Develop Reference

Read file using delimiter and add to array

I am trying to read from a text file that is in my project workspace then;
Create an object depending on the first element on the first line of the file
Set some variables within the object
Then add it to my arrayList
I seem to be reading the file ok but am struggling to create the different objects based off what the first element on each line in the text file is
Text file is like this
ul,1,gg,0,33.0
sl,2,hh,0,44.0
My expected result is to create an UltimateLanding object or StrongLanding object based on the first element in the text above file example
Disclaimer - I know the .equals is not correct to use in the IF statement, i've tried many ways to resolve this
My Code -
Edited -
It seems the program is now reading the file and correctly and adding to the array. However, it is only doing this for the first line in the file? There should be 2 objects created as there are 2 lines in the text file.
Scanner myFile = new Scanner(fr);
String line;
myFile.useDelimiter(",");
while (myFile.hasNext()) {
line = myFile.next();
if (line.equals("sl")) {
StrongLanding sl = new StrongLanding();
sl.setLandingId(Integer.parseInt(myFile.next()));
sl.setLandingDesc(myFile.next());
sl.setNumLandings(Integer.parseInt(myFile.next()));
sl.setCost(Double.parseDouble(myFile.next()));
landings.add(sl);
} else if (line.equals("ul")) {
UltimateLanding ul = new UltimateLanding();
ul.setLandingId(Integer.parseInt(myFile.next()));
ul.setLandingDesc(myFile.next());
ul.setNumLandings(Integer.parseInt(myFile.next()));
ul.setCost(Double.parseDouble(myFile.next()));
landings.add(ul);
}
}
TIA

There are multiple issues with your current code.
myFile.equals("sl") compares your Scanner object with a String. You would actually want to compare your read string line, not your Scanner object. So line.equals("sl").
nextLine() will read the whole line. So line will never be equal to "sl". You should split the line using your specified delimiter, then use the split parts to build your object. This way, you will not have to worry about newline in combination with next().
Currently, your evaluation of the read input is outside of the while loop, so you will read all the content of the file, but only evaluate the last line (currently). You should move the evaluation of the input and creation of your landing objects inside the while loop.
All suggestions implemented:
...
Scanner myFile = new Scanner(fr);
// no need to specify a delimiter, since you want to read line by line
String line;
String[] splitLine;
while (myFile.hasNextLine()) {
line = myFile.nextLine();
splitLine = line.split(","); // split the line by ","
if (splitLine[0].equals("sl")) {
StrongLanding sl = new StrongLanding();
sl.setLandingId(Integer.parseInt(splitLine[1]));
sl.setLandingDesc(splitLine[2]);
sl.setNumLandings(Integer.parseInt(splitLine[3]));
sl.setCost(Double.parseDouble(splitLine[4]));
landings.add(sl);
} else if (splitLine[0].equals("ul")) {
UltimateLanding ul = new UltimateLanding();
ul.setLandingId(Integer.parseInt(splitLine[1]));
ul.setLandingDesc(splitLine[2]);
ul.setNumLandings(Integer.parseInt(splitLine[3]));
ul.setCost(Double.parseDouble(splitLine[4]));
landings.add(ul);
}
}
...
However, if you don't want to read the contents line by line (due to whatever requirement you have), you can keep reading it via next(), but you have to specify the delimiter correctly:
...
Scanner myFile = new Scanner(fr);
String line; // variable naming could be improved, since it's not the line
myFile.useDelimiter(",|\\n"); // comma and newline as delimiters
while (myFile.hasNext()) {
line = myFile.next();
if (line.equals("sl")) {
StrongLanding sl = new StrongLanding();
sl.setLandingId(Integer.parseInt(myFile.next()));
sl.setLandingDesc(myFile.next());
sl.setNumLandings(Integer.parseInt(myFile.next()));
sl.setCost(Double.parseDouble(myFile.next()));
landings.add(sl);
} else if (line.equals("ul")) {
UltimateLanding ul = new UltimateLanding();
ul.setLandingId(Integer.parseInt(myFile.next()));
ul.setLandingDesc(myFile.next());
ul.setNumLandings(Integer.parseInt(myFile.next()));
ul.setCost(Double.parseDouble(myFile.next()));
landings.add(ul);
}
}
...

