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Reading from input, storing to output

Hello again,

I did some testing with this code, and found it did not work if the integers on my input.txt were separated by tabs instead of spaces. Is there a way I can have the output print the same format as the input?

Example:

input: 1 <tab> 2 <tab> <tab> 3
output: 1 <tab> 2 <tab> <tab> 3

input: 1 _ 2 _ _ 3
output: 1 _ 2 _ _ 3

Note: <tab> represents tab spaces, and "_" represents regular spaces.

ASKER

import java.io.*;
import java.util.*;

public class ReadInputArray {

public static void main (String[] arg) throws Exception {
// Read input array

BufferedReader readFile = new BufferedReader(new InputStreamReader(new FileInputStream("input.txt")));
String input = "";

File output = new File("output.txt"); // writes to output.txt
FileOutputStream outFromFile = new FileOutputStream(output);
PrintStream ps = new PrintStream(outFromFile);

try {

while((input = readFile.readLine())!=null) { // reads until there are no characters left

ArrayList resultList = new ArrayList(); // create new ArrayList for result
ArrayList digitsList = new ArrayList(); // create new ArrayList for ints

int len = input.length(); // length of input
StringBuffer sbDigits = new StringBuffer(); // create new string

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
char c = input.charAt(i);
if(c == ' ') { // if the character is a space
resultList.add("_" + c);
if(sbDigits.length()>0) { // join the two together
digitsList.add(new Integer(sbDigits.toString()));
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if
} // END if
else {
sbDigits.append(c);
} // END else
} // END for

if(sbDigits.length()>0){
digitsList.add(new Integer(sbDigits.toString()));
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if

for(int i=1; i<resultList.size(); i++){
//System.out.print(resultList.get(i));
ps.print(resultList.get(i)); // writes what was read to outout.txt
} // END for
} // END while
System.out.println("Process complete. Please check your output.txt.\n");
} // END try

catch(NumberFormatException notInt) {
System.out.println("Input not in correct format. Integers only please.");
System.out.println("Program will now exit.\n");
} // END catch
} // END main()

} // END class ReadInputArray

ASKER

After more testing, I found that these lines:

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
...
} // END for

if(sbDigits.length()>0){
digitsList.add(new Integer(sbDigits.toString()));
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if

miss the last space from the input.txt file.

Example:

input: 1 _ 2 _ _ 3
output: 1 _ 2 _ 3

Perhaps instead of a StringBuffer(), I should use StringTokenizer()??

ASKER

And what would happen if my input.txt had a combination of tabs and spaces separating the integers?

Example: input: 1 _ 2 _ <tab> 3

SOLUTION

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ASKER

Ok, that fixed the tab problem. Thank you!

But, it's still not counting the last space/tab.

ASKER

Hmm... it's also adding a space before the tab.

Example:

input: 1 <tab> 2 <tab> <tab> 3
output: 1 _ <tab> 2 _ <tab> 3 <------ still missing last tab

ASKER

Oh, nevermind about the space before the tab. I fixed it :)

So do you still have any problems with it?

ASKER

Well, it's still not reading the last space/tab. I got rid of the other problem (space before the tab).

Example:

input: 1 _ 2 _ _ 3
output: 1 _ 2 _ 3 <----- what happened to the last space??

can u post the current code

ASKER

import java.io.*;
import java.util.*;

public class ReadInputArray {

public static void main (String[] arg) throws Exception {
// Read input array

BufferedReader readFile = new BufferedReader(new InputStreamReader(new FileInputStream("input.txt")));
String input = "";

File output = new File("output.txt"); // writes to output.txt
FileOutputStream outFromFile = new FileOutputStream(output);
PrintStream ps = new PrintStream(outFromFile);

try {

while((input = readFile.readLine())!=null) { // reads until there are no characters left

ArrayList resultList = new ArrayList(); // create new ArrayList for result
ArrayList digitsList = new ArrayList(); // create new ArrayList for ints

int len = input.length(); // length of input
StringBuffer sbDigits = new StringBuffer(); // create new string

