So I am creating a program which when called, will have input, go to a file and change the number assigned to the string called. For example:
The file would look like:
stone 0 wood 5 water 2 metal 5
and if "wood" was called, it would go into the file, find wood then send add one to the value to the right of wood, which would only change that value to 6, then saves the file.
I've looked around on the internet but couldn't really find much which is tailored to my specific problem. Its either changing an int to either one or the other, or changing all ints to something.
public class Main {
public static void main(String[] args) {
FileWriter fw;
BufferedReader reader;
StringBuffer ib;
String allBlockAndNull = "stone 0 wood 5 water 2 metal 5";
String strDir = "C:\\Users\\amdro\\Desktop\\test.txt";
File fileDir = new File(strDir);
//creates file it doesn't exist
try {
fw = new FileWriter(fileDir);
fw.write(allBlockAndNull);
fw.close();
} catch (IOException e) {
e.printStackTrace();
}finally {}
}
}
If you could expand from the above, that would be great!
This is a very simple and basic solution to your problem: It consists of reading the file, appending all changes to a string and overwriting the same file with the string.
Create a scanner to read your text file and initialise a new string variable
Scanner s = new Scanner(new File("fileName.txt"));
String line = "";
While there is still a character in the text file, get the word and the number
while(sc.hasNext()){
String word = s.next();
int number = s.nextInt();
Then, inside the while loop, use switch and case to check the word. For example, if word = "wood", append "wood" and the new number, newNumber to line
case "wood":
line += word + " " + newNumber + " ";
break;
The default will be appending the word and the old number, number
default:
line += word + " " + number + " ";
Finally, just create a FileWriter and a BufferedWriter to write line to the text file.
You can't add numbers to a value from a file because all the values are Strings but what you can do is replace the String value
public static void main(String[] args) throws IOException {
File file = new File("file.txt");//The file containing stone 0 wood 5 water 2 metal 5
BufferedReader reader = new BufferedReader(new FileReader(file));
String words = "", list = "";
while ((words = reader.readLine()) != null) {
list += words;
}
reader.close();
Scanner s = new Scanner(file);
if(list.contains("wood")) {
String replacedtext = list.replaceAll("wood 5", "wood 6");
FileWriter writer = new FileWriter("file.txt");
writer.write(replacedtext);
writer.close();
}
}
}
Related
I read about someone having troubles with BufferedReader: the reader simply do not read the first lines. I have instead the opposite problem. For example, in a text file with 300 lines, it arrives at 200, read it half of it and then the following string is given null, so it stops.
private void readerMethod(File fileList) throws IOException {
BigInteger steps = BigInteger.ZERO;
BufferedReader br = new BufferedReader(new FileReader(fileList));
String st;
//reading file line by line
try{
while (true){
st = br.readLine();
if(st == null){
System.out.println("Null string at line " + steps);
break;
}
System.out.println(steps + " - " + st);
steps = steps.add(BigInteger.ONE);
}
}catch(Exception e){
e.printStackTrace();
}
finally{
try{
br.close();
}catch(Exception e){}
}
}
The output of the previous slice of code is as expected until it reaches line 199 (starting from 0). Consider a file with 300 lines.
...
198 - 3B02D5D572B66A82F9D21EE809320DB3E250C6C9
199 - 6E2C69795CB712C27C4097119CE2C5765
Null string at line 200
Notice that, all lines have the same length, so in this output line 199 is not even complete. I checked the file text, and it's correct: it contains all 300 lines and they are all of the same length. Also, in the text there are only capitals letters and numbers, as you can see.
My question is: how can i fix this? I need that the BufferedReader read all the text, not just a part of it.
As someone asked i add here the remaining part of the code. Please notice that all capital names are constant of various type (int, string etc).