A solution.
List<Landing> landings = Files.lines(Paths.get("LandingsData.txt")).map(line -> {
String[] split = line.split(",");
if (split[0].equals("sl")) {
StrongLanding sl = new StrongLanding();
sl.setLandingId(Integer.parseInt(split[1]));
sl.setLandingDesc(split[2]);
sl.setNumLandings(split[3]);
sl.setCost(Double.parseDouble(split[4]));
return sl;
} else if (split[0].equals("ul")) {
UltimateLanding ul = new UltimateLanding();
ul.setLandingId(Integer.parseInt(split[1]));
ul.setLandingDesc(split[2]);
ul.setNumLandings(split[3]);
ul.setCost(Double.parseDouble(split[4]));
return ul;
}
return null;
}).filter(t -> t!= null).collect(Collectors.toList());

Why is the file reading the last line of a row and the first one of the second row

While reading a Excel CSV file using a scanner with a comma delimiter, its reading the last node in the first row but also reading the first node of the next row at the same time.
int counter = 0;
String[] u = new String[3];
for (int j = 1; j <= 3; j++) {
String a = in.next();
u[counter] = a;
counter++;
}
}
After using Debugger, I noticed when it reached to the last element it combined them making something like -14256\r\n-14323
-14256 = Last element of first row
-14323 = First element of next row

The scanner took only the comma as the delimiter. But you want it to accept also the end of a line as another delimiter.
I assume that you instantiate the Scanner like this, using Scanner::useDelimiter:
Scanner s = new Scanner( inputStream ).useDelimiter( "," );
If I get the Pattern definition right, it should be:
Scanner s = new Scanner( inputStream ).useDelimiter( ",|\\R" );
The \R stands for
Linebreak matcher: Any Unicode linebreak sequence, is equivalent to \u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029]
Refer to the documentation for java.util.regex.Pattern for the details.

A CSV file contains lines of text where each line contains values separated by commas. Hence I suggest that you read the file line by line and then split each line on the commas. Something like...
java.io.FileReader fr = new java.io.FileReader("path to file");
java.io.BufferedReader br = new java.io.BufferedReader(fr);
String line = br.readLine();
while (line != null) {
String[] fields = line.split(",");
// Add code here to handle the "fields".
line = br.readLine();
}
Note that the above code is not a complete solution but a starting point. For instance, I haven't closed the BufferedReader.

Searching a text file in java and Listing the results

I've really searched around for ideas on how to go about this, and so far nothing's turned up.
I need to search a text file via keywords entered in a JTextField and present the search results to a user in an array of columns, like how google does it. The text file has a lot of content, about 22,000 lines of text. I want to be able to sift through lines not containing the words specified in the JTextField and only present lines containing at least one of the words in the JTextField in rows of search results, each row being a line from the text file.
Anyone has any ideas on how to go about this? Would really appreciate any kind of help. Thank you in advance

You can read the file line by line and search in every line for your keywords. If you find one, store the line in an array.
But first split you text box String by whitespaces and create the array:
String[] keyWords = yourTextBoxString.split(" ");
ArrayList<String> results = new ArrayList<String>();
Reading the file line by line:
void readFileLineByLine(File file) {
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
processOneLine(line);
}
br.close();
}
Processing the line:
void processOneLine(String line) {
for (String currentKey : keyWords) {
if (line.contains(currentKey) {
results.add(line);
break;
}
}
}
I have not testst this, but you should get a overview on how you can do this.
If you need more speed, you can also use a RegularExpression to search for the keywords so you don't need this for loop.

Read in file, as per the Oracle tutorial, http://docs.oracle.com/javase/tutorial/essential/io/file.html#textfiles Iterate through each line and search for your keyword(s) using String's contain method. If it contains the search phrase, place the line and line number in a results List. When you've finished you can display the results list to the user.

You need a method as follows:
List<String> searchFile(String path, String match){
List<String> linesToPresent = new ArrayList<String>();
File f = new File(path);
FileReader fr;
try {
fr = new FileReader(f);
BufferedReader br = new BufferedReader(fr);
String line;
do{
line = br.readLine();
Pattern p = Pattern.compile(match);
Matcher m = p.matcher(line);
if(m.find())
linesToPresent.add(line);
} while(line != null);
br.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return linesToPresent;
}
It searches a file line by line and checks with regex if a line contains a "match" String. If you have many Strings to check you can change the second parameter to String[] match and with a foreach loop check for each String match.

