If I have a file like this, in which each section is delimited by "**". How can I read each section and put them into different data structures?
AAA
BBB
CCC
**
ccc:cc
ddd:dd
**
xyz;XYZ
abc;ABC
**
Name: John
Email: john#gmail.com
Name: Jack
Email: jack#gmail.com
Name: kate
Email: kake#hotmail.com
**
In a while loop, I can test whether the line equals "**". But since the number of lines in each section is unknown, it seems hard to recognize which section a particular line belongs to?
String line;
while((line=reader.readline()) != null){
if(!line.equals("**"){
// the line has to be parsed and built into different data structures.
For the first section, AAA,BBB,CCC will be added into an ArrayList.
}
}
IMO you should just make the reading method a little bit more clever.
Here is an example (a kind of pseudo code, assuming you have a reader that does an actual IO):
void main() {
List<List<String>> sections = ...
while(reader.hasMoreDataToProcess()) {
sections.add(processSection(reader));
}
}
List<String> processSection(reader) {
List<String> section = ...
do {
String line = reader.readLine();
if(line.equals("**")) { // end of section or whatever delimiter you have
return section;
}
section.addLine(line);
}while(true);
}
Sorry, in a hurry, so pseudocode:
currentSection = []
sections = [currentSection]
for each line:
if line is the separator:
currentSection = []
add currentSection to sections
else:
add line to currentSection
You can use split method of the string class in Java.
String string = "a-b,b-d,c-s,d-w,e-e,f-e";
String[] parts = string.split(",");
String part1 = parts[0]; // a-b
String part2 = parts[1]; // b-d
You should use scanner for this scenario. Here's how you do it. This code is not tested.
File file = new File("somefile.txt");
try {
Scanner sc = new Scanner(file);
sc.useDelimeter("\\*\\*");
while (sc.hasNext()) {
String s = sc.next();
}
sc.close();
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
You can use a Scanner with a FileInputStream to scan the file, using setDelimiter(String) (which accepts a regex pattern) to set your delimiter.
public class Test {
public static void main(String[] args) {
ArrayList<String> firstList = new ArrayList<>();
ArrayList<String> secondList = new ArrayList<>();
try(Scanner scanner = new Scanner(new FileInputStream(new File("yourFile.txt"))).useDelimiter("[*]+")) {
firstList.add(scanner.next());
secondList.add(scanner.next());
// and so on
scanner.close();
} catch(FileNotFoundException e) {
e.printStackTrace();
}
}
}
This will take everything above ** and create a String out of it. If you want, you can then split the String, and grab the data from each line.
String[] split = scanner.next().split("\n");
for(String string : split) {
firstList.add(string);
}
In the first example, the regex [*]+ searches for multiple *. Learn more about regex (regular expressions) to add flexibility.
Related
Okay So I am creating an application but I'm not sure how to get certain parts of the string. I have read In a file as such:
*tp*|21394398437984|163600
*2*|AAA|1234567894561236|STOP|20140527|Success||Automated|DSPRN1234567
*2*|AAA|1234567894561237|STOP|20140527|Success||Automated|DPSRN1234568
*3*|2
I need to read the lines beginning with 2 so I done:
s = new Scanner(new BufferedReader(new FileReader("example.dat")));
while (s.hasNext()) {
String str1 = s.nextLine ();
if(str1.startsWith("*2*")) {
System.out.print(str1);
}
}
So this will read the whole line I'm fine with that, Now my issue is I need to extract the 2nd line beginning with numbers the 4th with numbers the 5th with success and the 7th(DPSRN).
I was thinking about using a String delimiter with | as the delimiter but I'm not sure where to go after this any help would be great.
You should use String.split("|"), it will give you an array - String[]
Try following:
String test="*2*|AAA|1234567894561236|STOP|20140527|Success||Automated|DSPRN1234567";
String tok[]=test.split("\\|");
for(String s:tok){
System.out.println(s);
}
Output :
*2*
AAA
1234567894561236
STOP
20140527
Success
Automated
DSPRN1234567
What you require will be placed at tok[2], tok[4], tok[5] and tok[8].