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
char c = input.charAt(i);
if(c == ' ' || c == '\t') { // if the character is a space or tab
resultList.add("" + c);
if(sbDigits.length()>0) { // join the two together
digitsList.add(new Integer(sbDigits.toString()));
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if
} // END if
else {
sbDigits.append(c);
} // END else
} // END for

if(sbDigits.length()>0){
digitsList.add(new Integer(sbDigits.toString()));
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if

for(int i=1; i<resultList.size(); i++){
ps.print(resultList.get(i)); // writes what was read to outout.txt
} // END for
} // END while
System.out.println("Process complete. Please check your output.txt.\n");
} // END try

catch(NumberFormatException notInt) {
System.out.println("Input not in correct format. Integers only please.");
System.out.println("Program will now exit.\n");
} // END catch

} // END main()

} // END class ReadInputArray

ASKER CERTIFIED SOLUTION

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ASKER

Hmm... it doesn't print the first integer.

And this

for(int i=0; i<resultList.size(); i++){ //<---------- i=1 should be i=0
System.out.println(">>"+resultList.get(i));
ps.print(resultList.get(i)); // writes what was read to outout.txt
} // END for

> Hmm... it doesn't print the first integer.

It was printing it before wasn't it?

ASKER

:) thank you gnoon!!

Okay, I have another question. Suppose I want to sort the integers using this quicksort code:

import java.util.Vector;

public class QuickSort
{
// Sorts entire array
public static void sort(Vector array)
{
sort(array, 0, array.size() - 1);
}

// Sorts partial array
public static void sort(Vector array, int start, int end)
{
int p;
if (end > start)
{
p = partition(array, start, end);
sort(array, start, p-1);
sort(array, p+1, end);
}
}

protected static int compare(Sortable a, Sortable b)
{
return a.compare(b);
}

protected static int partition(Vector array, int start, int end)
{
int left, right;
Sortable partitionElement;

// Arbitrary partition start...there are better ways...
partitionElement = (Sortable)array.elementAt(end);

left = start - 1;
right = end;
for (;;)
{
while (compare(partitionElement, (Sortable)array.elementAt(++left)) == 1)
{
if (left == end) break;
}
while (compare(partitionElement, (Sortable)array.elementAt(--right)) == -1)
{
if (right == start) break;
}
if (left >= right) break;
swap(array, left, right);
}
swap(array, left, end);

return left;
}

protected static void swap(Vector array, int i, int j)
{
Object temp;

temp = array.elementAt(i);
array.setElementAt(array.elementAt(j), i);
array.setElementAt(temp, j);
}
}

How would I call on it from the main method?

ASKER

or is there a better code for the quicksort? That's the one I learned...

You'll need to either change your QuickSort class to use List instead of Vector, or change your resultList to be a Vector (I'd suggest the former)

Then to call it use:

QuickSort.sort(resultList);

> or is there a better code for the quicksort?

Collections.sort(resultList);

ASKER

So, for these:

public static void sort(Vector array) {
...
public static void sort(Vector array, int start, int end)...

change it to

public static void sort(List array) {
...
public static void sort(List array, int start, int end)...

ASKER

Uh oh! Comes up with a bunch of errors. I think because the code was dependent on the Vector thing:

C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:20: cannot resolve symbol
symbol : class Sortable
location: class QuickSort
protected static int compare(Sortable a, Sortable b) {
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:20: cannot resolve symbol
symbol : class Sortable
location: class QuickSort
protected static int compare(Sortable a, Sortable b) {
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:26: cannot resolve symbol
symbol : class Sortable
location: class QuickSort
Sortable partitionElement;
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:29: cannot resolve symbol
symbol : class Sortable
location: class QuickSort
partitionElement = (Sortable)array.elementAt(end);
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:29: cannot resolve symbol
symbol : method elementAt (int)
location: interface java.util.List
partitionElement = (Sortable)array.elementAt(end);
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:34: cannot resolve symbol
symbol : class Sortable
location: class QuickSort
while (compare(partitionElement, (Sortable)array.elementAt(++left)) == 1) {
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:34: cannot resolve symbol
symbol : method elementAt (int)
location: interface java.util.List
while (compare(partitionElement, (Sortable)array.elementAt(++left)) == 1) {
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:37: cannot resolve symbol
symbol : class Sortable
location: class QuickSort
while (compare(partitionElement, (Sortable)array.elementAt(--right)) == -1) {
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:37: cannot resolve symbol
symbol : method elementAt (int)
location: interface java.util.List
while (compare(partitionElement, (Sortable)array.elementAt(--right)) == -1) {
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:41: swap(java.util.Vector,int,int) in QuickSort cannot be applied to (java.util.List,int,int)
swap(array, left, right);
^
C:\Documents and Settings\luna621\My Documents\Codes\QuickSort.java:43: swap(java.util.Vector,int,int) in QuickSort cannot be applied to (java.util.List,int,int)
swap(array, left, end);
^
11 errors