You can use :
FileUtils
This will read each line and return you a List<String>.
You can iterate over this List<String> and check whether the String contains the word entered by the user, if it contains, add it to another List<String>. then at the end you will be having another List<String> which contains all the lines which contains the word entered by the user. You can iterate this List<String> and display the result to the user.

Read text file and split each newline into a string array

So basically I'm reading a text file that has a bunch of lines. I need to extract certain lines from the text file and add those specific lines into string array. I've been trying to split each newLine with: "\n" , "\r". This did not work. I keep getting this error as well:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at A19010.main(A19010.java:47)
Here is the code:
Path objPath = Paths.get("dirsize.txt");
if (Files.exists(objPath)){
File objFile = objPath.toFile();
try(BufferedReader in = new BufferedReader(
new FileReader(objFile))){
String line = in.readLine();
while(line != null){
String[] linesFile = line.split("\n");
String line0 = linesFile[0];
String line1 = linesFile[1];
String line2 = linesFile[2];
System.out.println(line0 + "" + line1);
line = in.readLine();
}
}
catch(IOException e){
System.out.println(e);
}
}
else
{
System.out.println(
objPath.toAbsolutePath() + " doesn't exist");
}

String[] linesFile = new String[] {line}; // this array is initialized with a single element
String line0 = linesFile[0]; // fine
String line1 = linesFile[1]; // not fine, the array has size 1, so no element at second index
String line2 = linesFile[2];
You're creating a String[] linesFile with one element, line, but then trying to access elements at index 1 and 2. This will give you an ArrayIndexOutOfBoundsException
You're not actually splitting anything here. in.readLine();, as the method says, reads a full line from the file.
Edit: You can add lines (Strings) dynamically to a list instead of an array, since you don't know the size.
List<String> lines = new LinkedList<String>(); // create a new list
String line = in.readLine(); // read a line at a time
while(line != null){ // loop till you have no more lines
lines.add(line) // add the line to your list
line = in.readLine(); // try to read another line
}

readLine() method reads a entire line from the input but removes the newLine characters from it. When you split the line on \n character, you will not find one in the String. Hence, you get the exception.
Please, refer the answer in this link for more clarity.

You are initializing your String array with 1 element, namely line. linesFile[0] is therefore line and the rest of your array is out of bounds.

Try this:
String[] linesFile = line.split("SPLIT-CHAR-HERE");
if(linesFile.length >= 3)
{
String line0 = linesFile[0];
String line1 = linesFile[1];
String line2 = linesFile[2];
// further logic here
}else
{
//handle invalid lines here
}

You are using array to store the strings. Instead use ArrayList from Java as ArrayList are dynamically growing. after your reading operation completes convert it into array.
String line = in.readLine();
ArrayList<String> str_list = new ArrayList<String>();
String[] strArr = new String[str_list.size()];
while(line != null){
str_list.add(line);
line = in.readLine();
}
// at the end of the operation convert Arraylist to array
return str_list.toArray(strArr);

The issue here is that you are creating a new String array every time your parser reads in a new line. You then populate only the very first element in that String array with the line that is being read in with:
String[] linesFile = new String[] {line};
Since you create a new String[] with one element every single time your while loop runs from the top, you lose the values it stored from the previous iteration.
The solution is to use new String[]; right before you enter the while loop. If you don't know how to use ArrayList, then I suggest a while loop like this:
int numberOfLine = 0;
while (in.readLine() != null)
{
numberOfLine++;
}
String linesFile = new String[numberOfLine];
This will let you avoid using a dynamically resized ArrayList because you know how many lines your file contains from the above while loop. Then you would keep an additional counter (or resuse numberOfLine since we have no use for it anymore) so that you can populate this array:
numberOfLine = 0;
in = new BufferedReader(new FileReader(objFile)); // reset the buffer
while ((String line = in.readLine()) != null)
{
linesFile[numberOfLine] = line;
numberOfLine++;
}
At this point linesFile should be correctly populated with the lines in your file, such that linesFile[i] can be used to access the i'th line in the file.

