If I have a file that contains for example:
results1: 2, 4, 5, 6, 7, 8, 9
results2: 5, 3, 7, 2, 8, 5, 2
I want to add the integers from each line to a array. One array
for each line. How can I do this with code that does only read the integers?
Here's what I got this far
String data = null;
try {
Scanner in = new Scanner(new File(myFile));
while (in.hasNextLine()) {
data = in.nextLine();
numbers.add(data);
}
in.close();
} catch (Exception e) {
}
Easy.
One line per array, not two as you have it. New line after each one.
Read each line as a String, discard the leading "resultsX:", and split what remains at a delimiter of your choosing (e.g. comma). Parse each into an integer and add it to a List.
I don't think that leading "results1: " is adding any value. Why do you have that?
public static void main(String[] args) throws IOException {
BufferedReader reader=null;
try {
reader = new BufferedReader(new FileReader(new File("PATH TO FILE")));
// Only works if File allways contains at least two lines ... all lines after the second
// will be ignored
System.out.println(String.format("Array 1 : %s", Arrays.toString(stringArray2IntArray(readNextLine(reader)))));
System.out.println(String.format("Array 2 : %s", Arrays.toString(stringArray2IntArray(readNextLine(reader)))));
} finally {
if (reader!=null) {
reader.close();
}
}
}
private static Integer[] stringArray2IntArray(String[] numStrings) {
List<Integer> result = new ArrayList<Integer>();
for (int i = 0; i < numStrings.length; i++) {
result.add(Integer.parseInt(numStrings[i].trim()));
}
return result.toArray(new Integer[numStrings.length]);
}
private static String[] readNextLine(BufferedReader reader) throws IOException {
return reader.readLine().split(":")[1].split(",");
}
Assuming you have an input file, like this:
2,4,5,6,7,8,9
5,3,7,2,8,5,2
here is a code snippet to load it:
String firstLine = "";
String secondLine = "";
File file = new File("path/to/file");
try {
BufferedReader br = new BufferedReader(new FileReader(file));
firstLine = br.readLine();
secondLine = br.readLine();
} catch(Exception e){
e.printStackTrace();
}
String[] firstResult = firstLine.split(",");
String[] secondResult = secondLine.split(",");
int[] firstIntegers = new int[firstResult.length];
for(int i = 0; i <= firstResult.length ; i++){
firstIntegers[i] = Integer.parseInt(firstResult[i]);
}
int[] secondIntegers = new int[secondResult.length];
for(int i = 0; i <= secondResult.length ; i++){
firstIntegers[i] = Integer.parseInt(secondResult[i]);
}
Open the file with a BufferedReader br and then read it line by line.
Store each line in an int array and add all those int arrays to a list. At the end, this list will contain all the int arrays that we wanted, so iterate this list to do whatever you want to do next.
String filePath = "/path/to/file";
BufferedReader br = null;
List<Integer[]> arrays = new ArrayList<>(); //this contains all the arrays that you want
try {
br = new BufferedReader(new FileReader(filePath));
String line = null;
while ((line = br.readLine()) != null) {
line = line.substring(line.indexOf(":")+2); //this starts the line from the first number
String[] stringArray = line.split(", ");
Integer[] array = new Integer[stringArray.length];
for (int i = 0; i < stringArray.length; ++i) {
array[i] = Integer.parseInt(stringArray[i]);
}
arrays.add(array);
}
} catch (FileNotFoundException ex) {
System.err.println(ex);
} catch (IOException ex) {
System.err.println(ex);
} finally {
try {
br.close();
} catch (Exception ex) {
System.err.println(ex);
}
}
Since ArrayLists keep insertion order, then, e.g., arrays.get(3) will give you the array of the fourth line (if there is such a line) and arrays.size() will give you the number of lines (i.e., int arrays) that are stored.