ASKER

Here's the Quicksort code:

import java.util.*;

public class QuickSort {

// Sorts entire array
public static void sort(List array) {
sort(array, 0, array.size() - 1);
} // END sort

// Sorts partial array
public static void sort(List array, int start, int end) {
int p;
if (end > start) {
p = partition(array, start, end);
sort(array, start, p-1);
sort(array, p+1, end);
} // END if
} // END sort

protected static int compare(Sortable a, Sortable b) {
return a.compare(b);
} // END compare

protected static int partition(List array, int start, int end) {
int left, right;
Sortable partitionElement;

// Arbitrary partition start...
partitionElement = (Sortable)array.elementAt(end);

left = start - 1;
right = end;
for (;;) {
while (compare(partitionElement, (Sortable)array.elementAt(++left)) == 1) {
if (left == end) break;
} // END while
while (compare(partitionElement, (Sortable)array.elementAt(--right)) == -1) {
if (right == start) break;
} // END while
if (left >= right) break;
swap(array, left, right);
} // END for
swap(array, left, end);

return left;
} // END partition

protected static void swap(Vector array, int i, int j) {
Object temp;

temp = array.elementAt(i);
array.setElementAt(array.elementAt(j), i);
array.setElementAt(temp, j);
} // END swap
} // END Quicksort

ASKER

Oops!!

protected static void swap(Vector array, int i, int j) {
Object temp;

Suppose to be:

protected static void swap(List array, int i, int j) {
Object temp;

Your Sortable class/interface seems to be missing

ASKER

Oh, okay wait. That was the wrong code :)

Let me try my other one.

ASKER

Aiyaya! I can't figure out what I'm suppose to do with my choosePivot method:

public class QuickSort {

// ---------------------------------------------------------
// Sorts the items in an array into ascending order.
// Precondition: theArray[first..last] is an array.
// Postcondition: theArray[first..last] is sorted.
// Calls: partition.
// ---------------------------------------------------------

public static void quickSort(Comparable[] theArray, int first, int last) {

int pivotIndex;

if (first < last) {
// create the partition: S1, Pivot, S2
pivotIndex = partition(theArray, first, last);
// sort regions S1 and S2
quickSort(theArray, first, pivotIndex-1);
quickSort(theArray, pivotIndex+1, last);
} // END if

} // END quickSort

// ---------------------------------------------------------
// Partitions an array for quicksort.
// Precondition: theArray[first..last] is an array;
// first <= last.
// Postcondition: Returns the index of the pivot element of
// theArray[first..last]. Upon completion of the method,
// this will be the index value lastS1 such that
// S1 = theArray[first..lastS1-1] < pivot
// theArray[lastS1] == pivot
// S2 = theArray[lastS1+1..last] >= pivot
// Calls: choosePivot.
// ---------------------------------------------------------

private static int partition(Comparable[] theArray, int first, int last) {

// tempItem is used to swap elements in the array
Comparable tempItem;
// place pivot in theArray[first]
choosePivot(theArray, first, last);
Comparable pivot = theArray[first]; // reference pivot

// initially, everything but pivot is in unknown
int lastS1 = first; // index of last item in S1

// move one item at a time until unknown region is empty

for (int firstUnknown = first + 1; firstUnknown <= last; ++firstUnknown) {
// Invariant: theArray[first+1..lastS1] < pivot
// theArray[lastS1+1..firstUnknown-1] >= pivot
// move item from unknown to proper region
if (theArray[firstUnknown].compareTo(pivot) < 0) {
// item from unknown belongs in S1
++lastS1;
tempItem = theArray[firstUnknown];
theArray[firstUnknown] = theArray[lastS1];
theArray[lastS1] = tempItem;
} // end if
// else item from unknown belongs in S2
} // end for

