 'S') {
// hint you need to do this but you do not have the
// instance variable yet
// start = new Position(i, j);
}
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null)
br.close();
if (fr != null)
fr.close();
} catch (IOException ex) {
return false;
}
}
return true;
}
Here is my stack implementation if interested.
public class Stack<Item> implements StackInterface<Item> {
private int size;
private class Link {
private Item data;
public Link next;
public Link(Item data, Link next) {
this.data = data;
this.next = next;
}
public Item getData() {
return data;
}
}
private Link topStackLink = null;
public Stack() {
this.size = 0;
}
#Override
public void push(Item item) {
if (topStackLink == null) {
topStackLink = new Link(item, null);
} else {
topStackLink = new Link(item, topStackLink);
}
this.size++;
}
#Override
public void pop() {
// TODO Auto-generated method stub
if (topStackLink != null) {
topStackLink = topStackLink.next;
this.size--;
} else {
throw new java.util.EmptyStackException();
}
}
#Override
public Item top() {
if (topStackLink != null) {
return topStackLink.data;
} else {
throw new java.util.EmptyStackException();
}
}
#Override
public Item topAndPop() {
// TODO Auto-generated method stub
if (topStackLink != null) {
Item item = topStackLink.data;
pop();
return item;
} else {
throw new java.util.EmptyStackException();
}
}
#Override
public boolean isEmpty() {
if (topStackLink == null) {
return true;
} else {
return false;
}
}
#Override
public void makeEmpty() {
// TODO Auto-generated method stub
topStackLink = null;
this.size = 0;
}
#Override
public int size() {
return this.size;
}