Related
i am trying to read float values from a .txt file to initialize an array but it is throwing a InputMismatchException
Here's the method and the sample values i am trying to read from the file are 4 2 1 4
public class Numbers {
private Float [] numbers;
public int default_size = 10;
String fileName = new String();
public void initValuesFromFile()
{
Scanner scan = new Scanner(System.in);
fileName = scan.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 need to read line from the file and split using space or even better \\s+ and then run a for loop for all items split into an array of strings and parse each number and store them in a List<Float> and this way will work even if you have multiple numbers in further different lines. Here is the code you need to try,
Float[] numbers = new Float[4];
Scanner scan = new Scanner(System.in);
String fileName = scan.next();
scan.close();
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader(fileName));
String input = null;
while ((input = reader.readLine()) != null) {
String nums[] = input.trim().split("\\s+");
for (int i = 0; i < numbers.length; i++) {
numbers[i] = Float.parseFloat(nums[i]);
}
break;
}
System.out.println(Arrays.toString(numbers));
} catch (NumberFormatException | IOException e) {
e.printStackTrace();
}
This prints,
[4.0, 2.0, 1.0, 4.0]
I have a text file with state-city values:-
These are the contents in my file:-
Madhya Pradesh-Bhopal
Goa-Bicholim
Andhra Pradesh-Guntur
I want to split the state and the city... Here is my code
FileInputStream fis= new FileInputStream("StateCityDetails.txt");
BufferedInputStream bis = new BufferedInputStream(fis);
int h=0;
String s;
String[] str=null;
byte[] b= new byte[1024];
while((h=bis.read(b))!=-1){
s= new String(b,0,h);
str= s.split("-");
}
for(int i=0; i<str.length;i++){
System.out.println(str[1]); ------> the value at 1 is Bhopal Goa
}
}
Also I have a space between Madhya Pradesh..
So i want to Remove spaces between the states in the file and also split the state and city and obtain this result:-
str[0]----> MadhyaPradesh
str[1]----> Bhopal
str[2]-----> Goa
str[3]----->Bicholim
Please Help..Thank you in advance :)
I would use a BufferedReader here, rather than the way you are doing it. The code snippet below reads each line, split on hyphen (-), and removes all whitespace from each part. Each component is entered into a list, in left to right (and top to bottom) order. The list is converted to an array at the end in case you need this.
List<String> names = new ArrayList<String>();
BufferedReader br = null;
try {
String currLine;
br = new BufferedReader(new FileReader("StateCityDetails.txt"));
while ((currLine = br.readLine()) != null) {
String[] parts = currLine.split("-");
for (int i=0; i < parts.length; ++i) {
names.add(parts[i].replaceAll(" ", ""));
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null) br.close();
} catch (IOException ex) {
ex.printStackTrace();
}
}
// convert the List to an array of String (if you require it)
String[] nameArr = new String[names.size()];
nameArr = names.toArray(nameArr);
// print out result
for (String val : nameArr) {
System.out.println(val);
}
I am trying to practice reading text from a file in java. I am little stuck on how I can read N amount of lines, say the first 10 lines in a file and then add the lines in an ArrayList.
Say for example, the file contains 1-100 numbers, like so;
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- ....
I want to read the first 5 numbers, so 1,2,3,4,5 and add it to an array list. So far, this is what I have managed to do but I am stuck and have no clue what to do now.
ArrayList<Double> array = new ArrayList<Double>();
InputStream list = new BufferedInputStream(new FileInputStream("numbers.txt"));
for (double i = 0; i <= 5; ++i) {
// I know I need to add something here so the for loop read through
// the file but I have no idea how I can do this
array.add(i); // This is saying read 1 line and add it to arraylist,
// then read read second and so on
}
You could try using a Scanner and a counter:
ArrayList<Double> array = new ArrayList<Double>();
Scanner input = new Scanner(new File("numbers.txt"));
int counter = 0;
while(input.hasNextLine() && counter < 10)
{
array.add(Double.parseDouble(input.nextLine()));
counter++;
}
This should loop through 10 lines adding each to the arraylist as long as there is more inputs in the file.