// place pivot in proper position and mark its location
tempItem = theArray[first];
theArray[first] = theArray[lastS1];
theArray[lastS1] = tempItem;
return lastS1;
} // end partition

// ---------------------------------------------------------
// Chooses a pivot for quicksort's partition algorithm and
// swaps it with the first item in an array.
// Precondition: theArray[first..last] is an array;
// first <= last.
// Postcondition: theArray[first] is the pivot.
// ---------------------------------------------------------

private static void choosePivot(Comparable[] theArray, int first, int last) {
// ???
// need to swap pivot w/ first
} // end choosePivot

} // END QuickSort

ASKER

Okay, how's this?

private static void choosePivot(Comparable[] theArray, int first, int last) {

int pivotIndex;
int mid = (first + last)/2;
if (theArray[first].compareTo(theArray[mid])<=0) {
if (theArray[mid] <= theArray[last]) {
pivotIndex = mid;
}
else {
pivotIndex = (theArray[first].compareTo(theArray[last])<=0 ? last : first);
}
}
else if(theArray[last] <= theArray[mid]) {
pivotIndex = mid;
}
else {
pivotIndex = (theArray[first] <= theArray[last] ? first:last);
swap(theArray, first pivotIndex);
}

} // end choosePivot

public void swap(int[] theArray, int left, int right) {

Comparable temp = theArray[left];
theArray[left] = theArray[right];
theArray[right] = temp;

} // end swap()

ASKER

Oh, darn:

C:\Documents and Settings\luna621\Codes\QuickSort.java:84: operator <= cannot be applied to java.lang.Comparable,java.lang.Comparable
if (theArray[mid] <= theArray[last]) {
^
C:\Documents and Settings\luna621\Codes\QuickSort.java:91: operator <= cannot be applied to java.lang.Comparable,java.lang.Comparable
else if(theArray[last] <= theArray[mid]) {
^
C:\Documents and Settings\luna621\Codes\QuickSort.java:95: operator <= cannot be applied to java.lang.Comparable,java.lang.Comparable
pivotIndex = (theArray[first] <= theArray[last] ? first:last);
^
C:\Documents and Settings\luna621\Codes\QuickSort.java:96: swap(int[],int,int) in QuickSort cannot be applied to (java.lang.Comparable[],int,int)
swap(theArray, first, pivotIndex);
^
C:\Documents and Settings\luna621\Codes\QuickSort.java:104: incompatible types
found : int
required: java.lang.Comparable
Comparable temp = theArray[left];
^
C:\Documents and Settings\luna621\Codes\QuickSort.java:106: incompatible types
found : java.lang.Comparable
required: int
theArray[right] = temp;
^
6 errors

http://mindprod.com/products.html#QUICKSORT

> if (theArray[mid] <= theArray[last]) {

should be:

if (theArray[mid].compareTo(theArray[last])<=0) {

similar for the others

ASKER

C:\Documents and Settings\luna621\My Documents\Codes\ReadInputArray.java:55: quickSort(java.lang.Comparable[],int,int) in QuickSort cannot be applied to (java.util.ArrayList)
QuickSort.quickSort(resultList);
^
1 error

I know I need the first and last elements of the list. How do I get that?

input.charAt(0) & input.charAt(len)??

ASKER

import java.io.*;
import java.util.*;

public class ReadInputArray {

public static void main (String[] arg) throws Exception {
// Read input array

BufferedReader readFile = new BufferedReader(new InputStreamReader(new FileInputStream("input.txt")));
String input = "";

File output = new File("output.txt"); // writes to output.txt
FileOutputStream outFromFile = new FileOutputStream(output);
PrintStream ps = new PrintStream(outFromFile);

try {

while((input = readFile.readLine())!=null) { // reads until there are no characters left

ArrayList resultList = new ArrayList(); // create new ArrayList for result
ArrayList digitsList = new ArrayList(); // create new ArrayList for ints

int len = input.length(); // length of input
StringBuffer sbDigits = new StringBuffer(); // create new string