AVL tree in java

The program that I am writing simulates a road charging system which reads several lines of inputs, each one representing a different command until I reach the EOF (\n).
This commands simulate a road charging system, where the input reads as follows:
PASS 44AB55 I -> where the first word is the command the program receives, the second word is the number plate of the car (44AB55) and the second is the status of the car (Regular or Irregular).
There are three types of commands:
“PASS 00AA00 R” – Increments the number of times that the car has passed in the system and marks its status has Regular or Irreguar. If the car isnt still in the database, it inserts the car as Regular and starts the counter with one passage.
“UNFLAG 00AA00” – Flags the car as Regular if it exists in the database. If the car doesnt exist in the database ignores the command.
“STATUS 00AA00” – Retrieves the status of the car (Regular or Irregular) and the number of passages of the car in the system. If it the car doesnt exist in the database, prints a "NO RECORD" message.
To solve this problem, I am using AVL trees and using the following code:
import java.util.ArrayList;
import java.util.Scanner;
public class TP2_probB {
static No raiz = null;
static double numRotacoes = 0;
static double numAtravessos = 0;
public static class No {
private String matricula;
private int porticos;
private boolean estadoRegular;
private No pai;
private No filhoEsq;
private No filhoDir;
private int balanco;
public No(String matricula, int porticos, boolean estadoRegular) {
this.matricula = matricula;
this.porticos = porticos;
this.estadoRegular = estadoRegular;
this.pai = null;
this.filhoDir = null;
this.filhoEsq = null;
this.balanco = 0;
}
public void setEstadoRegular(boolean estadoRegular) {
this.estadoRegular = estadoRegular;
}
public void setPai(No pai) {
this.pai = pai;
}
public void setFilhoEsq(No filhoEsq) {
this.filhoEsq = filhoEsq;
}
public void setFilhoDir(No filhoDir) {
this.filhoDir = filhoDir;
}
public void atribuiNoEsq(No noEsq) {
this.filhoEsq = noEsq;
}
public void atribuiNoDir(No noDir) {
this.filhoDir = noDir;
}
public void atribuiPai(No noPai) {
this.pai = noPai;
}
public void aumentaPortico() {
porticos++;
}
public String getMatricula() {
return matricula;
}
public boolean isEstadoRegular() {
return estadoRegular;
}
public No getPai() {
return pai;
}
public No getFilhoEsq() {
return filhoEsq;
}
public No getFilhoDir() {
return filhoDir;
}
#Override
public String toString() {
String estado;
if (estadoRegular == true) {
estado = "R";
} else {
estado = "I";
}
return matricula + " " + porticos + " " + estado;
}
}
public static No duplaRotacaoFilhoEsq(No k3)
{
k3.filhoEsq = rotacaoFilhoDir(k3);
return rotacaoFilhoEsq(k3);
}
public static No duplaRotacaoFilhoDir(No k3)
{
k3.filhoDir = rotacaoFilhoEsq(k3);
return rotacaoFilhoDir(k3);
}
public static No rotacaoFilhoDir(No k1) {
No k2 = k1.filhoDir;
k2.pai=k1.pai;
k1.filhoDir = k2.filhoEsq;
if(k1.filhoDir!=null)
{
k1.filhoDir.pai=k1;
}
k2.filhoEsq = k1;
k1.pai=k2;
if(k2.pai!=null)
{
if(k2.pai.filhoDir==k1)
{
k2.pai.filhoDir = k2;
}
else if(k2.pai.filhoEsq==k1)
{
k2.pai.filhoEsq = k2;
}
}
balanco(k2);
balanco(k1);
return k2;
}
public static No rotacaoFilhoEsq(No k1) {
No k2 = k1.filhoEsq;
k2.pai=k1.pai;
k1.filhoEsq = k2.filhoDir;
if(k1.filhoEsq!=null)
{
k1.filhoEsq.pai=k1;
}
k2.filhoDir = k1;
k1.pai=k2;
if(k2.pai!=null)
{
if(k2.pai.filhoDir==k1)
{
k2.pai.filhoDir = k2;
}
else if(k2.pai.filhoEsq==k1)
{
k2.pai.filhoEsq = k2;
}
}
balanco(k2);
balanco(k1);
return k2;
}
public static int pesagem(No aux)
{
if(aux==null)
{
return -1;
}
if(aux.filhoEsq == null && aux.filhoDir == null)
{
return 0;
}
else if ((aux.filhoEsq == null))
{
return (pesagem(aux.filhoDir) + 1);
}
else if ((aux.filhoDir == null))
{
return (pesagem(aux.filhoEsq) + 1);
}
else
return (Math.max(pesagem(aux.filhoEsq), pesagem(aux.filhoDir)) + 1);
}
public static void balanco(No tmp)
{
tmp.balanco = pesagem(tmp.filhoDir)-pesagem(tmp.filhoEsq);