See this How to read a large text file line by line using Java?
I think this will work:
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
int i = 0;
while ((line = br.readLine()) != null)
{
if (i < 5)
{
// process the line.
i++;
}
}
br.close();
ArrayList<String> array = new ArrayList<String>();
//ArrayList of String (because you will read strings)
BufferedReader reader = null;
try {
reader = new BufferedReader(new FileReader("numbers.txt")); //to read the file
} catch (FileNotFoundException ex) { //file numbers.txt does not exists
System.err.println(ex.toString());
//here you should stop your program, or find another way to open some file
}
String line; //to store a read line
int N = 5; //max number of lines to read
int counter = 0; //current number of lines already read
try {
//read line by line with the readLine() method
while ((line = reader.readLine()) != null && counter < N) {
//check also the counter if it is smaller then desired amount of lines to read
array.add(line); //add the line to the ArrayList of strings
counter++; //update the counter of the read lines (increment by one)
}
//the while loop will exit if:
// there is no more line to read (i.e. line==null, i.e. N>#lines in the file)
// OR the desired amount of line was correctly read
reader.close(); //close the reader and related streams
} catch (IOException ex) { //if there is some input/output problem
System.err.println(ex.toString());
}
List<Integer> array = new ArrayList<>();
try (BufferedReader in = new BufferedReader(
new InputStreamReader(new FileInputStream("numbers.txt")))) {
for (int i = 0; i < 5; ++i) { // Loops 5 times
String line = in.readLine();
if (line == null) [ // End of file?
break;
}
// line does not contain line-ending.
int num = Integer.parseInt(line);
array.add(i);
}
} // Closes in.
System.out.println(array);
You can do this with:
try (BufferedReader reader = Files.newBufferedReader(Paths.get("numbers.txt"))) {
List<String> first10Numbers = reader.lines().limit(10).collect(Collectors.toList());
// do something with the list here
}
As complete example as JUnit test:
public class ReadFirstLinesOfFileTest {
#Test
public void shouldReadFirstTenNumbers() throws Exception {
Path p = Paths.get("numbers.txt");
Files.write(p, "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n11\n12\n".getBytes());
try (BufferedReader reader = Files.newBufferedReader(Paths.get("numbers.txt"))) {
List<String> first10Numbers = reader.lines().limit(10).collect(Collectors.toList());
List<String> expected = Arrays.asList("0", "1", "2", "3", "4", "5", "6", "7", "8", "9");
Assert.assertArrayEquals(expected.toArray(), first10Numbers.toArray());
}
}
}
ArrayList<Double> myList = new ArrayList<Double>();
int numberOfLinesToRead = 5;
File f = new File("number.txt");
Scanner fileScanner = new Scanner(f);
for(int i=0; i<numberOfLinesToRead; i++){
myList.add(fileScanner.nextDouble());
}
Make sure you have "numberOfLinesToRead" lines in your file.
BufferedReader br = new BufferedReader(new FileReader(file));
List<String> nlines = IntStream.range(0, hlines)
.mapToObj(i -> readLine(br)).collect(Collectors.toList());
String readLine(BufferedReader reader) {
try {
return reader.readLine();
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}
I have *.txt file with first row as name,address,mail id and second line with the values. I have to print this into two columns,the first one with the headings and second with the value using Java. how do I do this?
public class ReadFile1 {
public static void main(String[] args) {
BufferedReader br=null;
String sCurrentLine = null;
String delimiter = ",";
String[] filetags;
try {
br = new BufferedReader(new FileReader("path\\Read.txt"));
sCurrentLine = br.readLine();
StringBuffer result = new StringBuffer();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
String line = null;
try {
line = br.readLine();
} catch (IOException e) {
e.printStackTrace();
}
filetags = line.split(delimiter);
for(int i = 0;i < line.length(); i++)
{
System.out.println("****" +sCurrentLine);
String[] s = line.split(",");
for(int j = i-1; j<line.length();j++)
{
System.out.println("##############"+Arrays.toString(s));
}
}
}
}
This is what I tried. Ex: I have a file say,
line1) name,email,mobile and second
line2) john,j#abc.com,9876
line3) max,max#xyz.com,1234
Now, I need to print:
name john
email john#abc.com
moblie 9876
name max
email max#xyz.com
mobile 1234
Below is one way you may be able to get what you want, It is similar to how you have attempted but slightly more refined.