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
char c = input.charAt(i);
if(c == ' ' || c == '\t') { // if the character is a space
if(sbDigits.length()>0) { // join the two together
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if
String space = c == ' ' ? " " : "\t" ;
resultList.add(space);
} // END if
else {
sbDigits.append(c);
} // END else
} // END for

if(sbDigits.length()>0){
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if

QuickSort.quickSort(resultList);

for(int i=0; i<resultList.size(); i++){
System.out.print(resultList.get(i));
ps.print(resultList.get(i)); // writes what was read to outout.txt
} // END for
} // END while
System.out.println("\n\nProcess complete. Please check your output.txt.\n");
} // END try

catch(NumberFormatException notInt) {
System.out.println("Input not in correct format. Integers only please.");
System.out.println("Program will now exit.\n");
} // END catch

} // END main()

} // END class ReadInputArray

If you are using JDK1.3 it is possible to use RMI over HTTP using special HTTP tunneling.
see http://java.sun.com/j2se/1.3/docs/guide/rmi/faq.html#firewall for details.
Hope that can help.

Sorry, I had a lot of windows open. That reply mentioned to be in another topic.

you need to convert your List to an array, using it toArray() method and sort that array.

ASKER

What do you mean?

public static void quickSort(Comparable[] theArray, int first, int last) {
theArray = (ArrayList)theArray;
...
}

No when you calling it, you have a List, but the QuickSort class expects an array.

QuickSort.quickSort((Comparable[])resultList.toArray(new Comparable[0], 0, resultList.size()-1);

ASKER

java:55: cannot resolve symbol
symbol : method toArray (java.lang.Comparable[],int,int)
location: class java.util.ArrayList
QuickSort.quickSort((Comparable[])resultList.toArray(new Comparable[0], 0, resultList.size()-1));
^
java:55: quickSort(java.lang.Comparable[],int,int) in QuickSort cannot be applied to (java.lang.Comparable[])
QuickSort.quickSort((Comparable[])resultList.toArray(new Comparable[0], 0, resultList.size()-1));
^
2 errors

Is this because I can't make the resultList a Comparable[]??

>Is this because I can't make the resultList a Comparable[]??

No.
Because the method quickSort give 3 parameters and you have specified only one.

Bye, Giant.

I believe your calling must be like following:
QuickSort.quickSort((Comparable[])resultList.toArray(), 0, resultList.size()-1));

woops, I missed a ). Also will need to keep a reference to the array:

Comparable[] array = (Comparable[])resultList.toArray(new Comparable[0]);
QuickSort.quickSort(array, 0, array.length-1);

ASKER

Exception in thread "main" java.lang.ClassCastException
at java.lang.Integer.compareTo(Integer.java:955
at QuickSort.choosePivot(QuickSort.java:83)
at QuickSort.partition(QuickSort.java:42)
at QuickSort.quickSort(QuickSort.java:16)
at ReadInputArray.main(ReadInputArray.java:57)

-----------------------------------------------------------------------
QuickSort.choosePivot(QuickSort.java:83)
>> if (theArray[first].compareTo(theArray[mid])<=0) {

QuickSort.partition(QuickSort.java:42)
>> choosePivot(theArray, first, last);

QuickSort.quickSort(QuickSort.java:16)
>> pivotIndex = partition(theArray, first, last);

ReadInputArray.main(ReadInputArray.java:57)
>> QuickSort.quickSort(array, 0, array.length-1);

Thats cause you are adding String's and Integer's to your list, and you cannot compare them to sort.

ASKER

Okay. Should I sort the integers first, then put them back into my digitsList? Then, combine it with the spaces after? Looks like I'll have to work on this tomorrow. I'll be back. Thank you for helping me so far!!

Depends how did you want them sorted

With the following code you can sort Integer and String.
from b c 3 a c 28 e c 5
to 3 5 28 a b c c c e
To put the String before the Integer you must only change the line:
else if (a[i] instanceof String && pivot instanceof Integer)//String must follows Integer
with:
else if (a[i] instanceof Integer && pivot instanceof String)//Integer must follows String

Hope this could help you.
Bye, Giant.