}
public static void main(String args[]) {
Scanner input = new Scanner(System.in);
String linha;
String[] aux;
ArrayList<String> output = new ArrayList<String>();
int x = 0;
while (true) {
linha = input.nextLine();
if (linha.isEmpty())
{
break;
}
else
{
aux = linha.split(" ");
if (aux[0].compareTo("PASS") == 0) {
No novo;
if (aux[2].compareTo("R") == 0) {
novo = new No(aux[1], 1, true);
} else {
novo = new No(aux[1], 1, false);
}
if (raiz == null) {
raiz = novo;
balanco(raiz);
} else {
procuraNo(novo);
}
} else if (aux[0].compareTo("UNFLAG") == 0) {
if (raiz != null) {
No no = new No(aux[1], 0, false);
mudaEstado(no);
}
} else if (aux[0].compareTo("STATUS") == 0) {
if (raiz == null) {
output.add(aux[1] + " NO RECORD");
} else {
No no = new No(aux[1], 0, false);
output.add(procuraRegisto(no));
}
}
}
}
for (int i = 0; i < output.size(); i++) {
System.out.println(output.get(i));
}
System.out.println("Número de Rotações: "+numRotacoes+"\nNúmero de atravessias: "+numAtravessos);
}
public static void procuraNo(No novo) {
No aux = raiz;
while (true) {
if (aux.getMatricula().compareTo(novo.getMatricula()) == 0) {
aux.aumentaPortico();
aux.setEstadoRegular(novo.isEstadoRegular());
equilibra(aux);
break;
} else if (aux.getMatricula().compareTo(novo.getMatricula()) < 0) {
if (aux.getFilhoDir() == null) {
novo.setPai(aux);
aux.setFilhoDir(novo);
aux=aux.filhoDir;
equilibra(aux);
break;
} else {
aux = aux.getFilhoDir();
numAtravessos++;
}
} else if (aux.getMatricula().compareTo(novo.getMatricula()) > 0) {
if (aux.getFilhoEsq() == null) {
novo.setPai(aux);
aux.setFilhoEsq(novo);
aux=aux.filhoEsq;
equilibra(aux);
break;
} else {
aux = aux.getFilhoEsq();
numAtravessos++;
}
}
}
}
public static void equilibra(No tmp) {
balanco(tmp);
int balanco = tmp.balanco;
System.out.println(balanco);
if(balanco==-2)
{
if(pesagem(tmp.filhoEsq.filhoEsq)>=pesagem(tmp.filhoEsq.filhoDir))
{
tmp = rotacaoFilhoEsq(tmp);
numRotacoes++;
System.out.println("Rodou");
}
else
{
tmp = duplaRotacaoFilhoDir(tmp);
numRotacoes++;
System.out.println("Rodou");
}
}
else if(balanco==2)
{
if(pesagem(tmp.filhoDir.filhoDir)>=pesagem(tmp.filhoDir.filhoEsq))
{
tmp = rotacaoFilhoDir(tmp);
numRotacoes++;
System.out.println("Rodou");
}
else
{
tmp = duplaRotacaoFilhoEsq(tmp);
numRotacoes++;
System.out.println("Rodou");
}
}
if(tmp.pai!=null)
{
equilibra(tmp.pai);
}
else
{
raiz = tmp;
}
}
public static void mudaEstado(No novo) {
No aux = raiz;
while (true) {
if (aux.getMatricula().compareTo(novo.getMatricula()) == 0) {
aux.setEstadoRegular(true);
break;
} else if (aux.getMatricula().compareTo(novo.getMatricula()) < 0) {
if (aux.getFilhoDir() == null) {
break;
} else {
aux = aux.getFilhoDir();
numAtravessos++;
}
} else if (aux.getMatricula().compareTo(novo.getMatricula()) > 0) {
if (aux.getFilhoEsq() == null) {
break;
} else {
aux = aux.getFilhoEsq();
numAtravessos++;
}
}
}
}
public static String procuraRegisto(No novo) {
No aux = raiz;
while (true) {
if (aux.getMatricula().compareTo(novo.getMatricula()) == 0) {
return aux.toString();
} else if (aux.getMatricula().compareTo(novo.getMatricula()) < 0) {
if (aux.getFilhoDir() == null) {
return (novo.getMatricula() + " NO RECORD");
} else {
aux = aux.getFilhoDir();
numAtravessos++;
}
} else if (aux.getMatricula().compareTo(novo.getMatricula()) > 0) {
if (aux.getFilhoEsq() == null) {
return (novo.getMatricula() + " NO RECORD");
} else {
aux = aux.getFilhoEsq();
numAtravessos++;
}
}
}
}
}
The problem is that I am getting a stack overflow error:
Exception in thread "main" java.lang.StackOverflowError
at TP2_probB.pesagem(TP2_probB.java:174)
at TP2_probB.pesagem(TP2_probB.java:177)
at TP2_probB.pesagem(TP2_probB.java:177)
at TP2_probB.pesagem(TP2_probB.java:177)
(...)
at TP2_probB.pesagem(TP2_probB.java:177)
Here is a link with two files with inputs used to test the program:
https://drive.google.com/folderview?id=0B3OUu_zQ9xlGfjZHRlp6QkRkREc3dU82QmpSSWNMRlBuTUJmWTN5Ny1LaDhDN3M2WkVjYVk&usp=sharing