The File:
name,email,mobile and second
john,j#abc.com,9876
max,max#xyz.com,1234
The code:
//File is on my Desktop
Path myFile = Paths.get(System.getProperty("user.home")).resolve("Desktop").resolve("tester.txt");
//Try-With-Resources so we autoclose the reader after try block
try(BufferedReader reader = new BufferedReader(new FileReader(myFile.toFile()))){
String[] headings = reader.readLine().split(",");//Reads First line and gets headings
String line;
while((line = reader.readLine()) != null){//While there are more lines
String[] values = line.split(","); //Get the values
for(int i = 0; i < values.length; i++){//For each value
System.out.println(headings[i] + ": " + values[i]);//Print with a heading
}
}
} catch (IOException io) {
io.printStackTrace();
}
Good Luck!
Something like this should do the trick.
Read the file and store each line in a list.
Iterate through the list of lines
If it is safe to assume the first line will always be the title line, take the input and store it in a collection.
For the rest of the lines, split on the comma and use the index of the splitter array to refer to the title column.
List <String> lines = new ArrayList<String>();
Scanner scanner = new Scanner(new File("FileName.txt"));
while(scanner.hasNextLine()){
String line = scanner.nextLine();
lines.add(line);
}
scanner.close();
int lineNo = 0;
List <String> title = new ArrayList<String>();
for(String line : lines){
if(lineNo == 0){
String [] titles = line.split(",");
for(String t : titles){
title.add(t);
}
lineNo++;
}
else{
String input = line.split(",");
for(int i = 0; i<input.length; i++){
System.out.println(title.get(i) + ": " + input[i]);
}
lineNo++;
}
}
I've been having stressful issues all day on this program to read a text file for integers and storing the integers into an array. I thought I finally got the solution with the code below.
But unfortunately.. I have to loop through the file with the method hasNextLine().
Then using nextInt() to read integers from the file and store them into an array.
So using scanner constructor, hasNextLine(), next(), and nextInt() methods.
Then use try and catch to determine which words are integers and which are not by using the InputMismatchException. Also a exception for blank lines in the file?
Problem is I did not use a try and catch and exceptions, as I just skipped over none-ints.
Also, I'm using a int array so I want to do this without list.
public static void main(String[] commandlineArgument) {
Integer[] array = ReadFile4.readFileReturnIntegers(commandlineArgument[0]);
ReadFile4.printArrayAndIntegerCount(array, commandlineArgument[0]);
}
public static Integer[] readFileReturnIntegers(String filename) {
Integer[] array = new Integer[1000];
int i = 0;
//connect to the file
File file = new File(filename);
Scanner inputFile = null;
try {
inputFile = new Scanner(file);
}
//If file not found-error message
catch (FileNotFoundException Exception) {
System.out.println("File not found!");
}
//if connected, read file
if (inputFile != null) {
// loop through file for integers and store in array
try {
while (inputFile.hasNext()) {
if (inputFile.hasNextInt()) {
array[i] = inputFile.nextInt();
i++;
}
else {
inputFile.next();
}
}
}
finally {
inputFile.close();
}
System.out.println(i);
for (int v = 0; v < i; v++) {
System.out.println(array[v]);
}
}
return array;
}
public static void printArrayAndIntegerCount(Integer[] array, String filename) {
//print number of integers
//print all integers that are stored in array
}
}
Then I'll be printing everything in my 2nd method, but that I can worry about later. :o
Example Content of Text File:
Name, Number
natto, 3
eggs, 12
shiitake, 1
negi, 1
garlic, 5
umeboshi, 1
Sample Output Goal:
number of integers in file "groceries.csv" = 6
index = 0, element = 3
index = 1, element = 12
index = 2, element = 1
index = 3, element = 1
index = 4, element = 5
index = 5, element = 1
Sorry for the similar question. I'm very stressed out, and even more that I was doing it all wrong... I'm completely stuck at this point :(
You can read Your file in this way.