public class QuickSort {

      public static void main(String[] args) {
            Comparable[] aa = { "b", "c", new Integer(3), "a", "c", new Integer(28), "e", "c", new Integer(5)};
            QuickSort qs = new QuickSort();
            System.out.print("FROM:");
            for (int i = 0; i < aa.length; i++)
                  System.out.print(" " + aa[i]);
            System.out.println();
            qs.quicksort(aa, 0, aa.length - 1);
            System.out.print("TO:");
            for (int i = 0; i < aa.length; i++)
                  System.out.print(" " + aa[i]);
            System.out.println();
      }

      public void quicksort(Comparable[] a, int low, int high) {
            int pivot;
            /* Termination condition! */
            if (high > low) {
                  pivot = partition(a, low, high);
                  quicksort(a, low, pivot - 1);
                  quicksort(a, pivot + 1, high);
            }
      }

      private void swap(Comparable[] a, int posx, int posy) {
            Comparable el = a[posx];
            a[posx] = a[posy];
            a[posy] = el;
      }

      public int partition(Comparable[] a, int low, int high) {
            int piv = ((high - low) / 2) + low;
            Comparable pivot = a[piv];
            int last = high;
            int i = low;
            while (i < last) {
                  boolean invert = false;
                  if (a[i].getClass().getName().equals(pivot.getClass().getName()) && a[i].compareTo(pivot) >= 0)
                        invert = true;
                  else if (a[i] instanceof String && pivot instanceof Integer)//String must follows Integer
                        invert = true;
                  if (invert) {
                        if (piv == i) {
                              swap(a, piv, piv + 1);
                              piv = piv + 1;
                        } else {
                              swap(a, i, last);
                              if (piv == last) {
                                    piv = i;
                              }
                              last--;
                        } //end if else piv==i
                  } else
                        i++;
            } //end while i
            return piv;
      }

}

ASKER

cannot resolve symbol
symbol : method quicksort (java.lang.Comparable[],int,int)
location: class QuickSort
qs.quicksort(aa, 0, aa.length - 1);
^
1 error

I'm gonna try sorting the integers first. Then putting the sorted ints into the resultList. I'll probably have a lot of errors, so I'll be posting soon.

ASKER

Darn! It compiles, but it doesn't sort it:

ArrayList resultList = new ArrayList(); // create new ArrayList for result
ArrayList digitsList = new ArrayList(); // create new ArrayList for ints

int len = input.length(); // length of input
StringBuffer sbDigits = new StringBuffer(); // create new string

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
char c = input.charAt(i);
if(c == ' ' || c == '\t') { // if the character is a space
if(sbDigits.length()>0) { // join the two together
Comparable[] array = (Comparable[])digitsList.toArray(new Comparable[0]); <<<<<<
QuickSort.quickSort(array, 0, array.length-1); <<<<<<
sbDigits = (StringBuffer) sbDigits; <<<<<<
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if
String space = c == ' ' ? " " : "\t" ;
resultList.add(space);
} // END if
else {
sbDigits.append(c);
} // END else
} // END for

ASKER

Comment from Giant2
Date: 09/07/2004 05:17AM HST

With the following code you can sort Integer and String.
from b c 3 a c 28 e c 5
to 3 5 28 a b c c c e
----------------------------------------------------------------------------------
Thank you, I understand what you're saying. Sorry, I should have clarified. My program only excepts integers, spaces, and tabs. So, you can throw the String idea out :)

Basically, I just need my QuickSort to sort like how this did:

Collections.sort(digitsList);

int num=0;
for (int i=0; i<resultList.size(); i++){
if (resultList.get(i) instanceof Integer){
resultList.set(i,digitsList.get(num));
num++;
}// END if
}// END for

Example:

input: 11 _ 2 _ _ 53 <tab> 0 _ _ _ 28
output: 0 _ 2 _ _ 11 <tab> 28 _ _ _ 53

The code already takes care of the spaces and tabs. It's just the quicksort is not working.

ASKER

Comment from objects feedback
Date: 09/06/2004 11:16PM HST

Depends how did you want them sorted
-------------------------------------------------------------------------

Like how I have in my example above. Okay, changed the code a little, but it still doesn't work:

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
char c = input.charAt(i);
if(c == ' ' || c == '\t') { // if the character is a space
if(sbDigits.length()>0) { // join the two together

// Sort input array in increasing order
Comparable[] array = (Comparable[])digitsList.toArray(new Comparable[0]);
QuickSort.quickSort(array, 0, array.length-1);
resultList.add(new Integer(sbDigits.toString()));
sbDigits = new StringBuffer();
} // END if
String space = c == ' ' ? " " : "\t" ;
resultList.add(space);
} // END if
else {
sbDigits.append(c);
} // END else
} // END for

How do I add the Comparable[] array to the resultList? Or, is that not possible?

