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How can I get a specific value from txt file in java?

I have two .txt files:
mothers.txt (IdNum, name, age) for example : 6, Emily, 34
children.txt (num, sex(boy/girl), name, dateOfBirth, weight, height, IdnumOfMother) for example : 1 b Jackson 1999-10-15 3450 55 6
The only thing I can do is to write them all by String[].
String child = "children.txt";
BufferedReader reader = null;
String line = "";
reader = new BufferedReader(new FileReader(child));
while ((line = reader.readLine()) != null){
String[] row = line.split(",");
for (String x : row){
System.out.printf("%-10s", x );
}
System.out.println();
}
reader.close();
I have to find the tallest boy, the heaviest girl, the day when most children were born
Can you help me? It's my first time with .txt files.
Thank you in advance.

Your problem requires searching files according to different conditions to get the desired attribute values. Using Java to code the task is narrowly applicable.
It is convenient to get this done using SPL, Java’s open-source package. SPL only needs a few lines of code:
|　|A|
|:-|:-|
|1|=file("children.txt").import#ct()|
|2|=A1.select(sex=="b").maxp#a(height).(dateOfBirth)|
|3|=A1.select(sex=="g").maxp#a(weight).(dateOfBirth)|
|4|return A2,A3|
SPL offers JDBC driver to be invoked by Java. Just store the above SPL script as spicify.splx and invoke it in Java as you call a stored procedure:
…
Class.forName("com.esproc.jdbc.InternalDriver");
con = DriverManager.getConnection("jdbc:esproc:local://");
st = con.prepareCall("call spicify()");
st.execute();
…
You can also use SPL to conveniently associate two files by foreign key. To find the age of the tallest baby boy’s mother and the age of the heaviest baby girl’s mother, for example, SPL has the following code:
|　|A|
|:-|:-|
|1|=file("mothers.txt").import#ct()|
|2|=file("children.txt").import#ct().switch(IdnumOfMother,A1:IdNum)|
|3|=A2.select(sex=="b").maxp#a(height).(IdnumOfMother.age)|
|4|=A2.select(sex=="g").maxp#a(weight).(IdnumOfMother.age)|
|5|return A3,A4|
View SPL source code.

How do I extract variable data from a line of string with tags?

I'm trying to write Java code to go to a website, read the HTML code line-by-line, extract certain pieces of data, including an embedded URL to go to another website, and repeat the process 100 times.
I've been able to isolate most of the pieces of data I need using expressions like:
s.ranking = line.substring(line.indexOf(">")+1, line.length() -7);
But I'm having problems with the following line:
<strong>Writer:</strong> Dylan <br/><strong>Producer:</strong> Tom Wilson&nbsp <br/><strong>Released:</strong> July '65, Columbia<br/>12 weeks; No. 2</p>
I need to extract and save the Writer data (Dylan). The producer data (Tom Wilson) and the Release date data (July '65). Some of the pages will have multiple writers and will be labeled "Writers:", and some will have multiple producers, labeled "Producers:"
How do I capture "Dylan" ,"Tom Wilson" and "July '65" from the above line in Java?
Thank you very much!
DM

The best approach is to use HTML parser. But as i read your comment " I'm doing this for a class and am learning about finding, isolating and extracting data."
What you can do something like :
String producer = "Producer:";
String writer = "Writer:";
String released = "Released:";
String s = "<strong>Writer:</strong> Dylan <br/><strong>Producer:</strong> Tom Wilson&nbsp <br/><strong>Released:</strong> July '65, Columbia<br/>12 weeks; No. 2</p> ";
int writerIndex = s.lastIndexOf(writer);
int producerIndex = s.lastIndexOf(producer);
int realesedIndex = s.lastIndexOf(released);
String writerExtracted = s.substring(writerIndex + writer.length(),
producerIndex).replaceAll("\\<.*?>", "");
System.out.println(writerExtracted);
String producerExtracted = s.substring(
producerIndex + producer.length(), realesedIndex).replaceAll(
"\\<.*?>", "");
System.out.println(producerExtracted);
String releasedExtracted = s.substring(
realesedIndex + released.length(), s.length()).replaceAll(
"\\<.*?>", "");
System.out.println(releasedExtracted);
Output:
Dylan
Tom Wilson&nbsp
July '65, Columbia12 weeks; No. 2
NOTE: you can get rid of signs such as &#039 or &nbsp using another regex ...

using java select city and country from a given string that contains full address

I am writing a code in which I want user to provide a string of unknown length.. suppose he provided a string.. now I want to get city and country present in that string...
If anybody have any better idea, please share..

