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Reading from a file and storing the first Integer as a String and the rest as Integers

I am trying to read a file and store the individual integers, but make the first integer in the file into a String. I have been able to read the file but I am struggling to store the integers respectively. I want to use them within the program.
The file has three integers per line separated by a whitespace.
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class arrayListStuffs2 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("Please enter the file name: e.g \'test.txt\'");
String fileName = sc.nextLine();
try {
sc = new Scanner(new File(fileName));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
List<String> listS = new ArrayList<>();
List<Integer> listI = new ArrayList<>();
while (sc.hasNextLine()) {
listI.add(sc.nextInt());
}
System.out.println(listI);
}
}

You can use the following approach. Iterate lines, split it, take first as string and other two as integer (assuming that you have data as
1 2 3
4 5 6
7 8 9
):
List<String> listS = new ArrayList();
List<Integer> listI = new ArrayList();
// try with resource automatically close resources
try (BufferedReader reader = Files.newBufferedReader(Paths.get("res.txt")))
{
reader.lines().forEach(line -> {
String[] ints = line.split(" ");
listS.add(String.valueOf(ints[0]));
listI.add(Integer.parseInt(ints[1]));
listI.add(Integer.parseInt(ints[2]));
});
} catch (IOException e) {
e.printStackTrace();
}
Output is :

Scanning integer and string from file in Java

I'm new to Java and I have to read from a file, and then convert what I have read into variables. My file consists of a fruit, then a price and it has a long list of this. The file looks like this:
Bananas,4
Apples,5
Strawberry,8
...
Kiwi,3
So far I have created two variables(double price and String name), then set up a scanner that reads from the file.
public void read_file(){
try{
fruits = new Scanner(new File("fruits.txt"));
print_file();
}
catch(Exception e){
System.out.printf("Could not find file\n");
}
}
public void print_file(){
while(fruits.hasNextLine()){
String a = fruits.nextLine();
System.out.printf("%s\n", a);
return;
}
}
Currently I am only able to print out the entire line. But I was wondering how I could break this up to be able to store the lines into variables.

So your string a has an entire line like Apples,5. So try to split it by comma and store it into variables.
String arr[] = a.split(",");
String name = arr[0];
int number = Integer.parseInt(arr[1]);
Or if prices are not integers, then,
double number = Double.parseDouble(arr[1]);

Using java 8 stream and improved file reading capabilities you can do it as follows. it stores item and count as key value pair in a map. It is easy to access by key afterwards.
I know this Maybe too advance but eventually this will help you later when getting to know new stuff in java.
try (Stream<String> stream = Files.lines(Paths.get("src/test/resources/items.txt"))) {
Map<String, Integer> itemMap = stream.map(s -> s.split(","))
.collect(toMap(a -> a[0], a -> Integer.valueOf(a[1])));
System.out.println(itemMap);
} catch (IOException e) {
e.printStackTrace();
}
output
{Apples=5, Kiwi=3, Bananas=4, Strawberry=8}

You can specify a delimiter for the scanner by calling the useDelimiter method, like:
public static void main(String[] args) {
String str = "Bananas,4\n" + "Apples,5\n" + "Strawberry,8\n";
try (Scanner sc = new Scanner(str).useDelimiter(",|\n")) {
while (sc.hasNext()) {
String fruit = sc.next();
int price = sc.nextInt();
System.out.printf("%s,%d\n", fruit, price);
}
} catch (Exception e) {
e.printStackTrace(System.out);
}
}

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class Test {
public static void main(String[] args) {
BufferedReader reader;
try {
reader = new BufferedReader(new FileReader(
"C://Test/myfile.txt")); //Your file location
String line = reader.readLine(); //reading the line
while(line!=null){
if(line!=null && line.contains(",")){
String[] data = line.split(",");
System.out.println("Fruit:: "+data[0]+" Count:: "+Integer.parseInt(data[1]));
}
//going over to next line
line = reader.readLine();
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}

reading/writing variables from text files to variables

I need to make a system for storing customer information and all quotations to an external file as well as entering more customers, listing customers, and the same with the quotations. As well as this I need to link all quotations/customers to an ID. I basically need to do SQL in java. However, I really need help with my input and output system, and writing all info to an array. I have got two main pieces of code but they are very inefficient and I need some suggestions, improvements or an entirely different system.
Input from file Code:
import java.io.*; //import classes
import java.util.ArrayList;
import java.util.Iterator;
public class MyTextReader{
public static void main(String[] args){
String myDirectory = System.getProperty("user.dir");
String fullDirectory = myDirectory + "\\myText.txt";
String input_line = null;
ArrayList<String> textItems = new ArrayList<String>(); //create array list
try{
BufferedReader re = new BufferedReader(new FileReader(fullDirectory));
while((input_line = re.readLine()) != null){
textItems.add(input_line); //add item to array list
}
}catch(Exception ex){
System.out.println("Error: " + ex);
}
Iterator myIteration = textItems.iterator(); //use Iterator to cycle list
while(myIteration.hasNext()){ //while items exist
System.out.println(myIteration.next()); //print item to command-line
}
}
}
Output to File
import java.io.FileWriter; //import classes
import java.io.PrintWriter;
public class MyTextWriter{
public static void main(String[] args){
FileWriter writeObj; //declare variables (uninstantiated)
PrintWriter printObj;
String myText = "Hello Text file";
try{ //risky behaviour – catch any errors
writeObj = new FileWriter("C:\\Documents\\myText.txt" , true);
printObj = new PrintWriter(writeObj);//create both objects
printObj.println(myText); //print to file
printObj.close(); //close stream
}catch(Exception ex){
System.out.println("Error: " + ex);
}
}
}