Just split the returned line based on your search, which would return an array of String elements where you can retrieve your elements based on their index:
s = new Scanner(new BufferedReader(new FileReader("example.dat")));
String searchLine = "";
while (s.hasNext()) {
searchLine = s.nextLine();
if(searchLine.startsWith("*2*")) {
break;
}
}
String[] strs = searchLine.split("|");
String secondArgument = strs[2];
String forthArgument = strs[4];
String fifthArgument = strs[5];
String seventhArgument = strs[7];
System.out.println(secondArgument);
System.out.println(forthArgument);
System.out.println(fifthArgument);
System.out.println(seventhArgument);
I have a text file with content that looks like this:
Event=ThermostatNight,time=0
Event=LightOn,time=2000
Event=WaterOff,time=8000
Event=ThermostatDay,time=10000
Event=Bell,time=9000,rings=5
Event=WaterOn,time=6000
Event=LightOff,time=4000
Event=Terminate,time=12000
I have to use a Scanner to grab the file and then loop through each of the lines of text and isolate each event. For example I need to isolate "ThermostatNight" in the first line and then put it in an array, the next one would be "LightOn", and so on. It's a small piece of a large project that I am working on for an intermediate Java course. I have been able to get exactly the opposite of what I want with the useDelimiter argument shown below. Is there a quick fix to this. Note that I must use the useDelimiter() method.
public void readFile2() {
array2 = new ArrayList<String>();
while (s.hasNext()) {
s.useDelimiter("=(.*?),");
array2.add(s.next());
}
You can use multiples delimiter.
//scanner.useDelimiter("Event=|,time=([0-9]*)");
scanner.useDelimiter("Event=|,(.)+[\\r\\n]*Event=|,(.)+[\\r\\n]*");
//for better you can use this
//scanner.useDelimiter("Event=|,time=([0-9]**)[\\r\\n]**Event=|,time=([0-9]*)");
while (scanner.hasNext())
{
System.out.println(scanner.next());
}
Probably not the best , but it will work
Since you have requirement to use only useDelimeter and if the structure not changed.
then
public static void main(String[] args) {
Scanner sc;
try {
sc = new Scanner(new File("/home/xxx/text.txt"));
sc.useDelimiter(",time=(.*?)\\nEvent=");
ArrayList<String> eventlist = new ArrayList<String>();
String tmp = null;
if (sc.hasNext()) {
tmp = sc.next();
tmp = tmp.split("=")[1]; // Just First line
}
while (sc.hasNext()) {
eventlist.add(tmp);
System.out.println(tmp); // for test only remove it
tmp = sc.next();
}
tmp = tmp.split(",")[0];
eventlist.add(tmp);
System.out.println(tmp); // for test only , remove it
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
I dont have alot of experience working with files. I have a file. I have written the following to the file
Test 112
help 456
news 456
Friendly 554
fileOUT.write("Test 112\r\n");//this is a example of how I entered the data.
Now I am trying to search in the file for the word news and display all the content that is in that line that contains the word news.
This is what I have attempted.
if(fileIN.next().contains("news")){
System.out.println("kkk");
}
This does not work. The folowing does find a word news because it displays KKK but I dont have an Idea how to display only the line that it news was found in.
while(fileIN.hasNext()){
if(fileIN.next().contains("Play")){
System.out.println("kkk");
}
}
What must be displayed is news 456.
Thank You
You want to call fileIN.nextLine().contains("news")
Try using the Scanner class if you are not already. It does a wonderful job of splitting input from a stream by some delineator (in this case the new line character.)
Here's a simple code example:
String pathToFile = "data.txt";
String textToSearchFor = "news";
Scanner scanner = new Scanner(pathToFile);
while(scanner.hasNextLine()){
String line = scanner.nextLine();
if(line.contains(textToSearchFor)){
System.out.println(line);
}
}
scanner.close();
And here's an advanced code example that does much more than you asked. Enjoy!
//Search file for an array of strings. Ignores case if caseSensitive is false.
public void searchFile(String file, boolean caseSensitive, String...textToSearchFor){
Scanner scanner = new Scanner(file);
while(scanner.hasNextLine()){
String originalLine = scanner.nextLine();
String line = originalLine;
if(!caseSensitive) line = line.toLowerCase();
for(String searchText : textToSearchFor){
if(!caseSensitive) searchText = searchText.toLowerCase();
if(line.contains(searchText)){
System.out.println(originalLine);
break;
}
}
}
scanner.close();
}
//usage
searchFile("data.txt",true,"news","Test","bob");
searchFile("data.txt",true,new String[]{"test","News"});
you can try this code...:D
String s = null;
File file = new File(path);
BufferedReader in;
try {
in = new BufferedReader(new FileReader(file));
while (in.ready()) {
s = in.readLine();
if(s.contains("news")){
//print something
}
}
in.close();
} catch (Exception e) {
}
I'm trying to read in from two files and store them in two separate arraylists. The files consist of words which are either alone on a line or multiple words on a line separated by commas.
