chroot said:
gnome said:
gnome said:
Strange statement.
Checking the backtrace is usually a lot faster. You can only guess where the problems are happening, the backtrace tells you where.
They are done by professional programmers all the time. We are only humans.
The more complex code, the more complex datastructures etc. the more complex debugging becomes. Using a debugger with threaded code can tell you what thread is causing problems. I don't understand why this would be useless.
All programmers make mistakes. Few truly professional programmers make the same mistakes that students would make. The type of mistakes a programmer makes is certainly related to his/her experience. The effectiveness of a debugger is related to the type of errors being made, and thus is also related to the programmers experience.Dr-NiKoN said:
I never said that. I said that experienced programmers don't make the kind of mistakes that debuggers are good at exposing.
Once again, it's a matter of philosophy. Many experienced programmers, myself included, think quite poorly of overuse of a debugger.
What if the problem does not exist in one thread, but exists in the interdependence or cooperation of more than one thread?
You are welcome to your opinion. I have watched many students cling to the debugger far too long. Using a debugger forces a sort of "tunnel vision," in which students will make a change to their code, observe its behavior in the debugger, edit their code again, and so on. They freely add +1, for example, anytime they're off by one, without really considering the larger reason why their loop wasn't initialized properly in the first place. They place bandaids on open wounds without curing the underlying disease.
but I'd appreciate any constructive criticism you might offer.// MyQueue.java
public class MyQueue {
MyNode first;
MyNode last;
int size;
public MyQueue() {
first = null;
last = null;
size = 0;
}
public boolean isEmpty() {
if (size == 0)
return true;
else
return false;
}
public void enQueue(Object o) {
MyNode nextNode = new MyNode(o);
if (isEmpty()) {
first = nextNode;
last = nextNode;
}
else {
last.next = nextNode;
last = nextNode;
}
size++;
}
public Object deQueue() {
MyNode temp = first;
if (size == 1) {
first = null;
last = null;
size --;
}
else if (size > 1) {
first = first.next;
size --;
}
return temp.data;
}
public void Empty() {
first = last = null;
size = 0;
}
}
class MyNode {
Object data;
MyNode next;
MyNode (Object o) {
data = o;
next = null;
}
}// testMyQueue.java
// test driver for MyQueue class
class testMyQueue {
public static void main(String[] args) {
MyQueue q = new MyQueue();
Integer n;
for(int j=0; j<4; j++) {
System.out.println("\nTesting five entries to the queue.");
for(int i=0; i<5; i++) {
n = new Integer(2*i*j);
q.enQueue(n);
}
while(!q.isEmpty()){
n = (Integer) q.deQueue();
System.out.println(n);
}
}
q.Empty();
if(q.isEmpty()) {
System.out.println("The queue is now empty.\n");
System.out.println("One last trial...");
}
for(int i=0; i<5; i++) {
n = new Integer(10*i);
q.enQueue(n);
}
while(!q.isEmpty()){
n = (Integer) q.deQueue();
System.out.println(n);
}
System.out.println("Goodbye.");
}
}gnome said:Here's my first stab at Java. No fancy graphics, just a simple queue implemented as a linked list. It actually seems to work
super();public class MyQueue {
private class MyNode {
Object data;
MyNode next;
MyNode () { // constructor for sentinel node
data = null;
next = null;
}
MyNode (Object o) { // constructor for other nodes
data = o;
next = null;
}
};
private MyNode sentinel, last;
public MyQueue() {
last = sentinel = new MyNode();
}
public boolean isEmpty() {
return sentinel == last;
}
public void enQueue(Object o) {
MyNode nextNode = new MyNode(o);
last.next = nextNode;
last = nextNode;
}
public Object deQueue() throws EmptyQueueException {
if (last == sentinel)
throw new EmptyQueueException();
MyNode temp = sentinel.next;
sentinel.next = temp.next;
if (last == temp)
last = sentinel;
return temp.data;
}
public void empty() {
last = sentinel;
last.next = null;
}
}public class EmptyQueueException extends java.lang.Exception {
EmptyQueueException() {
super();
}
EmptyQueueException(String s) {
super(s);
}
}class testMyQueue {
public static void main(String[] args) {
MyQueue q = new MyQueue();
Integer n;
for(int j=0; j<4; j++) {
System.out.println("\nTesting five entries to the queue.");
for(int i=0; i<5; i++) {