ASKER

Okay, how about if I forget about the spacing for now. So as long as the integers are separated by spaces or tabs, that line is an acceptable input. Then, have the quicksort sort it.

Example:

input: 8 _ _ 3 _ 24 _ _ _ 2 <tab> 66 _ 14
output: 2 _ 3 _ 8 _ 24 _ 66

you need to sort *after* you have added all the numbers to the list, no point sorting every time you add a number.
And then use the contents of the array *not* the contents of resultList (which remains in original order)

ASKER

Yeah, found that out the hard way :)

Anyways, I started over - tried to simplify it. Is this approach better?:

public static void main (String[] arg) throws Exception {

try {

// 1. Read a string from the file
BufferedReader in = new BufferedReader(new FileReader("input.txt"));
String input = "";

while ((input = in.readLine()) != null) {

try {
// process(input) - make sure input in correct format

// 2. Tokenize 'str' using a StringTokenizer and store all tokens into an array
StringTokenizer parser = new StringTokenizer(aString);

while (parser.hasMoreTokens()) {
//processWord(parser.nextToken()) - store into array
} // END while

// stop tokenizing

//3. Apply quicksort
// stop quicksort

//4. Write the string 'input' to the output.txt file.
// stop output

} // END try

catch(NumberFormatException notInt) {
System.out.println("Input not in correct format. Integers, spaces, or tabs only please.");
System.out.println("Program will now exit.\n");
System.exit(0);
} // end catch

} // END while

in.close();

// stop read from file

} // END try

catch (IOException e) {
System.out.println("Could not read from input.txt.");
System.out.println("Program will now exit.\n");
System.exit(0);
} // END catch

ASKER

>> // 2. Tokenize 'str' using a StringTokenizer and store all tokens into an array

Should read: // 2. Tokenize 'input' using a StringTokenizer and store all tokens into an array

I would suggest using Collections.sort() (mergesort nlog(n) performance) for easier programing.

ArrayList resultList = new ArrayList(); // create new ArrayList for result
ArrayList digitsList = new ArrayList(); // create new ArrayList for ints

while((input = readFile.readLine())!=null) { // reads until there are no characters left

int len = input.length(); // length of input
StringBuffer sbDigits = new StringBuffer(); // create new string

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
char c = input.charAt(i);
if(c == ' ' || c == '\t') { // if the character is a space
if(sbDigits.length()>0) { // join the two together
Integer num = new Integer(sbDigits.toString());
digitsList.add(num);
resultList.add(num);
sbDigits = new StringBuffer();
} // END if
String space = c == ' ' ? "_" : "\t" ;
resultList.add(space);
} // END if
else {
sbDigits.append(c);
} // END else
} // END for

if(sbDigits.length()>0){
Integer num = new Integer(sbDigits.toString());
digitsList.add(num);
resultList.add(num);
sbDigits = new StringBuffer();
} // END if

resultList.add("\n"); // new line
} // END while

int numIndex = 0;
Collections.sort(digitsList); // sort them
Iterator it = digitsList.iterator();
for(int i=0; i<resultList.size(); i++){
Object o = resultList.get(i);
if(o instanceof Integer)
{
o = it.hasNext() ? it.next() : "" ;
}
System.out.print(o);
ps.print(o); // writes what was read to outout.txt
} // END for

ASKER

> Comment from gnoon
> Date: 09/07/2004 05:05PM HST
>
> I would suggest using Collections.sort() (mergesort nlog(n) performance) for easier programing.
------------------------------------------------------------------------------------------------------------------------------------

Yes, someone previously suggested that (think it was in another post). But, I wanted my code to call on my QuickSort code (located in another class). That's why I decided to scrap the idea I started with. Forget about the spacing and the tabs in the right places. I just need to:

1. Check if input is correct: only integers, spaces, and tabs; no letters, special characters, etc.
Example of correct input: 10 _ 3 _ _ 4 <tab> 7
incorrect input: 1 _ abc _ * <tab> e4

