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reading and writing files java

I have a float array which I stored in it some values from user input.
I have 2 methods one that saves the values stored in the array to a text file each value on a line and the second method rereads the values again and stores them in the array. for example, the user input was 1,2,3,4 I save them to a text file and then I read the same txt file now my array should display 8 elements 1,2,3,4,1,2,3,4.
the problem I'm having is that when I store these elements on the txt file it's storing them and adding like 100 zeros under them and when I'm calling the second method to reread these elements from the file it reads the zeros so when I'm displaying the elements in my array it's displaying 0,0,0,0 when it should display 1,2,3,4,1,2,3,4.
what might be causing me this problem?
public void saveValuesToFile(Scanner keyboard) {
try {
System.out.println("Enter name of file: ");
String fileName = keyboard.next();
File file = new File(fileName);
PrintWriter outputFile = new PrintWriter(file);
for(int i = 0; i < numbers.length; i++) {
outputFile.println(numbers[i]);
}
outputFile.close();
} catch (FileNotFoundException e) {
System.out.println("file dont exist");
e.printStackTrace();
}
}
public void readFromFile(Scanner keyboard) {
System.out.println("Enter file name");
String fileName = keyboard.next();
BufferedReader reader = null;
try {
reader = new BufferedReader (new FileReader(fileName));
String input = null;
while ((input = reader.readLine()) != null) {
for (int i = 0; i < numbers.length; i++) {
numbers[i] = Float.parseFloat(input);
}
}
}
catch (NumberFormatException | IOException e) {
e.printStackTrace();
}
}

You may check why the array is populated properly using additional println statement. In your version each element of array is populated with the same element read from the file. If you remove the inner loop, array will be populated properly.
int i=0;
while ((input = reader.readLine()) != null) {
numbers[i] = Float.parseFloat(input);
System.out.println((i) + "::"+numbers[i]);
i++;
}

Zeros are being added because you're saving numbers as float. If you store an integer 3 in a float variable it will be converted to a float equivalent which is 3.0
Also you don't need two loops here,
while ((input = reader.readLine()) != null) {
for (int i = 0; i < numbers.length; i++) {
numbers[i] = Float.parseFloat(input);
}
You can instead do following,
int i = 0;
while ((input = reader.readLine()) != null) {
numbers[i] = Float.parseFloat(input);
i++;
}
Following is a fully functional program of what you desire,
import java.util.Scanner;
import java.io.*;
public class Hello {
public static float[] numbers = {1,2,3,4,1,2,3,4};
public static void saveValuesToFile(Scanner keyboard) {
try {
System.out.println("Enter name of file: ");
String fileName = keyboard.next();
File file = new File(fileName);
PrintWriter outputFile = new PrintWriter(file);
for(int i = 0; i < numbers.length; i++) {
outputFile.println(numbers[i]);
}
outputFile.close();
} catch (FileNotFoundException e) {
System.out.println("file doesn't exist");
e.printStackTrace();
}
}
public static void readFromFile(Scanner keyboard) {
System.out.println("Enter file name");
String fileName = keyboard.next();
BufferedReader reader = null;
try {
reader = new BufferedReader (new FileReader(fileName));
String input = null;
int i = 0;
while ((input = reader.readLine()) != null) {
numbers[i] = Float.parseFloat(input);
i++;
}
for(int j = 0; j < numbers.length; j++) {
System.out.println(numbers[j]);
}
}
catch (NumberFormatException | IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
saveValuesToFile(scanner);
readFromFile(scanner);
}
}

Adding a substring to omit a part of the output

Below is my code...
The code below is taking a .txt file of some radiation read outs. My job is to find the max number of counts per minute in the file within 5 counts.
I'e got it working, but I need to omit the part of the line, so I thought I could make this piece of the code:
/* String temp = new String(data)
* temp=list.get(i);
* System.outprintln(temp.substring(0,16) +" ");
*/
and integrate it in. I keep trying several cases, and am not thinking. Any advice?
`import java.util.*;
//Import utility pack, *look at all classes in package.
import java.io.*;
//Good within directory.
public class counterRadiation {
private static String infile = "4_22_18.txt";
//Input
private static String outfile = "4_22_18_stripped.txt";
private static Scanner reader;
//Output
public static void main(String[] args) throws Exception{
//throw exception and then using a try block
try {
//Use scanner to obtain our string and input.
Scanner play = new Scanner(new File(infile));
/* String temp = new String(data)
* temp=list.get(i);
* System.outprintln(temp.substring(0,16) +" ");
*/
Writer writer = new BufferedWriter(new OutputStreamWriter(
new FileOutputStream(outfile), "utf-8"));
String lineSeparator = System.getProperty("line.separator");
play.useDelimiter(lineSeparator);
while (play.hasNext()) {
String line = play.next();
if (line.matches(dataList)) {
writer.write(line + "\r\n");
}
}
writer.close();
play.close();
try {
reader = new Scanner(new File(infile));
ArrayList<String> list = new ArrayList<String>();
while (reader.hasNextLine()) {
list.add(reader.nextLine());
}
int[] radiCount = new int[list.size()];
for (int i = 0; i < list.size();i++) {
String[] temp = list.get(i).split(",");
radiCount[i] = (Integer.parseInt(temp[2]));
}
int maxCount = 0;
for (int i = 0; i < radiCount.length; i++) {
if (radiCount[i] > maxCount) {
maxCount = radiCount[i];
}
}
for (int i = 0;i < list.size() ;i++) {
if(radiCount[i] >= maxCount - 4) {
System.out.println(list.get(i)+" "+ radiCount[i]);
}
}
}catch(FileNotFoundException e){
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}`