n = new Integer(2*i*j);
q.enQueue(n);
}
while(true){
try {
n = (Integer) q.deQueue();
System.out.println(n);
} catch (EmptyQueueException e) {
System.out.println("Queue is empty");
break;
}
}
}
for(int i=0; i<5; i++) {
n = new Integer(2*i);
q.enQueue(n);
}
q.empty();
if(q.isEmpty()) {
System.out.println("The queue is now empty.\n");
System.out.println("One last trial...");
}
for(int i=0; i<5; i++) {
n = new Integer(10*i);
q.enQueue(n);
}
while(!q.isEmpty()){
try {
n = (Integer) q.deQueue();
System.out.println(n);
} catch (EmptyQueueException e) {
System.out.println("We should never get caught here.");
}
}
System.out.println("Goodbye.");
}
}gnome said:
public Object deQueue() throws EmptyQueueException {
if (last == sentinel)
throw new EmptyQueueException();
MyNode temp = sentinel.next;
sentinel.next = temp.next;
if (last == temp)
last = sentinel;
return temp.data;
}Thanks again. Actually, if I make that change, I can also eliminate the line (sentinel.next = temp.next;) above that second if so now deQueue is just:
public Object deQueue() throws EmptyQueueException {
if (last == sentinel)
throw new EmptyQueueException();
MyNode temp = sentinel.next;
sentinel = temp;
return temp.data;
}// Complex.java
// implements a complex number type
public class Complex {
public Complex() {
_real = 0.0;
_imag = 0.0;
}
public Complex (double re, double im) {
_real = re;
_imag = im;
}
public static Complex add (Complex x, Complex y) {
return new Complex(x._real + y._real, x._imag + y._imag);
}
public static Complex subt (Complex x, Complex y) {
return new Complex(x._real - y._real, x._imag - y._imag);
}
public static Complex mult (Complex x, Complex y) {
return new Complex(x._real * y._real, x._imag * y._imag);
}
static public Complex div (Complex x, Complex y) {
return new Complex(x._real / y._real, x._imag / y._imag);
}
public static double real(Complex x) {
return x._real;
}
public static double imag(Complex x) {
return x._imag;
}
public double real () {
return _real;
}
public double imag () {
return _imag;
}
private double _real, _imag;
}// TestComplex.java
// test driver for Complex class
class TestComplex {
public static void main (String[] args) {
double re,im;
Complex c1, c2, c3, result;
c1 = new Complex();
c2 = new Complex();
c3 = new Complex();
System.out.println("Testing default constructor with instance methods:");
System.out.println("c1 = " + c1.real() + " + " + c1.imag() + "i");
System.out.println("Testing default constructor with static methods:");
System.out.println("c1 = " + Complex.real(c1) + " + " + Complex.imag(c1) + "i");
System.out.println("Testing set-value constructor:");
c1 = new Complex(6.4,5.6);
c2 = new Complex(2.0,2.8);
System.out.println("c1 = " + c1.real() + " + " + c1.imag() + "i");
System.out.println("c2 = " + c2.real() + " + " + c2.imag() + "i");
System.out.println("\nTesting addition:");
result = Complex.add(c1,c2);
System.out.print("(" + c1.real() + " + " + c1.imag() + "i)");
System.out.print(" + (" + c2.real() + " + " + c2.imag() + "i)");
System.out.println(" = (" + result.real() + " + " + result.imag() + "i)");
System.out.println("\nTesting subtraction:");
result = Complex.subt(c1,c2);
System.out.print("(" +c1.real() + " + " + c1.imag() + "i)");
System.out.print(" - (" + c2.real() + " + " + c2.imag() + "i)");
System.out.println(" = (" + result.real() + " + " + result.imag() + "i)");
System.out.println("\nTesting multiplication:");
result = Complex.mult(c1,c2);
System.out.print("(" +c1.real() + " + " + c1.imag() + "i)");
System.out.print(" * (" + c2.real() + " + " + c2.imag() + "i)");
System.out.println(" = (" + result.real() + " + " + result.imag() + "i)");
System.out.println("\nTesting division:");
result = Complex.div(c1,c2);
System.out.print("(" +c1.real() + " + " + c1.imag() + "i)");
System.out.print(" / (" + c2.real() + " + " + c2.imag() + "i)");
System.out.println(" = (" + result.real() + " + " + result.imag() + "i)");
System.out.println("\nTesting division by zero:");
result = Complex.div(c1,c3);
System.out.print("(" +c1.real() + " + " + c1.imag() + "i)");
System.out.print(" / (" + c2.real() + " + " + c2.imag() + "i)");
System.out.println(" = (" + result.real() + " + " + result.imag() + "i)");
System.out.println("\nFinished.");
}
}NumberFormat numberFormatter = new NumberFormat();
numberFormatter.setMaximumFractionDigits(2);
System.out.println(...numberFormatter.format(c1.real())...);