How to check diagonals in NQueens?

Im making the NQueens program in java but I am having trouble checking the diagonals. Right now I just go through the array in a way so it goes to the next diagonal spot but it is giving me out of bounds after going through the first possibility. Is there a different way to do this? Am i doing it wrong?
Here is the part that is giving me the array out of bounds exception
private boolean checkLowerDiag(int row, int col)
{
if(col == 0)
{
return false;
}
else
{
for(int i = row, j = col; i < myNumsQueen && j >= 0; i++, j--)
{
if(myBoard[i+1][j-1] == true) // this line is the out of bounds
{
return true;
}
}
return false;
}
}
Here is my entire code
package model;
public class NQueensModel
{
private int myNumsQueen;
public int myPossibilities=0;
private boolean[][] myBoard;
private static NQueensModel myModel = new NQueensModel(4);
public static void main (String[] args) {
System.out.println(myModel.solvePuzzle());
System.out.println(myModel.myPossibilities);
// System.out.println(myPossibilities);
}
public NQueensModel(int nQueens)
{
myNumsQueen = nQueens;
myPossibilities=0;
myBoard = new boolean[myNumsQueen][myNumsQueen];
}
public boolean solvePuzzle()
{
return this.solvePuzzle(0);
}
private boolean solvePuzzle(int ncolumn)
{
if(ncolumn>myNumsQueen-1)
{
myPossibilities++;
// return true;
}
int i;
for( i =0; i<myNumsQueen;i++)
{
if(this.isSafeMove(i, ncolumn)==true)
{
this.placeQueen(i,ncolumn);
System.out.println(i+ " " + ncolumn);
if(this.solvePuzzle(ncolumn+1)==true)
{
return true;
}
this.removeQueen(i, ncolumn);
System.out.println("remove: " + i+ " " + ncolumn);
}
}
return false;
}
private int solveCount(int count, int col)
{
for(int j = 0 ; j<col; j++){
if(myModel.solvePuzzle(j)==true){
count++;
}
else if(myModel.solvePuzzle(j)==false){
return count;
}
else
{
for(int i =0 ; i<col;i++){
count = solveCount(count, col+1);
}
return count;
}
return count;
}
return count;
}
private boolean isSafeMove(int row, int col)
{
if(this.checkLowerDiag(row, col)==true ||this.checkUpperDiag(row, col)==true ||this.checkLeft(row,col)==true)
{
return false;
}
else
{
return true;
}
}
private boolean checkUpperDiag(int row, int col)
{
if(row==0)
{
return false;
}
else
{
for(int i=row, j = col; i>=0 && j>=0; i--, j--)
{
if(myBoard[i][j]==true)
{
return true;
}
}
return false;
}
}
private boolean checkLowerDiag(int row, int col)
{
if(col==0 )
{
return false;
}
else
{
for(int i = row, j = col; i<myNumsQueen && j>=0; i++, j--)
{
if(myBoard[i+1][j-1]==true)
{
return true;
}
}
return false;
}
}
private boolean checkLeft(int row, int col)
{
if(col==0)
{
return false;
}
else
{
for(int i = col; i>=0; i--)
{
if(myBoard[row][i]==true)
{
return true;
}
}
return false;
}
}
private boolean placeQueen(int row, int col)
{
myBoard[row][col] = true;
return true;
}
private boolean removeQueen(int row, int col)
{
myBoard[row][col] = false;
return false;
}
// public String toString()
// {
//
// }
}

GXT Paging Grid service method

In GXT is an example:
http://www.sencha.com/examples/#ExamplePlace:paginggrid
Where I can see realization of this method:
service.getPosts(loadConfig, callback);
or any other similar service

For example, here -
http://spring-rapid.googlecode.com/svn/trunk/atom-explorer/src/main/java/com/atom/ebank/wfront/examples/resources/server/ExampleServiceImpl.java
...
#Override
public PagingLoadResult<Post> getPosts(PagingLoadConfig config) {
if (posts == null) {
loadPosts();
}
if (config.getSortInfo().size() > 0) {
SortInfo sort = config.getSortInfo().get(0);
if (sort.getSortField() != null) {
final String sortField = sort.getSortField();
if (sortField != null) {
Collections.sort(posts, sort.getSortDir().comparator(new Comparator<Post>() {
public int compare(Post p1, Post p2) {
if (sortField.equals("forum")) {
return p1.getForum().compareTo(p2.getForum());
} else if (sortField.equals("username")) {
return p1.getUsername().compareTo(p2.getUsername());
} else if (sortField.equals("subject")) {
return p1.getSubject().compareTo(p2.getSubject());
} else if (sortField.equals("date")) {
return p1.getDate().compareTo(p2.getDate());
}
return 0;
}
}));
}
}
}
ArrayList<Post> sublist = new ArrayList<Post>();
int start = config.getOffset();
int limit = posts.size();
if (config.getLimit() > 0) {
limit = Math.min(start + config.getLimit(), limit);
}
for (int i = config.getOffset(); i < limit; i++) {
sublist.add(posts.get(i));
}
return new PagingLoadResultBean<Post>(sublist, posts.size(), config.getOffset());
}
...