For reading text from a file
FileReader fr = new FileReader("YourFile.txt");
BufferedReader br = new BufferedReader(fr);
String s="";
s=br.readLine();
System.out.println(s);
For Writting Text to file
PrintWriter writeText = new PrintWriter("YourFile.txt", "UTF-8");
writeText.println("The first line");
writeText.println("The second line");
writeText.close();

JAVA String Reversing order of string in file io

I have to write code that will reverse the order of the string and write it in a new file. For example :
Hi my name is Bob.
I am ten years old.
The reversed will be :
I am ten years old.
Hi my name is Bob.
This is what I have so far. Not sure what to write for the outWriter print statement. Any help will be appreciated. Thanks!
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
public class FileRewinder {
public static void main(String[] args) {
File inputFile = new File("ascii.txt");
ArrayList<String> list1 = new ArrayList<String>();
Scanner inputScanner;
try {
inputScanner = new Scanner(inputFile);
} catch (FileNotFoundException f) {
System.out.println("File not found :" + f);
return;
}
while (inputScanner.hasNextLine()) {
String curLine = inputScanner .nextLine();
System.out.println(curLine );
}
inputScanner.close();
File outputFile = new File("hi.txt");
PrintWriter outWriter = null;
try {
outWriter = new PrintWriter(outputFile);
} catch (FileNotFoundException e) {
System.out.println("File not found :" + e);
return;
}
outWriter.println(???);
outWriter.close();
}
}

My suggestion is read entire file first and store sentences(you can split by .) in a LinkedList<String>(this will keep insertion order)
Then use Iterator and get sentences in reverse order. and write them into a file. make sure to put . just after each sentence.

After System.out.println(curLine ); add list1.add(curline); that will place your lines of text into your list.
At the end create a loop over list1 backwards:
for(int i = list1.size() - 1 , i > 0, --i) {
outWriter.println(list1[i]);
}

If the file contains an amount of lines which can be loaded into the memory. You can read all lines into a list, reverse the order of the list and write the list back to the disk.
public class Reverse {
static final Charset FILE_ENCODING = StandardCharsets.UTF_8;
public static void main(String[] args) throws IOException {
List<String> inLines = Files.readAllLines(Paths.get("ascii.txt"), FILE_ENCODING);
Collections.reverse(inLines);
Files.write(Paths.get("hi.txt"), inLines, FILE_ENCODING);
}
}

Storing String from file in an ArrayList object?

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
public class Cities {
public static void main(String[] args) throws IOException {
String filename;
System.out.println("Enter the file name : ");
Scanner kb = new Scanner(System.in);
filename = kb.next();
//Check if file exists
File f = new File(filename);
if(f.exists()){
//Read file
File myFile = new File(filename);
Scanner inputFile = new Scanner(myFile);
//Create arraylist object
ArrayList<String> list = new ArrayList<String>();
String cit;
while(inputFile.hasNext()){
cit = inputFile.toString();
list.add(inputFile.toString());
}
System.out.println(list);
}else{
System.out.println("File not found!");
}
}
}
I am trying to read a file and add the contents to an arraylist object (.txt file contains strings), but I am totally lost. Any advice?

You should read the file one line by one line and store it to the list.
Here is the code you should replace your while (inputFile.hasNext()):
Scanner input = null;
try
{
ArrayList<String> list = new ArrayList<String>();
input = new Scanner( new File("") );
while ( input.hasNext() )
list.add( input.nextLine() );
}
finally
{
if ( input != null )
input.close();
}
And you should close the Scanner after reading the file.

If you're using Java 7+, then you can use the Files#readAllLines() to do this task for you, instead of you writing a for or a while loop yourself to read the file line-by-line.
File f = new File(filename); // The file from which input is to be read.
ArrayList<String> list = null; // the list into which the lines are to be read
try {
list = Files.readAllLines(f.toPath(), Charset.defaultCharset());
} catch (IOException e) {
// Error, do something
}

You can do it in one single line with Guava.
final List<String> lines = Files.readLines(new File("path"), Charsets.UTF8);
http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/io/Files.html#readLines(java.io.File, java.nio.charset.Charset)