Develop Reference

BufferedReader saving sentence, String array, then 2D int array

I have a .txt file that contains text that I would like to save part of it in a String, part of it in a String array, and then the last part in a 2D int array, and am faced with two issues:
How to read and save both of the arrays when their size is not known ahead of time?
2D array is not reading/saving properly
Here is the text file for reference:
This is the sentence to be read.
This
is
a
String
array.
90 47 110 95 95
101 87
54 0 38 12
Here is part of my method that is supposed to read and save the three data types:
BufferedReader br = new BufferedReader(new FileReader(fileName));
sentence = br.readLine();
stringArr = new String[5]; //how to initialize without set number of elements?
for(int i = 0; i<stringArr.length; i++){
stringArr[i] = br.readLine();
}
int2DArr = new int[3][5]; //how to initialize with any amount of rows and columns?
for(int i = 0; i<int2DArr.length; i++){
for(int j = 0; j<int2DArr[i].length; j++){
int2DArr[i][j] = br.read();
//how to read the space after each int ?
}
}
How would I "grab" the size of the arrays by reading the text file, so that when I initialize both arrays, I have the proper sizes? Any help would be greatly appreciated!

Instead of trying to achieve everything in a single pass we can pass through the file twice and obtain a neater code.
It will consume double time of course but it is going to help you understand how you could break bigger problems into smaller ones and deal with them one by one.
Here are the steps:
Determine size of stringArr and intArr in first pass
Fill value in respective array in second pass
If you are wondering how no of columns for int2DArr is determine. Simply we don't do it our self. We use the concept of Jagged Arrays
Read more here How do I create a jagged 2d array in Java?
import java.util.*;
import java.io.*;
class ReadFileIntoArr {
public static void main(String args[]) throws IOException {
String fileName = "test.txt";
BufferedReader br = new BufferedReader(new FileReader(fileName));
String line = br.readLine();
int strSize = 0;
int intSize = 0;
boolean isDigit = false;
while (line != null && line.trim().length() != 0) {
if (!isDigit && Character.isDigit(line.charAt(0)))
isDigit = true;
if (isDigit)
intSize++;
else
strSize++;
line = br.readLine();
}
br = new BufferedReader(new FileReader(fileName));
String[] stringArr = new String[strSize];
for (int i = 0; i < stringArr.length; i++)
stringArr[i] = br.readLine();
int[][] int2DArr = new int[intSize][];
for (int i = 0; i < int2DArr.length; i++)
int2DArr[i] = Arrays.stream(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
System.out.println(Arrays.toString(stringArr));
System.out.println(Arrays.deepToString(int2DArr));
}
}
Note: In single pass this could be accomplished with the help of ArrayList and later transfer everything into respective array.
Update: After understanding the constraints for your problem here is another version
import java.util.*;
import java.io.*;
class ReadFileIntoArr {
public static void main(String args[]) throws IOException {
String fileName = "test.txt";
BufferedReader br = new BufferedReader(new FileReader(fileName));
String line = br.readLine();
int strSize = 0;
int intSize = 0;
boolean isDigit = false;
while (line != null && line.trim().length() != 0) {
if (!isDigit && isDigit(line.charAt(0)))
isDigit = true;
if (isDigit)
intSize++;
else
strSize++;
line = br.readLine();
}
br = new BufferedReader(new FileReader(fileName));
String[] stringArr = new String[strSize];
for (int i = 0; i < stringArr.length; i++)
stringArr[i] = br.readLine();
int[][] int2DArr = new int[intSize][];
for (int i = 0; i < int2DArr.length; i++)
int2DArr[i] = convertStringArrToIntArr(br.readLine().split(" "));
System.out.println(Arrays.toString(stringArr));
System.out.println(Arrays.deepToString(int2DArr));
}
public static boolean isDigit(char c) {
return c >= '0' && c <= '9';
}
public static int[] convertStringArrToIntArr(String[] strArr) {
int[] intArr = new int[strArr.length];
for (int i = 0; i < strArr.length; i++)
intArr[i] = Integer.parseInt(strArr[i]);
return intArr;
}
}

Path path = Paths.get(fileName);
List<String> lines = Files.readAllLines(path, Charset.defaultCharset());
String title = lines.get(0);
List<String> words = new ArrayList<>();
for (int i = 1; i < lines.size(); ++i) {
String word = lines.get(i);
if (!word.isEmpty() && Character.isDigit(word.codePointAt(0)) {
break;
}
words.add(word);
}
String[] wordArray = words.toArray(new String[]);
int i0 = 1 + words.size();
int n = lines.size() - i0;
int[][] numbers = new int[n][];
for (int i = i0; i < lines.size(); ++i) {
String[] values = lines.get(i).trim().split("\\s+");
int m = values.length;
int[] row = new int[m];
for (int j = 0; j < m; ++m) {
row[j] = Integer.parse(values[j]);
}
numbers[i - i0] = row;
}
Path is a generalisation of File, also URLs.
Files is a treasure trove of file functions.
One could do without dynamically sized List; one would need to test first,
but normally one would use a List anyhow.
String.split splits on one or more whitespace.

Split a text file into blocks

I need to read a text file, and break the text into blocks of 6 characters (including spaces), pad zeroes to the end of text to meet the requirement.
I tried doing it and here is what I have done.
File file = new File("Sample.txt");
String line;
try {
Scanner sc = new Scanner(file);
while(sc.hasNext()){
line = sc.next();
int chunk = line.length();
int block_size=6;
if((chunk%block_size) != 0)
{
StringBuilder sb = new StringBuilder(line);
int val = chunk%block_size;
for(int i=0; i<val; i++){
sb.append(" ");
}
line = new String(sb.toString());
}
int group = line.length() / block_size;
String[] b = new String[group];
System.out.println(line);
System.out.println(chunk);
int j =0;
for(int i=0; i<group;i++){
b[i] = line.substring(j,j+block_size);
j += block_size;
}
System.out.println("String after spliting is: ");
for(int i=0; i<group;i++){
System.out.println(b[i]);
}
}
}
Now this works fine when the text in the input file has no spaces between words. But when I add spaces gives me a different output. I am stuck up at this point. Any suggestions on the same ?

I don't want to write the solution for you, but I'd advise you that what you're trying to accomplish might be easier to do using a BufferedReader with a FileReader and by using Reader.read(buf) where buf is a char[6];

java 2D array from text file

I am trying to make this input.txt into a 2D array. I tried a few different methods. This is my latest attempt, and I seem to be stuck here... Any help is much appreciated.
input.txt structure: SCI2000/Science/1200/10/C --> There are 23 rows and 5 columns. I'd also like to have a title made for each column.
FileReader fr = new FileReader("input.txt");
BufferedReader br = new BufferedReader(fr);
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
sb.append(System.lineSeparator());
line = br.readLine();
}
String everything = sb.toString();
String[][] input = new String[23][5];
String[] tokens = everything.split("/");
for(String str : tokens)
System.out.print(str);

Just the main processing part (not tested):
int columns = 5;
String[] row = String[columns];
int j = 0;
while ((line = br.readline) != null) {
row = line.split("/");
for(int i=0; i<row.length; ++i) {
input[j,i] = row(i);
}
++j;
}

FileReader fr = new FileReader("input.txt");
BufferedReader br = new BufferedReader(fr);
String[][] input = new String[24][5]; // 1 row for title, 23 rows for data
// add title
input[0] = new String[]{"title1", "title1", "title1", "title1", "title1"};
String line = br.readLine();
int row = 1; // update here
while ( (line = br.readLine())!= null ) {
input[row++] = line.split("/");
}
// print all data
for ( int i = 0; i < input.length; i++) {
for ( int j = 0; j < input[i].length; j++ )
System.out.print(input[i][j] + " ");
//new line
System.out.println();
}

ArrayIndexOutOfBoundsException - when parsing a csv file

I want to transform a csv file. My file looks like that:
I am using the opencsv libary to parse my csv. That is my run method to parse the file:
public void run() throws Exception {
CSVReader reader = new CSVReader(new FileReader(csvFile), ';');
String [] nextLine;
int i = -1;
String fileName = "";
String companyName = "";
String currency = "";
String writerPath;
List<String> returnList = null;
List<String> dateList = null;
while ((nextLine = reader.readNext()) != null && i < 10) {
String[] line = nextLine;
System.out.println(line[0]);
System.out.println(line);
i++;
//fileName of the String
if(!line[0].contains("NULL")) {
fileName = line[0];
}
writerPath = "C:\\Users\\Desktop\\CSVOutput\\" + fileName + ".csv";
//write csv file
CSVWriter writer = new CSVWriter(new FileWriter(writerPath), ';');
//write Header
String[] entries = "Name;Date;TotalReturn;Currency".split(";");
writer.writeNext(entries);
//create Content
//companyName of the String
if(!line[1].contains("Name")) {
companyName = line[1];
System.out.println(companyName);
}
//currency
if(!line[2].contains("CURRENCY")) {
currency = line[2];
}
//total returns
returnList = new ArrayList<String>();
if(line[0].contains("NULL")) {
for(int j = 3; j <= line.length; j++) {
returnList.add(line[j]); // EXCPETION COMES HERE!
}
}
//"Name;Date;TotalReturn;Currency"
List<String[]> data = new ArrayList<String[]>();
for(int m = 0; m <= line.length; m++) {
data.add(new String[] {companyName, "lolo", "hereComesTheDateLater", currency});
}
writer.writeAll(data);
//close Writer
writer.close();
}
System.out.println("Done");
}
}
I am getting an
java.lang.ArrayIndexOutOfBoundsException: 3039
at com.TransformCSV.main.ParseCSV.run(ParseCSV.java:78)
at com.TransformCSV.main.ParseCSV.main(ParseCSV.java:20)
at this line: returnList.add(line[j]);?
Why? What are possible ways to fix that?
I really appreciate your answer!

You want j < line.length and not <=. If there are 10 elements in an Array then there is not an item at index 10 - you only have 0-9.
Further using loads of variables and assigning them is not the preferred way to parse CSV. Java is an Object Orientated language.
Use an Object to represent each line and bind the line using the opencsv javabean API

You are parsing the file till length of file <= instead you have to use <. It will access the file till line.length - 1
Replace with this
for(int j = 3; j <line.length; j++) {
returnList.add(line[j]);
}

Stdin reading multiple lines

I have the following code:
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
String submittedString = "";
System.out.flush();
submittedString = stdin.readLine();
int numberofLines = Integer.parseInt(submittedString.split(" ")[0]);
for(int i = 0; i < numberofLines; i++)
submittedString += stdin.readLine();
zipfpuzzle mySolver = new zipfpuzzle();
mySolver.getTopSongs(submittedString);
However, despite the input being over multiple lines, this only reads the first.
Where is my mistake?
If it makes any difference, I am compiling on eclipse.
Cheers!
Dario

Just use an array and populate it within your for-loop:
String[] inputs = new String[numberofLines];
for (int i = 0; i < numberofLines; i++)
inputs[i] = stdin.readLine();
Extra Note:
If you want multiple lines with single String:
String submittedString = "";
for (int i = 0; i < numberofLines; i++)
submittedString += stdin.readLine() + System.getProperty("line.separator");

BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
String line = "";
while ((line = stdin.readLine()) != null){
// Do something.
submittedString += line + '\n';
}

submittedString = stdin.readLine();
BufferedReaders readLine method will read System.in until it hits a new line, therefore if you're using the first line of the file to determine the number of lines to read then your data must be incorrect.