/* using Scanner */
public static Integer[] getIntsFromFileUsingScanner(String file) throws IOException {
List<Integer> l = new ArrayList<Integer>();
InputStream in = new FileInputStream(file);
Scanner s = new Scanner(in);
while(s.hasNext()) {
try {
Integer i = s.nextInt();
l.add(i);
} catch (InputMismatchException e) {
s.next();
}
}
in.close();
return l.toArray(new Integer[l.size()]);
}
/* using BufferedReader */
public static Integer[] getIntsFromFile(String file) throws IOException {
List<Integer> l = new ArrayList<Integer>();
BufferedReader reader = new BufferedReader(new FileReader(file));
String line;
while ((line = reader.readLine()) != null) {
try {
l.add(Integer.parseInt(line.split(",")[1]));
} catch (NumberFormatException e) {
}
}
return l.toArray(new Integer[l.size()]);
}
And with Your code:
public static void main(String[] commandlineArgument) {
Integer[] array = getIntsFromFileUsingScanner(commandlineArgument[0]);
ReadFile4.printArrayAndIntegerCount(array, commandlineArgument[0]);
}
Here is one way to meet your new requirements,
public static Integer[] readFileReturnIntegers(
String filename) {
Integer[] temp = new Integer[1000];
int i = 0;
// connect to the file
File file = new File(filename);
Scanner inputFile = null;
try {
inputFile = new Scanner(file);
}
// If file not found-error message
catch (FileNotFoundException Exception) {
System.out.println("File not found!");
}
// if connected, read file
if (inputFile != null) {
// loop through file for integers and store in array
try {
while (inputFile.hasNext()) {
try {
temp[i] = inputFile.nextInt();
i++;
} catch (InputMismatchException e) {
inputFile.next();
}
}
} finally {
inputFile.close();
}
Integer[] array = new Integer[i];
System.arraycopy(temp, 0, array, 0, i);
return array;
}
return new Integer[] {};
}
public static void printArrayAndIntegerCount(
Integer[] array, String filename) {
System.out.printf(
"number of integers in file \"%s\" = %d\n",
filename, array.length);
for (int i = 0; i < array.length; i++) {
System.out.printf(
"\tindex = %d, element = %d\n", i, array[i]);
}
}
Outputs
number of integers in file "/home/efrisch/groceries.csv" = 6
index = 0, element = 3
index = 1, element = 12
index = 2, element = 1
index = 3, element = 1
index = 4, element = 5
index = 5, element = 1
Maybe you can resolve this issue by brief code as I post below.
public static List<Integer> readInteger(String path) throws IOException {
List<Integer> result = new ArrayList<Integer>();
BufferedReader reader = new BufferedReader(new FileReader(path));
String line = null;
Pattern pattern = Pattern.compile("\\d+");
Matcher matcher = null;
line = reader.readLine();
String input = null;
while(line != null) {
input = line.split(",")[1].trim();
matcher = pattern.matcher(input);
if(matcher.matches()) {
result.add(Integer.valueOf(input));
}
line = reader.readLine();
}
reader.close();
return result;
}
Enclose try catch for below code:
try
{
if (inputFile.hasNextInt()) {
array[i] = inputFile.nextInt();
i++;
}
else {
inputFile.next();
}
}catch(Exception e)
{
// handle the exception
}