I am trying to duplicate the original into a new file. In the new file I want the exact same things as the original BUT no blank lines.
Note: I looked at other posts and tried with no success.
Currently:
1
2
3
How I want it to be: -- no blank lines
1
2
3
Here is my code so far:
inputFileName = "x.txt";
outputFileName = "y.txt";
inputFile = new BufferedReader(new FileReader(inputFileName));
outputFile = new PrintWriter(new FileWriter(outputFileName));
String lineOfText = inputFile.readLine();
while(lineOfText != null)
{
if (lineOfText.isEmpty())
{
outputFile.print("null");
}
outputFile.println(lineOfText);
lineOfText = inputFile.readLine();
}
inputFile.close();
outputFile.close();
}
Thank you for all who can possibly help. I assumed that print("null") would print out 'nothing' but it indeed prints out null, I do not know how to print out 'nothing'.
You need to skip the println in case the line is empty:
while(lineOfText != null)
{
if (!lineOfText.isEmpty()) {
outputFile.println(lineOfText);
}
lineOfText = inputFile.readLine();
}
You're on the right track, but this
while(lineOfText != null)
{
if (lineOfText.isEmpty())
{
outputFile.print("null");
}
outputFile.println(lineOfText);
lineOfText = inputFile.readLine();
}
shouldn't be writing null on empty lines. I think you wanted something like
while(lineOfText != null)
{
if (!lineOfText.isEmpty())
{
outputFile.println(lineOfText);
}
lineOfText = inputFile.readLine();
}
Also, I suggest you use a try-with-resources Statement instead of manually managing your close(s). It's probably a good idea to trim (as suggested in the comments) before your test, and you can simplify your loop and you should limit variable visibility. All together like,
String inputFileName = "x.txt";
String outputFileName = "y.txt";
try (BufferedReader inputFile = new BufferedReader(new FileReader(inputFileName));
PrintWriter outputFile = new PrintWriter(new FileWriter(outputFileName))) {
String lineOfText;
while ((lineOfText = inputFile.readLine()) != null) {
lineOfText = lineOfText.trim();
if (!lineOfText.isEmpty()) {
outputFile.println(lineOfText);
}
}
}
public static void main(String[] args) {
Scanner file;
PrintWriter writer;
try {
file = new Scanner(new File("src/data1.txt"));
writer = new PrintWriter("src/data2.txt");
while (file.hasNext()) {
String line = file.nextLine();
if (!line.isEmpty()) {
writer.write(line);
writer.write("\n");
}
}
file.close();
writer.close();
} catch (FileNotFoundException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
Related
The above is a working code snippet. The code runs fine but it does not write what is inside the else if(line.contains("{NEW_LIMIT}")) statement.
Another problem is that after the program writes into a new text file it loses its original format, as in to say it just writes everything in a single line.
Is there anything I am doing wrong?
public static void replace1(String name, String limit, String nlimit) throws IOException
{
File infile = new File("s://BlackBuck/Question_1_Template.txt");
File outfile = fileReturn();
FileWriter fw;
BufferedWriter bw = null;
FileReader fr;
BufferedReader br = null;
String line, putdata = null;;
try {
fr = new FileReader(infile);
br = new BufferedReader(fr);
fw = new FileWriter(outfile);
bw = new BufferedWriter(fw);
while((line = br.readLine()) != null)
{
if(line != null)
{
if(line.contains("{CUSTOMER_NAME}"))
{
putdata = line.replace("{CUSTOMER_NAME}", name);
bw.write(putdata);
}
else if(line.contains("{CURRENT_LIMIT}"))
{
putdata = line.replace("{CURRENT_LIMIT}", limit);
bw.write(putdata);
}
else if(line.contains("{NEW_LIMIT}"))
{
putdata = line.replace("{NEW_LIMIT}", nlimit);
bw.write(putdata);
}
else
{
bw.write(line);
}
}
}
}finally {
bw.close();
br.close();
}
}
If a line contains {CUSTOMER_NAME} or {CURRENT_LIMIT}, then statements {NEW_LIMIT} won't be run. You can simply fix this using following codes:
if(line != null) {
putdata = line.replace("{CUSTOMER_NAME}", name)
.replace("{CURRENT_LIMIT}", limit)
.replace("{NEW_LIMIT}", nlimit);
bw.write(putdata);
// append a line separator to current line
bw.newLine();
}
inputFileName = "2.txt";
outputFileName = "3.txt";
inputFile = new BufferedReader(new FileReader(inputFileName));
outputFile = new PrintWriter(new FileWriter(outputFileName));
String lineOfText = inputFile.readLine();
while (lineOfText != null)
{
if (lineOfText.contains("x"))
{
lineOfText = lineOfText.replaceAll("x"+ ".*", "");
}
outputFile.println(lineOfText);
lineOfText = inputFile.readLine();
}
inputFile.close();
outputFile.close();
Hello,
right now I have an input and output, does that mean I have two try and two catch blocks (there might be an error connecting to the previous file and writing to the second file). Or would I need only one try block?