As your requirement, you have to build a case where you need to defined all the possibility city or country like Array city= new Array["America","England","China","Myanmar"]; after that now loop your array then read the user defined line from index 0 and each time move your character point +1(do in a loop too)(convert it in String) then search your city pattern to match with the character(String). Your program complexity will increase more and more due to your requirement, I think your complexity will raise up to O(n*n), it is not good for memory.
On my view of point, you should ask from user to get the actual requirement step by step like (Enter City :_ then Enter Country :__) it is better to handle the string.GOOD LUCK!

In the question you never specified the format of the input string but assuming the format is "city, country" then this works
String s = "the name of a city, the name of a country";
String city = s.substring(0, s.indexOf(", "));
String country = s.substring(s.indexOf(", ") + 2);
System.out.println("City = " + city);
System.out.println("Country = " + country);

Well, your questions are very interesting. The program you are writing now is depending on LOGIC and I think there is no such jar files available to get solution on it. It is better to get solution manually. Did you ever think about Dictionary program. Mostly Dictionary words are written in a text file and at run time, the program load that words into an array or some other Collections. This way you can also Load Your file at runtime into a 2D array or collection(mostly HashMap is used). So you can scan your file and load it.Suppose u want to read
Example:
Agra,India
London,England
Yangon,Myanmar
Tokyo,Japan
etc...
` String line;
FileInputStream fstream = new FileInputStream(dataFile);
//dataFile is your file directory
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
HashMap<String,String> divideCityCountry =new HashMap<String,String>();
while((line=br.readLine())!=-1)
{
String[] lineSplit = line.split(",");//use the ',' as delimiter
divideCityCountry.put(lineSplit[0], lineSplit[1]);
} `
Now you can check or get the city and country in the divideCityCountry HashMap().
Hope this may helpful.Good Luck!

error during grouping files based on the date field

I have a large file which has 10,000 rows and each row has a date appended at the end. All the fields in a row are tab separated. There are 10 dates available and those 10 dates have randomly been assigned to all the 10,000 rows. I am now writing a java code to write all those rows with the same date into a separate file where each file has the corresponding rows with that date.
I am trying to do it using string manipulations, but when I am trying to sort the rows based on date, I am getting an error while mentioning the date and the error says the literal is out of range. Here is the code that I used. Please have a look at it let me know if this is the right approach, if not, kindly suggest a better approach. I tried changing the datatype to Long, but still the same error. The row in the file looks something like this:
Each field is tab separated and the fields are:
business id, category, city, biz.name, longitude, state, latitude, type, date
**
qarobAbxGSHI7ygf1f7a_Q ["Sandwiches","Restaurants"] Gilbert Jersey
Mike's Subs -111.8120071 AZ 3.5 33.3788385 business 06012010
**
The code is:
File f=new File(fn);
if(f.exists() && f.length()>0)
{
BufferedReader br=new BufferedReader(new FileReader(fn));
BufferedWriter bw = new BufferedWriter(new FileWriter("FilteredDate.txt"));
String s=null;
while((s=br.readLine())!=null){
String[] st=s.split("\t");
if(Integer.parseInt(st[13])==06012010){
Thanks a lot for your time..

Try this,
List<String> sampleList = new ArrayList<String>();
sampleList.add("06012012");
sampleList.add("06012013");
sampleList.add("06012014");
sampleList.add("06012015");
//
//
String[] sampleArray = s.split(" ");
if (sampleArray != null)
{
String sample = sampleArray[sampleArray.length - 1];
if (sampleList.contains(sample))
{
stringBuilder.append(sample + "\n");
}
}

i suggest not to use split, but rather use
String str = s.subtring(s.lastIndexOf('\t'));
in any case, you try to take st[13] when i see you only have 9 columns. might be you just need st[8]
one last thing, look at this post to learn what 06012010 really means

java explode a line/string like php explode

I'm making a java program that would run on a local server.
Server takes request from client using PHP .
<?php
$file = fopen('temp.txt', 'a+');
$a=explode(':',$_GET['content']);
fwrite($file,$a[0].':'.$a[1]. '\n');
fclose($file);
?>
Now I have file "temp.txt" on local server.
Java Program should open the file read line by line and each like should be divided/exploded ":" (In a line there's only one ':' )
I have tried in many ways, but could not get exactly like how PHP splits the line.
Is it possible to use same/similar explode function in JAVA.

Yes, in Java you can use the String#split(String regex) method in order to split the value of a String object.
Update:
For example:
String arr = "name:password";
String[] split = arr.split(":");
System.out.println("Name = " + split[0]);
System.out.println("Password = " + split[1]);

You can use String.split in Java to "explode" each line with ":".
Edit
Example for a single line:
String line = "one:two:three";
String[] words = line.split(":");
for (String word: words) {
System.out.println(word);
}
Output:
one
two
three