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Trouble reading a file in java in a certain format

I am reading text from a file and I have been having trouble trying to read List 1 and List 2 into 2 different String . The * indicates where the first list ends. I have tried using arrays but the array only stores the last * symbol.
List 1
Name: Greg
Hobby 1: Swimming
Hobby 2: Football
*
List 2
Name: Bob
Hobby 1: Skydiving
*
Here's what I tried so far:
String s = "";
try{
Scanner scanner = new Scanner(new File("file.txt"));
while(scanner.hasnextLine()){
s = scanner.nextLine();
}
}catch(Exception e){
e.printStackTrace}
String [] array = s.split("*");
String x = array[0];
String y = array[1];

Your code has multiple issues like #Henry said that your string contains only the last line of the file and also you misunderstood the split() because it takes a RegularExpression as a parameter.
I would recommend you to use the following example because it works and is a lot faster than your approach.
Kick-Off example:
// create a buffered reader that reads from the file
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("test.txt")));
// create a new array to save the lists
ArrayList<String> lists = new ArrayList<>();
String list = ""; // initialize new empty list
String line; // initialize line variable
// read all lines until one becomes null (the end of the file)
while ((line = reader.readLine()) != null) {
// checks if the line only contains one *
if (line.matches("\\s*\\*\\s*")) {
// add the list to the array of lists
lists.add(list);
} else {
// add the current line to the list
list += line + "\r\n"; // add the line to the list plus a new line
}
}
Explanation
I'm going to explain special lines that are hard to understand again.
Looking at the first line:
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream("test.txt")));
This line creates a BufferedReader that is nearly the same like a Scanner but it's a lot faster and hasn't as much methods as a Scanner. For this usage the BufferedReader is more than enough.
Then it takes an InputStreamReader as a parameter in the constructor. This is only to convert the following FileInputStream to a Reader.
Why should one do that? That's because an InputStream ≠ Reader. An InputStream returns the raw values and a Reader converts it to human readable characters. See the difference between InputStream and Reader.
Looking at the next line:
ArrayList<String> lists = new ArrayList<>();
Creates a variable array that has methods like add() and get(index). See the difference of arrays and lists.
And the last one:
list += line + "\r\n";
This line adds the line to the current list and adds a new line to it.
"\r\n" Are special characters. \r ends the current line and \n creates a new line.
You could also only use \n but adding \r in front of it is better because this supports more Os's like Linux can have problems with it when \r misses.
Related
Using BufferedReader to read Text File

How can i read text file and store text values in data base in java? [duplicate]

This question already has answers here:
Reading a plain text file in Java
(31 answers)
Closed 5 years ago.
I have text file which i have read once user upload, how can i read using java code, can any one give some suggestion which would very helpful to me
sample file looks like below
SNR Name
1 AAR
2 BAT
3 VWE

A common pattern is to use
try (BufferedReader br = new BufferedReader(new FileReader(file)) ) {
String line;
while ((line = br.readLine()) != null) {
// process the line to insert in database.
}}

The easiest way is use Scanner() object
Scanner sc = new Scanner(new File("myFile.txt"));
use
boolean hasNext = sc.hasNext();
to know if there are more items in the file
and
String item = sc.next();
to get items secuentially.
I attach the documentation (it provides very good code examples)
https://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html

You can use BufferedReader to read file line by line.
So, even if your file is too big, then also it will read line by line only. It won't load entire file. Declaration will be similar to this.
BufferedReader br = new BufferedReader(new FileReader(FILENAME));
And
you can use command
while ((sCurrentLine = br.readLine()) != null) { .....// process
}
to read file till end.
Obviously, you have to use seperator in file to split the records in each line. And store accordingly in java objects.
After that you can store in DB through DAO.

complete indexing of text file java

im trying to read a text file, sort the words within alphabetically and display what line numbers those words appear on.
Im new to java so not sure what the most efficient way to approach the system is.
My plan so far is to:
-use a scanner to parse file into one string
-string.split
-lineCount++
-(somehow sort those split strings alphabetically)
-print sorted words with line number next to them
Is that the best way of going about this? im not sure if java has some sort of ordered dictionary maybe i could use?

A Scanner is fine, as you could scan per word, not even needing a split.
A BufferedReader would be for line-wise reading, and there exists a LineNumberReader for your goal: counting lines.
I head indicate the encoding of the file.
SortedMap<String, SortedSet<Integer>> linenosPerWord = new TreeMap<>();
// A BufferedReader with a linenumber counter:
try (LineNumberReader in = new LineNumberReader(new InputStreamReader(
new FileInputSTream(file, StandardCharsets.UTF_8))) {
for (;;) {
String line = in.readLine();
if (line == null) {
break;
}
int lineno = in.getLineNumber();
String[] words = line.split("\\P{LM}"); // Split on non-letters and non-accents
for (String word : words) {
word = word.toLowerCase(); // Possible with Locale
SortedSet<Integer> linenos = linenosPerWord.get(word);
if (linenos == null) {
linenos = new TreeSet<>();
linenosPerWord.put(word, lineno);
}
linenos.add(lineno);
}
}
}
linenosPerWord.remove(""); // Remove a possibly found empty word, like in "-Hello"

Java print a word from text file when user enters word number

I'm trying to write a Java application that reads a text file. Suppose I have a text file beg.txt which contains text:
I am a beginner
When the user enters word number 4, the program has to print word 'beginner'.
How can I do this in Java, please?

First give a try before asking this.
Just for your help. Try following steps, this is not the only way.
Read your file
Split string to a string array using space
Print array[your choice - 1]

BufferedReader br = null;
String[] str;
try {
String sCurrentLine;
StringBuilder sb = new StringBuilder();
br = new BufferedReader(new FileReader("C:\\testing.txt"));
while ((sCurrentLine = br.readLine()) != null) {
sb.append(sCurrentLine);
}
str = sb.toString.split(" ");
} catch (IOException e) {
e.printStackTrace();
}
if user enters 4 then you can use array 'str' like this :
String result = str[userEnteredValue - 1];
Note: the above code will work only when the file will contain space delimitted characters.

File read=new File("D:\\Test.txt");
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(read),Charset.forName("UTF-8")));
String news = reader.readLine();
String[] records = news.split(" ");
if your input is 4
and get records[4]

Well, the basic process will be something like the following:
Load the text file
Get user input
Process text file with parameters from user
Step 1 will depend on which version of Java you're using. If Java 7, I'd look at nio2. Java 6 has other options. Or you could you Guava or Apache Commons. Since the processing required is minimal, I would store the output of this step as a simple String.
Getting the user input can be done in a number of ways, but one option is to use a Scanner.
Finally, processing the file can be done by using String.split() with a simple regex and then picking the correct element from the resulting array.

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.