Thread: Array Lists help!!

sCurrentLine = s.readLine()) != null

First off,

sCurrentLine ==s.readLine()

while ((sCurrentLine = s.readLine()) != null) {

This line won't work.

while((sCurrentLIne == s.readLine()) && (s.readLine() !=null)

might work.

mat = pat.matcher(sCurrentLine);

sCurrentLine hasn't been initialized yet.

// Print line as read from file
System.out.println(sCurrentLine)

Well, to just print out the lines alone read from the file without doing anything to them,

well....you'd need to define the FileReader first before you do. But after that

while (inFile.hasNext())
{
sCurrentLine = inFile.nextLine();
System.out.prinltn(sCurrentLine);
}

int n = myArray.size();
for (int i = 0; i < n; i++) {
System.out.println(myArray.get(i));
}

You never added anything.

Your size will be 0.

You have to

myArray.add(int index, Integer data);

Originally Posted by javapenguin

// Print line as read from file
System.out.println(sCurrentLine)

Well, to just print out the lines alone read from the file without doing anything to them,

well....you'd need to define the FileReader first before you do. But after that

while (inFile.hasNext())
{
sCurrentLine = inFile.nextLine();
System.out.prinltn(sCurrentLine);
}

Yes i knew that but the problem was that i wanted to separate the numbers from the text and the symbols. That's where i messed up. I managed to do the first thing (read and seperate the integers) but i can't understand how to create the array list from the code i have...

thank you for your answers but could you be a little more specific cause i m really new to java.

Originally Posted by javapenguin

int n = myArray.size();
for (int i = 0; i < n; i++) {
System.out.println(myArray.get(i));
}

You never added anything.

Your size will be 0.

You have to

myArray.add(int index, Integer data);

You are absolutely right but i dont know how to fill: myArray.add(int index, Integer data); with the integers i found when i read the file. Whta is my index and what is my data?

Sorry for the stupid questions :-(

Well, to separate the numbers and the text and symbols, maybe you could use a StringTokenizer.
StringTokenizer (Java 2 Platform SE v1.4.2)

Originally Posted by javapenguin

For starters, what exactly are you trying to add?

Each number individually, each number as a pair, each number as a pair with reference to another pair?

To add it, do something perhaps like this:

StringTokenizer tokenizer = new StringTokenizer(sCurrentLine);

String temp = tokenizer.nextToken();

if (temp.equals("("))
ignore Token and go on

else if (temp.equals(")"))
ignore Token and go on

else if (temp.equals("->>>>>noise->>>>"))
ignore Token and go on

else if (temp.equals(","))
ignore Token and go on

else
{

Integer temp2 = Integer.parseInt(token);

myArray.add(temp2);

}

Also, I'm sorry earlier. There are two possible add methods for ArrayList.

add(E data) adds the data to the end of your ArrayList

add(int index, E data) adds the data at the index index of your ArrayList.

Thank you so much! I will try that and tell you about it! I am trying to add each number individually to an array list.I hope it will work!

Originally Posted by javapenguin

while ((sCurrentLine = s.readLine()) != null) {

This line won't work.

Yes, it will work..

To add values to an arraylist, just call the add function, not index is necessary when appending to the List

I wrote it this way I don't know if I did it right, but there are errors on the lines with "ignore Token and go on;"

Am I missing something???

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.StringTokenizer;
 
public class Main {
 private static String token;
 
    public static void main(String[] args) throws IOException {
 
 String sCurrentLine;
ArrayList<Integer> myArray = new ArrayList<Integer>();
 BufferedReader s = null;
 s = new BufferedReader(new FileReader("measurements.txt"));
 
while ((sCurrentLine = s.readLine()) != null) {
 
StringTokenizer tokenizer = new StringTokenizer(sCurrentLine);
 
String temp = tokenizer.nextToken();
 
if (temp.equals("(")){
ignore Token and go on;
 
} else if (temp.equals(")")){
ignore Token and go on;
 
}else if (temp.equals("->>>>>noise->>>>")){
ignore Token and go on;
 
    }
    else{
 
                }
   if (temp.equals(",")) {
ignore Token and go on;
 
    }
    else
{
 
Integer temp2 = Integer.parseInt(token);
 
myArray.add(temp2);
 
}
        }
    }
    }

The output is:

Exception in thread "main" java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:417)
at java.lang.Integer.parseInt(Integer.java:499)
at xristina.Main.main(Main.java:45)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

sCurrentLIne = s.readLine();

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.StringTokenizer;
 
public class Main {
 private static String token;
 
    public static void main(String[] args) throws IOException {
 
 String sCurrentLine;
ArrayList<Integer> myArray = new ArrayList<Integer>();
 BufferedReader s = null;
 s = new BufferedReader(new FileReader("measurements.txt"));
 
while ((sCurrentLine = s.readLine()) != null) {
sCurrentLine = s.readLine(); // you were missing this part
 
StringTokenizer tokenizer = new StringTokenizer(sCurrentLine);
 
String temp = tokenizer.nextToken();
 
if (temp.equals("(")){
ignore Token and go on;
 
} else if (temp.equals(")")){
ignore Token and go on;
 
}else if (temp.equals("->>>>>noise->>>>")){
ignore Token and go on;
 
    }
    else{
 
                }
   if (temp.equals(",")) {
ignore Token and go on;
 
    }
    else
{
 
Integer temp2 = Integer.parseInt(token);
 
myArray.add(temp2);
 
}
        }
    }
    }

Also, you have an empty else.

Yes i saw that and corrected it! It s late at night here!Sorry for that! But still the same errors in the "ignore Token and go on;" lines..

package xristina;
 
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.StringTokenizer;
 
public class Main {
 private static String token;
 
    public static void main(String[] args) throws IOException {
 
 String sCurrentLine;
ArrayList<Integer> myArray = new ArrayList<Integer>();
 BufferedReader s = null;
 s = new BufferedReader(new FileReader("measurements.txt"));
 
while ((sCurrentLine = s.readLine()) != null) {
sCurrentLine = s.readLine(); // you were missing this part
 
StringTokenizer tokenizer = new StringTokenizer(sCurrentLine);
 
String temp = tokenizer.nextToken();
 
if (temp.equals("(")){
ignore Token and go on;
 
} else if (temp.equals(")")){
ignore Token and go on;
 
}else if (temp.equals("->>>>>noise->>>>")){
ignore Token and go on;
 
    }
    else{
 
 
   if (temp.equals(",")) {
ignore Token and go on;
 
    }
    else
{
 
Integer temp2 = Integer.parseInt(token);
 
myArray.add(temp2);
 
 }
 }
 }
 }
 }

I don't mean to tire you. You are really helpfull. I must be doing something wrong but I m sure I ll Find it!