This is the method that is called by the main thread:
public void init(){
BufferedWriter bw = null;
List<String> allLines = createRandomStringLines(LINES);
try{
String fileName = "SHA1_encode_text.txt";
File logFile = new File(fileName);
System.out.println(logFile.getCanonicalPath());
bw = new BufferedWriter(new FileWriter(logFile));
for(int i = 0; i < allLines.size(); i++){
//write file
String o = sha1FromString(allLines.get(i));
//sha1FromString is a method that change the aspect of the string,
//replacing char by char. Is not important at the moment.
bw.write(o + "\n");
}
}catch(Exception e){
e.printStackTrace();
}finally{
try{
bw.close();
}catch(Exception e){}
}
}
The method that create the list of random string is the following. "SYMBOLS" is just a String contains all avaiable chars.
private List<String> createRandomStringLines(int i) {
List<String> list = new ArrayList<String>();
while(i!=0){
StringBuilder builder = new StringBuilder();
int count = 64;
while (count-- != 0) {
int character = (int)(Math.random()*SYMBOLS.length());
builder.append(SYMBOLS.charAt(character));
}
String generatedString = builder.toString();
list.add(generatedString);
i--;
}
return list;
}
Note that, the file written is totally correct.
Okay, thanks to the user ygor, i manage to resolve it. The problem was that the BufferReader stars his job when the BufferWriter isn't closed yet. It was sufficient to move the command line that require the reader to work, after the bufferWriter.close() command.
I need some help in how to do a certain step as I can not seem to figure it out.
I was given a text file with 100 numbers in it all random, I am supposed to sort them either in ascending order, descending order, or both depending on the user input. Then which ever the user inputs the set of integers will be sorted and printed in a text file. I am having trouble printing the both file. Here is my code up until the both statement.
public static void print(ArrayList<Integer> output, String destination){
try {
PrintWriter print = new PrintWriter(destination);
for(int i = 0; i < output.size(); i++){
print.print(output.get(i) + " ");
}
print.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
BufferedReader br = null;
ArrayList<Integer> words = new ArrayList<>();
BufferedReader reader;
String numbers;
try {
reader = new BufferedReader(new FileReader("input.txt"));
while((numbers = reader.readLine()) != null)
{
words.add(Integer.parseInt(numbers));
}
System.out.println("How would you like to sort?");
System.out.println("Please enter asc(For Ascending), desc(For Decending), or both");
String answer = input.next();
Collections.sort(words);
if(answer.equals("asc")){
Collections.sort(words);
System.out.println(words);
print(words,"asc.txt");
}
else if(answer.equals("desc")){
Collections.reverse(words);
System.out.println(words);
print(words,"desc.txt");
When I type in "both" the text file that is created only has one column set of integers that is going in descending order, not both and I have no idea how to print both sets. If someone could shed some light I would really appreciate it.
else if(answer.equals("both")){
System.out.println(words);
print(words,"both.txt");
Collections.reverse(words);
System.out.println(words);
print(words,"both.txt");
You need to use FileOutputStreams#Constructor where you can pass a boolean value to tell whether to append to my file or not.
So use like this:
PrintWriter print = new PrintWriter(new FileOutputStream(destination, true));
/\
||
||
To append to the file
From JavaDocs
public FileOutputStream(File file,
boolean append)
throws FileNotFoundException
Parameters:
file - the file to be opened for writing.
append - if true, then bytes will be written to the end of the file
rather than the beginning
I am new in java. I just wants to read each string in java and print it on console.
Code:
public static void main(String[] args) throws Exception {
File file = new File("/Users/OntologyFile.txt");
try {
FileInputStream fstream = new FileInputStream(file);
BufferedReader infile = new BufferedReader(new InputStreamReader(
fstream));
String data = new String();
while ((data = infile.readLine()) != null) { // use if for reading just 1 line
System.out.println(""+data);
}
} catch (IOException e) {
// Error
}
}
If file contains:
Add label abc to xyz
Add instance cdd to pqr
I want to read each word from file and print it to a new line, e.g.
Add
label
abc
...