2. Tokenize the string, and store into array.
array => |10 | 3 | 4 | 7 |

3. Quicksort array => | 3 | 4 | 7 |10 |

4. Pretty print array: 3 _ 4 _ 7 _ 10

ASKER

So, would I basically do the same thing:

ArrayList digitsList = new ArrayList(); // create new ArrayList for ints

while((input = readFile.readLine())!=null) { // reads until there are no characters left

int len = input.length(); // length of input
StringBuffer sbDigits = new StringBuffer(); // create new string

// reads through input to finds ints and spaces
for(int i=0; i<len; i++) {
if(sbDigits.length()>0) { // join the two together
Integer num = new Integer(sbDigits.toString());
digitsList.add(num);
sbDigits = new StringBuffer();
} // END if
} // END if
else {
sbDigits.append(c);
} // END else
} // END for

if(sbDigits.length()>0){
Integer num = new Integer(sbDigits.toString());
digitsList.add(num);
sbDigits = new StringBuffer();
} // END if
} // END while

ASKER

Whoops! Take this out:

else {
sbDigits.append(c);
} // END else

ASKER

Hmm... okay. I think it's not storing into the array. Ah! I need to Tokenize the string, then store it right? How would I do that?

while (input.hasMoreTokens()) {
digitsList.add(input.nextToken()); <<------------- ?????
} // END while

ASKER

StringTokenizer ints = new StringTokenizer(input);

while (ints.hasMoreTokens()) {
digitsList.add(ints.nextToken()); //<<------------- ?????
} // END while

ASKER

Okay, got it to Tokenize... but it's still not sorting...

while((input = readFile.readLine())!=null) { // reads until there are no characters left

StringTokenizer ints = new StringTokenizer(input);

while (ints.hasMoreTokens()) {
digitsList.add(ints.nextToken() + " ");
} // END while

Comparable[] array = (Comparable[])digitsList.toArray(new Comparable[0]);
QuickSort.quickSort(array, 0, array.length-1);

// Output the resulting array
for(int i=0; i<digitsList.size(); i++){
System.out.print(digitsList.get(i));
ps.print(digitsList.get(i)); // writes what was read to output.txt
} // END for
System.out.println("\n\nProcess complete. Please check your output.txt.\n");
} // END while

ASKER

Aiyaya! It's also accepting letters and special characters. How do I make it accept integers only?

ASKER

Okay, does this Tokenizer look better?

try {
// Read input from input.txt
while((input = readFile.readLine())!=null) { // reads until there are no characters left

// separates the ints from the spaces

StringBuffer sbDigits = new StringBuffer(); // create new string

StringTokenizer st = new StringTokenizer(input);
int numElements = 0;
if ((numElements = st.countTokens()) > 0) {
String[] tempString = input.split(" ");
int index = 0;
while (st.hasMoreTokens()) {
tempString[index++] = st.nextToken();
} // END while
} // END if

// need to sort...

// Output the resulting array
for(int i=0; i<digitsList.size(); i++){
System.out.print(digitsList.get(i));
ps.print(digitsList.get(i)); // writes what was read to output.txt
} // END for
System.out.println("\n\nProcess complete. Please check your output.txt.\n");
} // END while
} // END try

// checks for data in correct format - integers, spaces, and tabs only
catch(NumberFormatException notInt) {
System.out.println("Input not in correct format. Integers, spaces, or tabs only please.");
System.out.println("Program will now exit.\n");
} // END catch

ASKER

How do I make it an integer array instead of a String array. I tried changing it to int[], but it wouldn't let me use the .split()...

String[] intArray = input.split(" ");
int index = 0;
while (st.hasMoreTokens()) {
intArray[index++] = st.nextToken();

} // END while

ASKER

Okay, this page is starting to get too long. I'll post another question to continue this one. Thank you for all who helped :)

>Forget about the spacing and the tabs in the right places.
>I just need to:
> 1. Check if input is correct: only integers, spaces, and tabs; no letters, special characters, etc.
> 2. ...

There's a class, named StreamTokenizer, which can get only numbers from a string(read from file) and can check for non-digit character. It's easy to use. :)

Thank for acceptation.