help with an error please

**Ganon11** · Mar 13 '07, 03:50 PM

Shouldn't the enter key produce a newline character? Then you can check

Code:

if (DataBits == '\n')

You can't compare a char with null because char is not a class, but a native type.

**r035198x** · Mar 14 '07, 07:17 AM

Originally posted by JavaStudent07

I am trying to test a character for being the "Enter" key, I figured to test it
if(DataBits!=nu ll)
{
stuff
}
like that, but i got
H:\>c:\j2sdk1.4 .1\bin\javac.ex e BubbleSort.java
BubbleSort.java :68: operator != cannot be applied to char,<nulltype>
if(DataBits!=nu ll)
^
1 error

if you could please submit a reasonably simple solution I would be very happy, thanks ahead of time for your time.

Steve

Oh dear. What are you trying to do now JavaStudent?

Just explain what you want to achieve and I'm sure there is a simple way of doing it.

**JavaStudent07** · Mar 14 '07, 03:04 PM

the same program as before lol, three months, probably take you guys one if that XD jeez lol...oh well thanks for the tip :)

**JavaStudent07** · Mar 14 '07, 03:09 PM

Code:

/*
Steve Glasser
January 6,2007
BubbleSort
*/

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

public class BubbleSort
{
public static void main (String args[]) throws Exception
{
//while(DataBits == '\n')
//{
Sort();
//}
}
//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static void Sort()throws Exception
{

int Averages[];
String filage="";
char DataBits='A';
String Number="";
char array[];
int PlaceHolder=0;
int ArrayLength=0;
int intN=0;

BufferedReader inWords=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please input the name of the file from which the data will be acquired.  Be sure to use the entire path.");

filage=inWords.readLine();
BufferedReader inData=new BufferedReader(new FileReader(filage));
String Data=inData.readLine();
System.out.println(Data);
array=Data.toCharArray();
ArrayLength=array.length;
System.out.println(ArrayLength);
DataBits=Data.charAt(PlaceHolder);
final int ARRAY_SIZE=(ArrayLength-1);
int NumArray[];
NumArray=new int[ARRAY_SIZE];

while(PlaceHolder<ArrayLength)
{

while(DataBits!=' ')
{
if(PlaceHolder<ArrayLength)
{
System.out.println("PlaceHolder: "+PlaceHolder);
System.out.println("Character:"+DataBits);
Number=(Number+DataBits);
PlaceHolder=(PlaceHolder+1);
DataBits=(Data.charAt(PlaceHolder));
}
}

NumArray[intN]=seekArray(Number);
System.out.println("Final Concatenated Result of While: "+NumArray[intN]);
intN++;
Number="";

if(PlaceHolder<ArrayLength)
{
System.out.println("PlaceHolder: "+PlaceHolder);
System.out.println("Character: *Blank*");
PlaceHolder++;
DataBits=(Data.charAt(PlaceHolder));
}
}
System.out.println("In sorted order, the numbers go:");
seekOrder(NumArray, intN);
}
//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static int seekArray(String Number)
{
int Numerical=Integer.parseInt(Number);

return(Numerical);
}

//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static void seekOrder(int NumArray[], int intN)
{
int swapped=0;
int swap=0;
int N=0;



for(N=1; N<intN; N++)
{
	while(swapped==0)
	{
        while(NumArray[N]>NumArray[N-1])
           {
	   if(NumArray[N]>NumArray[N + 1]) 
           {     
	   swap=NumArray[N];
	   NumArray[N]=NumArray[N+1];
	   NumArray[N+1]=swap;
           }
	   swapped=0; 
	   }//end while
        if(swapped==0)
        {
	swapped=1;
        }
	}//end while
}//end for
seekPrint(NumArray, intN);
}//end Order
//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static void seekPrint(int NumArray[], int intN)
{
int intTest=0;
int intTest1=0;

for(intTest=intN; intTest>=0; intTest--)
{
intTest1=intN;
System.out.println(NumArray[intTest1]);
intTest1--;
}
}
}

thats the code

**JavaStudent07** · Mar 14 '07, 03:10 PM

67 34 5 6 23 12
56 100 97 97 85
78 67 90
452 78 345 67 888 78

^^^^^
thats the numbers inputted, at the moment i am workin on the first line only