And afterwards, I want to extract the index of a specific string, for instance get the index of abc.
Can anyone please help me?
It sounds like you want to be able to do two things:
Print all words inside the file
Search the index of a specific word
In that case, I would suggest scanning all lines, splitting by any whitespace character (space, tab, etc.) and storing in a collection so you can later on search for it. Not the question is - can you have repeats and in that case which index would you like to print? The first? The last? All of them?
Assuming words are unique, you can simply do:
public static void main(String[] args) throws Exception {
File file = new File("/Users/OntologyFile.txt");
ArrayList<String> words = new ArrayList<String>();
try {
FileInputStream fstream = new FileInputStream(file);
BufferedReader infile = new BufferedReader(new InputStreamReader(
fstream));
String data = null;
while ((data = infile.readLine()) != null) {
for (String word : data.split("\\s+") {
words.add(word);
System.out.println(word);
}
}
} catch (IOException e) {
// Error
}
// search for the index of abc:
for (int i = 0; i < words.size(); i++) {
if (words.get(i).equals("abc")) {
System.out.println("abc index is " + i);
break;
}
}
}
If you don't break, it'll print every index of abc (if words are not unique). You could of course optimize it more if the set of words is very large, but for a small amount of data, this should suffice.
Of course, if you know in advance which words' indices you'd like to print, you could forego the extra data structure (the ArrayList) and simply print that as you scan the file, unless you want the printings (of words and specific indices) to be separate in output.
Split the String received for any whitespace with the regex \\s+ and print out the resultant data with a for loop.
public static void main(String[] args) { // Don't make main throw an exception
File file = new File("/Users/OntologyFile.txt");
try {
FileInputStream fstream = new FileInputStream(file);
BufferedReader infile = new BufferedReader(new InputStreamReader(fstream));
String data;
while ((data = infile.readLine()) != null) {
String[] words = data.split("\\s+"); // Split on whitespace
for (String word : words) { // Iterate through info
System.out.println(word); // Print it
}
}
} catch (IOException e) {
// Probably best to actually have this on there
System.err.println("Error found.");
e.printStackTrace();
}
}
Just add a for-each loop before printing the output :-
while ((data = infile.readLine()) != null) { // use if for reading just 1 line
for(String temp : data.split(" "))
System.out.println(temp); // no need to concatenate the empty string.
}
This will automatically print the individual strings, obtained from each String line read from the file, in a new line.
And afterwards, I want to extract the index of a specific string, for
instance get the index of abc.
I don't know what index are you actually talking about. But, if you want to take the index from the individual lines being read, then add a temporary variable with count initialised to 0.
Increment it till d equals abc here. Like,
int count = 0;
for(String temp : data.split(" ")){
count++;
if("abc".equals(temp))
System.out.println("Index of abc is : "+count);
System.out.println(temp);
}
Use Split() Function available in Class String.. You may manipulate according to your need.
or
use length keyword to iterate throughout the complete line
and if any non- alphabet character get the substring()and write it to the new line.
List<String> words = new ArrayList<String>();
while ((data = infile.readLine()) != null) {
for(String d : data.split(" ")) {
System.out.println(""+d);
}
words.addAll(Arrays.asList(data));
}
//words List will hold all the words. Do words.indexOf("abc") to get index
if(words.indexOf("abc") < 0) {
System.out.println("word not present");
} else {
System.out.println("word present at index " + words.indexOf("abc"))
}
The scanner reads the wrong data, the text file format is:
111，Smith，Sam, 40，10.50
330，Jones，Jennifer，30，10.00
The program is:
public class P3 {
public static void main(String[] args) {
String file=args[0];
File fileName = new File(file);
try {
Scanner sc = new Scanner(fileName).useDelimiter(", ");
while (sc.hasNextLine()) {
if (sc.hasNextInt( ) ){ int id = sc.nextInt();}
String lastName = sc.next();
String firstName = sc.next();
if (sc.hasNextInt( ) ){ int hours = sc.nextInt(); }
if (sc.hasNextFloat()){ float payRate=sc.nextFloat(); }
System.out.println(firstName);
}
sc.close();
} catch(FileNotFoundException e) {
System.out.println("Can't open file "
+ fileName + " ");
}
}
}
The output is:
40，10.50
330，Jones，Jennifer，30，10.00
It is supposed to be:
Sam
Jennifer
How do I fix it?