Although it is not quite clear what you want to get rid of you could use .indexOf(String str) to define the first occurrence of the sub-string you want to exclude. For example in your code:
String data = "useful bit get rid of this";
int index = data.indexOf("get rid of this");
System.out.println(data.substring(0,index) + "are cool");
//Expected result:
//"useful bits are cool"
from Java doc

JAVA trying to read a file it sets nextChar equal to a box thing instead of the next char in the save file. where have I gone wrong?

this is a debugger error and runs an infinite loop where shown.
I am trying to load a file and have the gameboard be set to the chars in the text file (which are saved previously by user as shown) but in the debugger problem it sets next nextChar infinitely to □ after the first char has been read. I have had multiple attempts at trying to fix this myself but I cannot find a solution. Any help on how to fix this bug would be greatly appreciated. If any more details are needed give voice and see questions answered hastily.
This is the saving section of code.
/**
* A method to save the current state of the game
*/
public static void saveGame()
{
FileOutputStream outputStream = null;
PrintWriter printWriter = null;
try
{
System.out.println("Please name the save game file.");
outputStream = new FileOutputStream(Genio.getString());
printWriter = new PrintWriter(outputStream);
int i, j =0;
for(i=0; i<row; i++)
{
for(j=0; j<col; j++)
{
printWriter.println(gameBoard[i][j]);
}
}
}
catch (IOException e)
{
System.out.println("Sorry an error occured during saving.");
}
finally
{
if (printWriter != null)
{
printWriter.close();
}
}
}
This is the loading section of code;
/**
* A method to load a game.
*/
public static void loadGame()
{
FileReader fileReader = null;
BufferedReader bufferedReader = null;
char nextChar;
String line;
try
{
System.out.println("Please enter the name of your save file:");
fileReader = new FileReader(Genio.getString());
bufferedReader = new BufferedReader(fileReader);
nextChar = (char)bufferedReader.read();
while ((line = bufferedReader.readLine()) != null)
{
for (int i=0; i<row; i++)
{
for (int j=0; j<col; j++)
{
if (nextChar == '-' || nextChar == 'Y' || nextChar == 'R') //Infinite loop here where nextChar = □
{
gameBoard[i][j] = nextChar;
nextChar = (char)bufferedReader.read();
System.out.print(gameBoard[i][j]);
line = bufferedReader.readLine();
}
else
{
nextChar = (char)bufferedReader.read();
j--;
}
}
System.out.print("\n");
}
line = bufferedReader.readLine();
}
System.out.println("1\t2\t3\t4\t5\t6\t7");
}
catch (IOException e)
{
System.out.println("Sorry an error occured during the loading of the file.");
}
finally
{
if (bufferedReader != null)
{
try
{
bufferedReader.close();
}
catch (IOException e)
{
System.out.println("Sorry, an error has occured when closing the file.");
}
}
}
}

Not sure why you are reading a line AND reading characters.
You need to read each line and process each character in that line, for example...
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
public class ReadConnect4 {
private static final String TEST_BOARD = "-------\n"
+ "-------\n"
+ "-------\n"
+ "-------\n"
+ "-Y-----\n"
+ "-Y--R--\n";
private static final int ROWS = 6;
private static final int COLS = 7;
public static void main(String[] args) throws Exception {
ByteArrayInputStream pretendFile = new ByteArrayInputStream(TEST_BOARD.getBytes());
char[][] board = readBoard(pretendFile);
printBoard(board);
}
private static void printBoard(char[][] board) {
for(int k = 0; k < board.length; k++) {
for(int j = 0; j < board[k].length; j++) {
System.out.print(board[k][j]);
}
System.out.println();
}
}
private static char[][] readBoard(InputStream stream) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
String line;
int row = 0;
char[][] result = new char[ROWS][COLS];
// Read each line, stop when end of file (line is null)...
while((line = reader.readLine()) != null) {
// For each column...
for(int col = 0; col < 7; col++) {
// Get character from line, store in array
result[row][col] = line.charAt(col);
}
row++;
}
return result;
}
}
OUTPUT:
-------
-------
-------
-------
-Y-----
-Y--R--
To answer your question "why does it read box things", it's probably reading the end-of-stream and returning the character equivalent of "-1"

Why does my file get null in Java?