**JavaStudent07** · Mar 14 '07, 03:11 PM

H:\>c:\j2sdk1.4 .1\bin\java.exe BubbleSort
Please input the name of the file from which the data will be acquired. Be sure to use the entire pat
h:\Numbers.txt
67 34 5 6 23 12
16
PlaceHolder: 0
Character:6
PlaceHolder: 1
Character:7
Final Concatenated Result of While: 67
PlaceHolder: 2
Character: *Blank*
PlaceHolder: 3
Character:3
PlaceHolder: 4
Character:4
Final Concatenated Result of While: 34
PlaceHolder: 5
Character: *Blank*
PlaceHolder: 6
Character:5
Final Concatenated Result of While: 5
PlaceHolder: 7
Character: *Blank*
PlaceHolder: 8
Character:6
Final Concatenated Result of While: 6
PlaceHolder: 9
Character: *Blank*
PlaceHolder: 10
Character:2
PlaceHolder: 11
Character:3
Final Concatenated Result of While: 23
PlaceHolder: 12
Character: *Blank*
PlaceHolder: 13
Character:1
PlaceHolder: 14
Character:2
Final Concatenated Result of While: 12
PlaceHolder: 15
Character: *Blank*
Exception in thread "main" java.lang.Strin gIndexOutOfBoun dsException: String index out of range: 16
at java.lang.Strin g.charAt(String .java:460)
at BubbleSort.Sort (BubbleSort.jav a:72)
at BubbleSort.main (BubbleSort.jav a:16)

^^^^^^^
thats the print out

**JavaStudent07** · Mar 14 '07, 03:13 PM

input lines of numbers from a separate file and sort them from highest to lowest order

^^^
thats the task,

PS: there are spaces at the end of each data line otherwise it cuts off the last number, it just worked, i dont know...

Thanks in advance for ANY HELP lol

Steve

**r035198x** · Mar 14 '07, 03:23 PM

Originally posted by JavaStudent07

Code:

/*
Steve Glasser
January 6,2007
BubbleSort
*/
 
import java.io.*;
import java.util.*;
 
public class BubbleSort
{
public static void main (String args[]) throws Exception
{
//while(DataBits == '\n')
//{
Sort();
//}
}
//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static void Sort()throws Exception
{
 
int Averages[];
String filage="";
char DataBits='A';
String Number="";
char array[];
int PlaceHolder=0;
int ArrayLength=0;
int intN=0;
 
BufferedReader inWords=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Please input the name of the file from which the data will be acquired. Be sure to use the entire path.");
 
filage=inWords.readLine();
BufferedReader inData=new BufferedReader(new FileReader(filage));
String Data=inData.readLine();
System.out.println(Data);
array=Data.toCharArray();
ArrayLength=array.length;
System.out.println(ArrayLength);
DataBits=Data.charAt(PlaceHolder);
final int ARRAY_SIZE=(ArrayLength-1);
int NumArray[];
NumArray=new int[ARRAY_SIZE];
 
while(PlaceHolder<ArrayLength)
{
 
while(DataBits!=' ')
{
if(PlaceHolder<ArrayLength)
{
System.out.println("PlaceHolder: "+PlaceHolder);
System.out.println("Character:"+DataBits);
Number=(Number+DataBits);
PlaceHolder=(PlaceHolder+1);
DataBits=(Data.charAt(PlaceHolder));
}
}
 
NumArray[intN]=seekArray(Number);
System.out.println("Final Concatenated Result of While: "+NumArray[intN]);
intN++;
Number="";
 
if(PlaceHolder<ArrayLength)
{
System.out.println("PlaceHolder: "+PlaceHolder);
System.out.println("Character: *Blank*");
PlaceHolder++;
DataBits=(Data.charAt(PlaceHolder));
}
}
System.out.println("In sorted order, the numbers go:");
seekOrder(NumArray, intN);
}
//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static int seekArray(String Number)
{
int Numerical=Integer.parseInt(Number);
 
return(Numerical);
}
 
//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static void seekOrder(int NumArray[], int intN)
{
int swapped=0;
int swap=0;
int N=0;
 
 
 
for(N=1; N<intN; N++)
{
	while(swapped==0)
	{
while(NumArray[N]>NumArray[N-1])
{
	 if(NumArray[N]>NumArray[N + 1]) 
{ 
	 swap=NumArray[N];
	 NumArray[N]=NumArray[N+1];
	 NumArray[N+1]=swap;
}
	 swapped=0; 
	 }//end while
if(swapped==0)
{
	swapped=1;
}
	}//end while
}//end for
seekPrint(NumArray, intN);
}//end Order
//V^V^V^V^V^V^V^V^V^V^V^V^^V^V^V^V^V^V^V^V^V^V^V^V^V^V^V^
public static void seekPrint(int NumArray[], int intN)
{
int intTest=0;
int intTest1=0;
 
for(intTest=intN; intTest>=0; intTest--)
{
intTest1=intN;
System.out.println(NumArray[intTest1]);
intTest1--;
}
}
}

thats the code

Ok let me just say the following.