The problem is that your data isn't just delimited by commas. It is also delimited by line-endings, and also by Unicode character U+FF0C (FULLWIDTH COMMA).
I took your code, replaced the line
Scanner sc = new Scanner(fileName).useDelimiter(", ");
with
Scanner sc = new Scanner(fileName, "UTF-8").useDelimiter(", |\r\n|\n|\uff0c");
and then ran it. It produced the output it was supposed to.
The text , |\r\n|\n|\uff0c is a regular expression that matches either:
a comma followed by a space,
a carriage-return (\r) followed by a newline (\n),
a newline on its own,
a Unicode full-width comma (\uff0c).
These are the characters we want to delimit the text by. I've specified both types of line-ending as I'm not sure which line-endings your file uses.
I've also set the scanner to use the UTF-8 encoding when reading from the file. I don't know whether that will make a difference for you, but on my system UTF-8 isn't the default encoding so I needed to specify it.
First, please swap fileName and file. Next, I suggest you use a try-with-resources. Your variables need to be at a common scope if you intend to use them. Finally, when using hasNextLine() I would then call nextLine and you can split on optional white space and comma. That could look something like
String fileName = // ...
File file = new File(fileName);
try (Scanner sc = new Scanner(file)) {
while (sc.hasNextLine()) {
String line = sc.nextLine();
String[] arr = line.split("\\s*,\\s*");
int id = Integer.parseInt(arr[0]);
String lastName = arr[1];
String firstName = arr[2];
int hours = Integer.parseInt(arr[3]);
float payRate = Float.parseFloat(arr[4]);
System.out.println(firstName);
}
} catch (FileNotFoundException e) {
System.out.println("Can't open file " + fileName + " ");
e.printStackTrace();
}
How to get regex to get the value after name = in a file, and replace it.
I have a file called: 'myfile.txt'.
public static void main(String[] args)
File TextFile = new File("C:\\text.txt");
if (TextFile.exists()) {
try {
ReplaceWordInFile(TextFile, "haical", "arnanda");
} catch (IOException e) {
e.printStackTrace();
}
}
}
private static void ReplaceWordInFile(File MyFile, String OldText, String NewText)
throws IOException {
File tempFile = File.createTempFile("filetemp", ".tmp");
FileWriter fw = new FileWriter(tempFile);
Reader fr = new FileReader(MyFile);
BufferedReader br = new BufferedReader(fr);
while (br.ready()) {
fw.write(br.readLine().replaceAll(OldText, NewText) + "\n");
}
fw.close();
br.close();
fr.close();
tempFile.renameTo(MyFile);
}
Contents of the file C:\text.txt is:
name = haical
address = Michigan 48309, Amerika Serikat
age = 19
gender = male
activity = school
hoby = hiking, travel
If I run the program above in the first line, name = haical will change to name = arnanda.
My problem is that the value from name isn't 'haical' but another value, so I want to get the value after name = blablabla.
Furthermore, sometimes the statement name = haical won't keep it's number of spaces & changes its position.
Example of the contents of the output at a later time is:
address = Michigan 48309, Amerika Serikat
name = haical
age = 19
gender = male
activity = school
hoby = hiking, travel
So it's not always on the first line and some spaces after the = , but it will always be on line starting with name =.
Thanks in advance.
use
....replaceAll("^name\\s*=\\s*" + YourNameVariableToReplace + "\\s*$", "name="+YourNameVariableToInsert)
to replace the string. Maybe you need to escape the Name First, if he might contain Regex-Control-Chars.