Trying to read in a maze in from a textfile to Java.
import java.io.*;
public class Maze {
private char[][]mazeData;
public static void main(String[] args) {
Maze test = new Maze();
}
public Maze() {
BufferedReader reader = null;
try {
File f = new File("c://testing.txt");
String line = null;
int row = 0;
reader = new BufferedReader(new FileReader(f));
reader.mark((int)f.length());
while ((line = reader.readLine()) != null) {
line = reader.readLine();
row++;
}
reader.reset();
mazeData = new char[row][];
row = 0;
while ((line = reader.readLine()) != null) {
mazeData[row++] = line.toCharArray();
}
int col=mazeData[0].length;
for (int i=0; i < row; i++){
for (int j=0; j < col; j++){
System.out.print(mazeData[i][j]);
}
System.out.println();
}
reader.close();
} catch (IOException e) {
System.out.println("INVALID FILE");
}
}
}
I tested in another class and java could find the file there so i dont get why the exeption keeps happening.

If you would print the catched exception you would read java.io.IOException: Mark invalid. Which is thrown at reader.reset(); because the mark has been invalidated.
You can fix it by
reader.mark((int)f.length() + 1);
Anyway there is no need to process the file twice only to know the number of lines. You can read all lines into a List<String> and process the lines from that array.
List<String> lines = Files.readAllLines(Paths.get("c:/testing.txt"),
Charset.defaultCharset());
edit
A stripped down solution (based on your code) could be.
public class Maze {
private char[][] mazeData;
public static void main(String[] args) {
Maze test = new Maze();
}
public Maze() {
try {
List<String> lines = Files.readAllLines(Paths.get("c:/testing.txt"), Charset.defaultCharset());
mazeData = new char[lines.size()][];
for (int i = 0; i < lines.size(); i++) {
mazeData[i] = lines.get(i).toCharArray();
}
int columns = mazeData[0].length;
int rows = lines.size();
for (int i = 0; i < rows; i++) {
for (int j = 0; j < columns; j++) {
System.out.print(mazeData[i][j]);
}
System.out.println();
}
} catch (IOException ex) {
System.out.println("failed: " + ex.getMessage());
}
}
}
Keep few other comments:
- avoid to do I/O processing in a constructor
- split the code in logical blocks (one method per logical step), e.g. initMazed(), printMaze(), etc.

How do you store each value separately using comma then they store into separate array?

A simple data file which contains
1908,Souths,Easts,Souths,Cumberland,Y,14,12,4000
1909,Souths,Balmain,Souths,Wests,N
Each line represents a season of premiership and has the following format: year, premiers, runners up, minor premiers, wooden spooners, Grand Final held, winning score,
losing score, crowd
I know how to store a data into an array and use the delimiter, but I am not exactly sure how to store EACH data item by a comma into separate arrays? Some suggestions and what particular code to be used would be nice.
UPDATE:
I just added the code but it still didn't work. Here's the code:
import java.io.*;
import java.util.Scanner;
public class GrandFinal {
public static Scanner file;
public static String[] array = new String[1000];
public static void main(String[] args) throws FileNotFoundException {
File myfile = new File("NRLdata.txt");
file = new Scanner (myfile);
Scanner s = file.useDelimiter(",");
int i = 0;
while (s.hasNext()) {
i++;
array[i] = s.next();
}
for(int j=0; j<array.length; j++) {
if(array[j] == null)
;
else if(array[j].contains("Y"))
System.out.println(array[j] + " ");
}
}
}

Here you go. Use ArrayList. Its dynamic and convenient.
BufferedReader br = null;
ArrayList<String> al = new ArrayList();
String line = "";
try {
br = new BufferedReader(new FileReader("NRLdata.txt"));
while ((line = br.readLine()) != null) {
al.add(line);
}
} catch (Exception e) {
e.printStackTrace();
}
for (int i = 0; i < al.size(); i++) {
System.out.println(al.get(i));
}
What does not work in your case ?
Because your season array is empty. You need to define the length, for ex:
private static String[] season = new String[5];
This is not right because you don't know how many lines you are going to store. Which is why I suggested you to Use ArrayList.

After working around a bit, I have come up with following code:
private static File file;
private static BufferedReader counterReader = null;
private static BufferedReader fileReader = null;
public static void main(String[] args) {
try {
file = new File("C:\\Users\\rohitd\\Desktop\\NRLdata.txt");
counterReader = new BufferedReader(new FileReader(file));
int numberOfLine = 0;
String line = null;
try {
while ((line = counterReader.readLine()) != null) {
numberOfLine++;
}
String[][] storeAnswer = new String[9][numberOfLine];
int counter = 0;
fileReader = new BufferedReader(new FileReader(file));
while ((line = fileReader.readLine()) != null) {
String[] temp = line.split(",");
for (int j = 0; j < temp.length; j++) {
storeAnswer[j][counter] = temp[j];
System.out.println(storeAnswer[j][counter]);
}
counter++;
}
} catch (IOException e) {
e.printStackTrace();
}
}
catch (FileNotFoundException e) {
System.out.println("Unable to read file");
}
}
I have added counterReader and fileReader; which are used for counting number of lines and then reading the actual lines. The storeAnswer 2d array contains the information you need.
I hope the answer is better now.