Suppose you have a text file say

Code:

 String fileName = "test.txt";

and having openined it nicely for reading with

Code:

 
BufferedReader inData=new BufferedReader(new FileReader(fileName));

If you then wish to read one line of data from the file, the first line, then you would do

Code:

 String firstLine = inData.readLine();

To read the second line, then you should call readLine again like this

Code:

 String secondLine = inData.readLine();

So this is all very well. Just call readLine() to get the next line of data from the file.

If you wish to read all the lines of the tex file then you are in need of a while loop that reads until the line line has been read.

Now how do we know we have reached the last line? Well readLine() simply returns null if you call it after the last line. So your while loop would look something like this

Code:

 
BufferedReader inData=new BufferedReader(new FileReader(fileName));
String line = inData.readLine(); 
while(line != null) {
	 //do stuff with the line
 
	  line = inData.readLine(); 
}

Having said all that, I now await an explanation from you of where you wanted to know the codes of the enter key being pressed e.t.c ...

**r035198x** · Mar 14 '07, 03:25 PM

Originally posted by JavaStudent07

input lines of numbers from a separate file and sort them from highest to lowest order

^^^
thats the task,

PS: there are spaces at the end of each data line otherwise it cuts off the last number, it just worked, i dont know...

Thanks in advance for ANY HELP lol

Steve

You mean it just worked as in correctly, no error/exception/incorrect results?

**JavaStudent07** · Mar 14 '07, 03:34 PM

Originally posted by r035198x

You mean it just worked as in correctly, no error/exception/incorrect results?

H:\>c:\j2sdk1.4 .1\bin\java.exe BubbleSort
Please input the name of the file from which the data will be acquired. Be sure to use the entire path
h:\Numbers.txt
67 34 5 6 23 12
15
PlaceHolder: 0
Character:6
PlaceHolder: 1
Character:7
Final Concatenated Result of While: 67
PlaceHolder: 2
Character: *Blank*
PlaceHolder: 3
Character:3
PlaceHolder: 4
Character:4
Final Concatenated Result of While: 34
PlaceHolder: 5
Character: *Blank*
PlaceHolder: 6
Character:5
Final Concatenated Result of While: 5
PlaceHolder: 7
Character: *Blank*
PlaceHolder: 8
Character:6
Final Concatenated Result of While: 6
PlaceHolder: 9
Character: *Blank*
PlaceHolder: 10
Character:2
PlaceHolder: 11
Character:3
Final Concatenated Result of While: 23
PlaceHolder: 12
Character: *Blank*
PlaceHolder: 13
Character:1
PlaceHolder: 14
Character:2
Exception in thread "main" java.lang.Strin gIndexOutOfBoun dsException: String index out of range: 15
at java.lang.Strin g.charAt(String .java:460)
at BubbleSort.Sort (BubbleSort.jav a:58)
at BubbleSort.main (BubbleSort.jav a:16)
^^^^^^
without the spaces after it, it cuts off the whole last number, the !null thing i asked for is at the top of the program where it runs the main "Sort" method, i slashed it out for now but i will try to work with that once i get the base program going.

**JavaStudent07** · Mar 14 '07, 03:44 PM

its time to go, i will check responses tommorow, good luck understanding a begginers slaughter of a program :-P

**Ganon11** · Mar 14 '07, 08:19 PM

Maybe you can check if PlaceHolder is greater than the length of the string before getting the new DataBits value - if PlaceHolder IS greater, break from the while loop.

**JavaStudent07** · Mar 15 '07, 03:08 PM

Originally posted by Ganon11

Maybe you can check if PlaceHolder is greater than the length of the string before getting the new DataBits value - if PlaceHolder IS greater, break from the while loop.

:) it doesn't work yet, lmao but thanks :) :) it at least doesn't have that gay error w00t

help with an error please

help with an error please

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment