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Storing numbers with nested Lists java

I have a .txt file with the next format:
I need to storage that values in this way, at index 0 i need to have
[[154.5,0.0],[13.3333333333333, 102.0],[6,272.0],[10.3333333333333,1860.0]...
(there will be more pairs cause the second column in txt is not ordered, and there will be zeros again later)]. I hope that u understand my question, i think i need arraylist of arraylist of arraylist, i just need an idea, thanks.
This is the code:
String working_directory = System.getProperty("user.dir");
File file = new File(working_directory + "\\src\\" + filename);
BufferedReader br = new BufferedReader(new FileReader(file));
ArrayList<ArrayList<Double>> array_A = new ArrayList<ArrayList<Double>>();
ArrayList<Double> aux = new ArrayList<Double>();
aux.add((double)0);
aux.add((double)0);
for ( int i = 0 ; i < matrixSize; i ++ ) {
array_A.add(aux);
}
String[] elements_in_line = new String[3];
String line;
while ((line = br.readLine()) != null) {
ArrayList<Double> value_col_index = new ArrayList<Double>();
ArrayList<Double> pair = new ArrayList<Double>();
elements_in_line = line.split(", ");
double value = Double.parseDouble(elements_in_line[0]);
int line_index = Integer.parseInt(elements_in_line[1]);
int column_index = Integer.parseInt(elements_in_line[2]);
boolean already_exists = false;
if (array_A.get(line_index).size() > 0) {
pair = array_A.get(line_index);
for (int i = 0; i < pair.size(); i++) {
if (column_index == pair.get(1)) {
already_exists = true;
break;
}
}
}
if (already_exists) {
pair.set(0, pair.get(0) + value);
} else {
if (limit_line != 0) {
if (array_A.get(line_index).size() == limit_line) {
System.out.println("Dimension of matrix exceeded!");
System.exit(1);
}
}
array_A.set(line_index,new ArrayList<Double>(Arrays.asList(value,(double)column_index)));
}
}
return array_A;
}

How do I export the ArrayList to a CSV file

I have this code, it gets the average grade, but I need to export the arraylist Hell to a CSV file. How do I do this?
import java.util.*;
import java.io.*;
import java.io.PrintWriter;
import java.text.*;
public class hello3 {
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
System.out.printf("Please enter the name of the input file: ");
String input_name = in.next();
System.out.printf("Please enter the name of the output CSV file: ");
String csv_name = in.next();
System.out.printf("Please enter the name of the output pretty-print file: ");
String pretty_name = in.next();
processGrades(input_name, csv_name, pretty_name);
System.out.printf("\nExiting...\n");
}
public static void processGrades (String input_name, String csv_name, String pretty_name)
{
PrintWriter csv = null;
PrintWriter pretty = null;
String[][] data = readSpreadsheet(input_name);
boolean resultb = sanityCheck(data);
int length = data.length;
ArrayList<String> test_avg = new ArrayList<String>();
ArrayList<String> HW_avg = new ArrayList<String>();
ArrayList<String> NAME = new ArrayList<String>();
ArrayList<String> ColN = new ArrayList<String>();
ArrayList<String> Hell = new ArrayList<String>();
for(int row = 1; row<length; row++)
{
String name = data[row][0];
String name2 = data[row][1];
String Name = name+" "+name2;
int test1 = Integer.parseInt(data[row][2]);
int test2 = Integer.parseInt(data[row][3]);
int test3 = Integer.parseInt(data[row][4]);
int Test = (test1+test2+test3)/3;
String Testav = Integer.toString(Test);
int hw1 = Integer.parseInt(data[row][5]);
int hw2 = Integer.parseInt(data[row][6]);
int hw3 = Integer.parseInt(data[row][7]);
int hw4 = Integer.parseInt(data[row][8]);
int hw5 = Integer.parseInt(data[row][9]);
int hw6 = Integer.parseInt(data[row][10]);
int hw7 = Integer.parseInt(data[row][11]);
int HW = (hw1+hw2+hw3+hw4+hw5+hw6+hw7)/7;
int[] trying = {Test, HW};
int low = find_min(trying);
String grade = null;
if(low>=90)
{
grade ="A";
}
if(low < 90&& low>= 80)
{
grade = "B";
}
if(low <80&&low>=70)
{
grade ="C";
}
if(low<70&&low>=60)
{
grade="D";
}
if(low<60)
{
grade = "F";
}
String Lows = Integer.toString(low);
String HWav = Integer.toString(HW);
test_avg.add(Testav);
HW_avg.add(HWav);
NAME.add(Name);
Hell.add(Name);
Hell.add(Testav);
Hell.add(HWav);
Hell.add(Lows);
Hell.add(grade);
System.out.println(Hell);
System.out.printf("\n");
}
}
public static int find_min(int[] values)
{
int result = values[0];
for(int i = 0; i<values.length; i++)
{
if(values[i]<result)
{
result = values[i];
}
}
return result;
}
public static boolean sanityCheck(String[][] data)
{
if (data == null)
{
System.out.printf("Sanity check: nul data\n");
return false;
}
if(data.length<3)
{
System.out.printf("Sanity check: %d rows\n",data.length);
return false;
}
int cols= data[0].length;
for(int row = 0; row<data.length; row++)
{
int current_cols = data[row].length;
if(current_cols!=cols)
{
System.out.printf("Sanity Check: %d columns at rows%d\n", current_cols, row);
return false;
}
}
return true;
}
public static String[][] readSpreadsheet(String filename)
{
ArrayList<String> lines = readFile(filename);
if (lines == null)
{
return null;
}
int rows = lines.size();
String[][] result = new String[rows][];
for (int i = 0; i < rows; i++)
{
String line = lines.get(i);
String[] values = line.split(",");
result[i] = values;
}
return result;
}
public static ArrayList<String> readFile(String filename)
{
File temp = new File(filename);
Scanner input_file;
try
{
input_file = new Scanner(temp);
} catch (Exception e)
{
System.out.printf("Failed to open file %s\n",
filename);
return null;
}
ArrayList<String> result = new ArrayList<String>();
while (input_file.hasNextLine())
{
String line = input_file.nextLine();
result.add(line);
}
input_file.close();
return result;
}
}
Any help would be appreciated. thank you.

Broadly, you need to open a file with the name you require, and a writer in a loop - like this:
File csvFile = new File(csvName);
try (PrintWriter csvWriter = new PrintWriter(new FileWriter(csvFile));){
for(String item : list){
csvWriter.println(item);
}
} catch (IOException e) {
//Handle exception
e.printStackTrace();
}
Obviously you will have to print some commas as required

How do I create an Array or ArrayList with a looped, column of strings that contain integers?

I have tried so hard to find a solution to this problem! Here is my code:
import java.io.*;
import java.lang.reflect.Array;
import java.util.ArrayList;
public class Weather {
public static void main(String[] args) throws IOException {
//Getting the file.
String fileName = "weather2013.txt";
//Lines!
String line;
//Creating arrayList object
ArrayList aList = new ArrayList();
try {
BufferedReader input = new BufferedReader(new FileReader(fileName));
while ((line = input.readLine()) != null) {
aList.add(line);
}
//Close the file
input.close();
} catch (FileNotFoundException ex) {
System.out.println("File not found!");
}
//Station ID Number:
String firstLine = aList.get(1).toString();
String stationIDStr = firstLine.substring(0, 6);
int StationID = Integer.parseInt(stationIDStr);
//System.out.println(StationID);
//WBAN ID Number:
String wbanIDstr = firstLine.substring(7, 12);
int wbanID = Integer.parseInt(wbanIDstr);
//System.out.println(wbanID);
//Year!
String yearStr = firstLine.substring(12, 18).trim();
int year = Integer.parseInt(yearStr);
//System.out.println(year);
//Remove line of text (not needed)
aList.remove(0);
//Fog days:
int fogDays = 0;
for (int i = 0; i < aList.size(); i++) {
String listString = aList.get(i).toString(); //iterate each readLINE -> String
String lastDigits = listString.substring(132, 137); //Each entry from 132-137 only
char fogIndicator = lastDigits.charAt(0);
if (fogIndicator == '1') {
fogDays++;
}
}
//System.out.println(fogDays);
//Maximum and minimum average temps
for (int i = 0; i < aList.size(); i++) {
String listString = aList.get(i).toString();
String averageTempDigits = listString.substring(24, 30).trim();
}
}
}
The specific part of the code where I am having trouble is the VERY last for loop.
Here's what's being outputted:
47.9
41.8
.
.
.
.
41.8
67.0
66.5
I would like to know how to get this column above into an Array or ArrayList?

Searching in arraylist<String[]> from user input

I want to search in an arraylist from a user input but my if condition doesn't seem to work. Using boolean and .contains() doesn't work for my programme either. This is the coding:
String phone;
phone=this.text1.getText();
System.out.println("this is the phone: " + phone);
BufferedReader line = new BufferedReader(new FileReader(new File("C:\\Users\\Laura Sutardja\\Documents\\IB DP\\Computer Science HL\\cs\\data.txt")));
String indata;
ArrayList<String[]> dataArr = new ArrayList<String[]>();
while ((indata = line.readLine()) != null) {
String[] club = new String[2];
String[] value = indata.split(",", 2);
//for (int i = 0; i < 2; i++) {
int n = Math.min(value.length, club.length);
for (int i = 0; i < n; i++) {
club[i] = value[i];
}
boolean aa = dataArr.contains(this.text1.getText());
if(aa==true)
text2.setText("The data is found.");
else
text2.setText("The data is not found.");
dataArr.add(club);
}
for (int i = 0; i < dataArr.size(); i++) {
for (int x = 0; x < dataArr.get(i).length; x++) {
System.out.printf("dataArr[%d][%d]: ", i, x);
System.out.println(dataArr.get(i)[x]);
}
}
}
catch ( IOException iox )
{
System.out.println("Error");
}

Your dataArr is a list of String[], and you are searching for a String. The two are different kind of objects.
I don't really know how the content of the club array looks like, but you should either change dataArr in order to hold plain String, or to write a method which looks iteratively in dataArr for a String[] containing the output of this.text1.getText().

There is a lot wrong with the program. I assume you want to read a textfile and store each line in the arraylist. To do this you have to split each line of the textfile and store that array in the arrayList.
String[] value;
while ((indata = line.readLine()) != null) {
value = indata.split(",");
dataArr.add(value);
}
Now you have the contents of the file in the arrayList.
Next you want to compare the userinput with each element of the arraylist.
int j = 0;
for (int i = 0; i < dataArr.size(); i++) {
String[] phoneData = dataArr.get(i);
if (phoneData[1].equals(phone)) { // i am assuming here that the phone number is the 2nd element of the String[] array, since i dont know how the textfile looks.
System.out.println("Found number.");
club[j++] = phoneData[1];
} else if (i == dataArr.size()-1) {
System.out.println("Didn't find number.");
}
}
Edit:
As requested:
String phone;
phone = "38495";
System.out.println("this is the phone: " + phone);
BufferedReader line = new BufferedReader(new FileReader(new File("list.txt")));
String indata;
ArrayList<String[]> dataArr = new ArrayList<>();
String[] club = new String[2];
String[] value;// = indata.split(",", 2);
while ((indata = line.readLine()) != null) {
value = indata.split(",");
dataArr.add(value);
}
int j = 0;
for (int i = 0; i < dataArr.size(); i++) {
String[] phoneData = dataArr.get(i);
if (phoneData[1].equals(phone)) {
System.out.println("Found number.");
club[j++] = phoneData[1];
break;
} else if (i == dataArr.size()-1) {
System.out.println("Didn't find number.");
}
}
I hope this makes sense now.

Array throws NullPointerException in Java

I have the following little problem... I have this code that uses the method OpenFile() of one class ReadData to read a .txt file and also I have another class ArraysTZones used to create an object that stores 3 arrays (data1,data2,data3) and 3 integers (total1,total2,total3) returned by the method OpenFile(). The problem is that when I try to display each array (data1,data2,data3) using the method getArray() of ArrayTZones it stops and displays the error NullPointerException. Anyone knows how could I fix this?
public static void main (String args[]) throws IOException {
String fileName = ".//data.txt";
int[] def = new int[180];
try {
ReadData file = new ReadData(fileName);
ArraysTZones summaryatz = new ArraysTZones();
summaryatz = file.OpenFile();
for (int i = 0; i < 180; i++)
System.out.print (summaryatz.getArray1()[i] + " ");
System.out.println ("");
System.out.println (summaryatz.getTotal1());
for (int i = 0; i < 180; i++)
System.out.print (summaryatz.getArray2()[i] + " ");
System.out.println ("");
System.out.println (summaryatz.getTotal2());
for (int i = 0; i < 180; i++)
System.out.print (summaryatz.getArray3()[i] + " ");
System.out.println ("");
System.out.println (summaryatz.getTotal3());
}
catch (IOException e) {
System.out.println(e.getMessage());
}
}
Heres OpenFile()
public ArraysTZones OpenFile() throws IOException {
FileReader reader = new FileReader(path);
BufferedReader textReader = new BufferedReader(reader);
int numberOfTimeZones = 3;
int[] data1 = new int[180];
int[] data2 = new int[180];
int[] data3 = new int[180];
int total1 = 0;
int total2 = 0;
int total3 = 0;
ArraysTZones atz = new ArraysTZones();
for (int i = 0; i < numberOfTimeZones; i++){
if (i == 0) {
String firstTimeZone = textReader.readLine();
String[] val = firstTimeZone.split ("\\s+");
for (int u = 0; u < val.length; u++)
{
int stats = (int)(Math.ceil(Math.abs(Double.parseDouble(val[u]))));
total1 += stats;
data1[u] = stats;
}
total1= total1/180;
atz.setTotal1(total1);
atz.setArray1(data1);
}
else
if (i == 1) {
String secondTimeZone = textReader.readLine();
String[] val = secondTimeZone.split ("\\s+");
for (int u = 0; u < val.length; u++)
{
int stats = (int)(Math.ceil(Math.abs(Double.parseDouble(val[u]))));
total2 += stats;
data2[u] = stats;
}
total2= total2/180;
atz.setTotal2(total2);
atz.setArray2(data2);
}
else {
String thirdTimeZone = textReader.readLine();
String[] val = thirdTimeZone.split ("\\s+");
for (int u = 0; u < val.length; u++)
{
int stats = (int)(Math.ceil(Math.abs(Double.parseDouble(val[u]))));
total3 += stats;
data3[u] = stats;
}
total3= total3/180;
atz.setTotal3(total3);
atz.setArray3(data3);
}
}
textReader.close();
return atz;
}
The getArray()
public int[] getArray1 () {
return data1;
}
And setArray()
public void setArray1 (int[] farray) {
int[] data1 = new int[180];
//int[] farray = new int[180];
data1 = farray;
}

The problem seems to be here
public void setArray1 (int[] farray)
{
int[] data1 = new int[180];
//int[] farray = new int[180];
data1 = farray;
}
You're declaring a new variable called data1 and storing the content of farray to it.
After that method is done, that variable will be removed, due to his scope.
Remove int[] from the line int[] data1 = new int[180]; (or just remove the whole line .. it is unnecessary) and your data will be stored in the correct variable that was declared for the class.
public void setArray1 (int[] farray) {
data1 = farray;
}

You have to initialize ArraysTZones