Split text file into Strings on empty line

I want to read a local txt file and read the text in this file. After that i want to split this whole text into Strings like in the example below .
Example :
Lets say file contains-
abcdef
ghijkl
aededd
ededed
ededfe
efefeef
efefeff
......
......
I want to split this text in to Strings
s1 = abcdef+"\n"+ghijkl;
s2 = aededd+"\n"+ededed;
s3 = ededfe+"\n"+efefeef+"\n"+efefeff;
........................
I mean I want to split text on empty line.
I do know how to read a file. I want help in splitting the text in to strings

you can split a string to an array by
String.split();
if you want it by new lines it will be
String.split("\\n\\n");
UPDATE*
If I understand what you are saying then john.
then your code will essentially be
BufferedReader in
= new BufferedReader(new FileReader("foo.txt"));
List<String> allStrings = new ArrayList<String>();
String str ="";
while(true)
{
String tmp = in.readLine();
if(tmp.isEmpty())
{
if(!str.isEmpty())
{
allStrings.add(str);
}
str= "";
}
else if(tmp==null)
{
break;
}
else
{
if(str.isEmpty())
{
str = tmp;
}
else
{
str += "\\n" + tmp;
}
}
}
Might be what you are trying to parse.
Where allStrings is a list of all of your strings.

The below code would work even if there are more than 2 empty lines between useful data.
import java.util.regex.*;
// read your file and store it in a string named str_file_data
Pattern p = Pattern.compile("\\n[\\n]+"); /*if your text file has \r\n as the newline character then use Pattern p = Pattern.compile("\\r\\n[\\r\\n]+");*/
String[] result = p.split(str_file_data);
(I did not test the code so there could be typos.)

I would suggest more general regexp:
text.split("(?m)^\\s*$");
In this case it would work correctly on any end-of-line convention, and also would treat the same empty and blank-space-only lines.

It may depend on how the file is encoded, so I would likely do the following:
String.split("(\\n\\r|\\n|\\r){2}");
Some text files encode newlines as "\n\r" while others may be simply "\n". Two new lines in a row means you have an empty line.

Godwin was on the right track, but I think we can make this work a bit better. Using the '[ ]' in regx is an or, so in his example if you had a \r\n that would just be a new line not an empty line. The regular expression would split it on both the \r and the \n, and I believe in the example we were looking for an empty line which would require a either a \n\r\n\r, a \r\n\r\n, a \n\r\r\n, a \r\n\n\r, or a \n\n or a \r\r
So first we want to look for either \n\r or \r\n twice, with any combination of the two being possible.
String.split(((\\n\\r)|(\\r\\n)){2}));
next we need to look for \r without a \n after it
String.split(\\r{2});
lastly, lets do the same for \n
String.split(\\n{2});
And all together that should be
String.split("((\\n\\r)|(\\r\\n)){2}|(\\r){2}|(\\n){2}");
Note, this works only on the very specific example of using new lines and character returns. I in ruby you can do the following which would encompass more cases. I don't know if there is an equivalent in Java.
.match($^$)

#Kevin code works fine and as he mentioned that the code was not tested, here are the 3 changes required:
1.The if check for (tmp==null) should come first, otherwise there will be a null pointer exception.
2.This code leaves out the last set of lines being added to the ArrayList. To make sure the last one gets added, we have to include this code after the while loop: if(!str.isEmpty()) { allStrings.add(str); }
3.The line str += "\n" + tmp; should be changed to use \n instead if \\n. Please see the end of this thread, I have added the entire code so that it can help
BufferedReader in
= new BufferedReader(new FileReader("foo.txt"));
List<String> allStrings = new ArrayList<String>();
String str ="";
List<String> allStrings = new ArrayList<String>();
String str ="";
while(true)
{
String tmp = in.readLine();
if(tmp==null)
{
break;
}else if(tmp.isEmpty())
{
if(!str.isEmpty())
{
allStrings.add(str);
}
str= "";
}else
{
if(str.isEmpty())
{
str = tmp;
}
else
{
str += "\n" + tmp;
}
}
}
if(!str.isEmpty())
{
allStrings.add(str);
}