I read each file with the following code (not complete):
ArrayList<String> temp = new ArrayList<>();
FileInputStream fis;
fis = new FileInputStream(fileName);
Scanner scan = new Scanner(fis);
while (scan.hasNextLine()) {
Scanner input = new Scanner(scan.nextLine());
input.useDelimiter(",");
while (scan.hasNext()) {
String md5 = scan.next();
temp.add(md5);
}
}
scan.close();
return temp;
Each file contains almost 1 million words (I don't know the exact number), so I'm not entirely sure that the above code works correctly - but it seems to.
I now want to find out how many words are exclusive to the first file/arraylist. To do so I planned on using list1.removeAll(list2) and then checking the size of list1 - but for some reason this is not working. The code:
public static ArrayList differentWords(String fileName1, String fileName2) {
ArrayList<String> file1 = readFile(fileName1);
ArrayList<String> file2 = readFile(fileName2);
file1.removeAll(file2);
return file1;
}
My main method contains a few different calls and everything works fine until I reach the above code, which just causes the program to hang (in netbeans it's just "running").
Any idea why this is happening?
You are not using input in
while (scan.hasNextLine()) {
Scanner input = new Scanner(scan.nextLine());
input.useDelimiter(",");
while (scan.hasNext()) {
String md5 = scan.next();
temp.add(md5);
}
}
I think you meant to do this:
while (scan.hasNextLine()) {
Scanner input = new Scanner(scan.nextLine());
input.useDelimiter(",");
while (input.hasNext()) {
String md5 = input.next();
temp.add(md5);
}
}
but that said you should look into String#split() that will probably save you some time:
while (scan.hasNextLine()) {
String line = scan.nextLine();
String[] tokens = line.split(",");
for (String token: tokens) {
temp.add(token);
}
}
try this :
for(String s1 : file1){
for(String s2 : file2){
if(s1.equals(s2)){file1.remove(s1))}
}
}
So I can search for a string in my text file, however, I wanted to sort data within this ArrayList and implement an algorithm. Is it possible to read from a text file and the values [Strings] within the text file be stored in a String[] Array.
Also is it possible to separate the Strings? So instead of my Array having:
[Alice was beginning to get very tired of sitting by her sister on the, bank, and of having nothing to do:]
is it possible to an array as:
["Alice", "was" "beginning" "to" "get"...]
.
public static void main(String[]args) throws IOException
{
Scanner scan = new Scanner(System.in);
String stringSearch = scan.nextLine();
BufferedReader reader = new BufferedReader(new FileReader("File1.txt"));
List<String> words = new ArrayList<String>();
String line;
while ((line = reader.readLine()) != null) {
words.add(line);
}
for(String sLine : words)
{
if (sLine.contains(stringSearch))
{
int index = words.indexOf(sLine);
System.out.println("Got a match at line " + index);
}
}
//Collections.sort(words);
//for (String str: words)
// System.out.println(str);
int size = words.size();
System.out.println("There are " + size + " Lines of text in this text file.");
reader.close();
System.out.println(words);
}
To split a line into an array of words, use this:
String words = sentence.split("[^\\w']+");
The regex [^\w'] means "not a word char or an apostrophe"
This will capture words with embedded apostrophes like "can't" and skip over all punctuation.
Edit:
A comment has raised the edge case of parsing a quoted word such as 'this' as this.
Here's the solution for that - you have to first remove wrapping quotes:
String[] words = input.replaceAll("(^|\\s)'([\\w']+)'(\\s|$)", "$1$2$3").split("[^\\w']+");
Here's some test code with edge and corner cases:
public static void main(String[] args) throws Exception {
String input = "'I', ie \"me\", can't extract 'can't' or 'can't'";
String[] words = input.replaceAll("(^|[^\\w'])'([\\w']+)'([^\\w']|$)", "$1$2$3").split("[^\\w']+");
System.out.println(Arrays.toString(words));
}
Output:
[I, ie, me, can't, extract, can't, or, can't]
Also is it possible to separate the Strings?
Yes, You can split string by using this for white spaces.
String[] strSplit;
String str = "This is test for split";
strSplit = str.split("[\\s,;!?\"]+");
See String API
Moreover you can also read a text file word by word.
Scanner scan = null;
try {
scan = new Scanner(new BufferedReader(new FileReader("Your File Path")));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
while(scan.hasNext()){
System.out.println( scan.next() );
}
See Scanner API