If so, how/where would I implement the try and catch blocks?
I would only use one try/catch/finally-block by writing:
try {
inputFile = new BufferedReader(new FileReader(inputFileName));
outputFile = new PrintWriter(new FileWriter(outputFileName));
String lineOfText = inputFile.readLine();
while (lineOfText != null) {
if (lineOfText.contains("x")) {
lineOfText = lineOfText.replaceAll("x"+ ".*", "");
}
outputFile.println(lineOfText);
lineOfText = inputFile.readLine();
}
} catch(IOException ioe) {
System.err.println("Caught IOException: " + ioe.getMessage());
} finally {
if(inputFile != null)
inputFile.close();
if(outputFile != null)
outputFile.close();
}
By using the finally block you can be sure that the Reader and Writer object are definitely closed.
I would recommend using try with resources block of Java 7, as shown in the example below, it will take care of closing of resources as well:
public static void main(String[] args) throws Exception {
String inputFileName = "2.txt";
String outputFileName = "3.txt";
try (BufferedReader inputFile = new BufferedReader(new FileReader(inputFileName));
PrintWriter outputFile = new PrintWriter(new FileWriter(outputFileName));) {
String lineOfText = inputFile.readLine();
while (lineOfText != null) {
if (lineOfText.contains("x")) {
lineOfText = lineOfText.replaceAll("x" + ".*", "");
}
outputFile.println(lineOfText);
lineOfText = inputFile.readLine();
}
}catch(Exception e){
//Handle
}
}
Here is the documentation for try with resources.
I have a text file -> 23/34 <- and I'm working on a Java program.
I want to store them out in String One = 23 and anotherString = 34 and put them together to one string to write them down in a text file, but it dosen't work. :( Everytime it makes a break. Maybe because the split method but I don't know how to separate them.
try {
BufferedReader in = new BufferedReader (new FileReader (textfile) );
try {
while( (textfile= in.readLine()) != null ) {
String[] parts = textfileString.split("/");
String one = parts[0];
}
}
}
When I print or store one + "/" + anotherString, it makes a line-break at one but I want it all in one line. :(
public static void main(String[] args) throws Exception {
File file = new File("output.txt");
if (!file.exists()) {
file.createNewFile();
}
BufferedWriter bw = new BufferedWriter(new FileWriter(file.getAbsoluteFile()));
BufferedReader br = new BufferedReader(new FileReader("input.txt"));
String line = null;
while ((line = br.readLine()) != null) {
String string1 = line.split("/")[0];
String string2 = line.split("/")[1];
bw.write(string1 + string2 + "\n");
bw.flush();
}
br.close();
bw.close();
}
On file:
23/34
Resulted in output.txt containing:
2334
You need to read in each line, and split it on your designated character ("/"). Then assign string1 to the first split, and string2 to the second split. You can then do with the variables as you want. To output them to a file, you simply append them together with a + operator.
You have never shown us how you are writing the file, so we can't really help you with your code. This is a bit of a more modern approach, but I think it does what you want.
File infile = new File("input.txt");
File outfile = new File("output.txt");
try (BufferedReader reader = Files.newBufferedReader(infile.toPath());
BufferedWriter writer = Files.newBufferedWriter(outfile.toPath())) {
String line;
while ((line = reader.readLine()) != null) {
String parts[] = line.split("/");
String one = parts[0];
String two = parts[1];
writer.write(one + "/" + two);
}
} catch (IOException ex) {
System.err.println(ex.getLocalizedMessage());
}
InputStream stream = this.getClass().getResourceAsStream("./test.txt");
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
String currentLine;
try {
while ((currentLine = reader.readLine()) != null) {
String[] parts = currentLine.split("/");
System.out.println(parts[0] + "/" + parts[1]);
}
} catch (IOException e) {
e.printStackTrace();
} finally{
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
I have written the Java code to read from one file and write to a new file. The file from which I am reading has 5000 lines of records, but when I am writing to a new file I am able to write only between 4700-4900 records.
I think may be I am simultaneously reading from a file and writing to a file, which might be creating a problem.
My code is as follows:
Reading from a file:
public String readFile(){
String fileName = "/home/anand/Desktop/index.txt";
FileReader file = null;
try {
file = new FileReader(fileName);
BufferedReader reader = new BufferedReader(file);
String line = "";
while ((line = reader.readLine()) != null) {
line.replaceAll("ids", "");
System.out.println(line);
returnValue += line + "\n";
}
return returnValue;
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
if (file != null) {
try {
file.close();
} catch (IOException e) {
// Ignore issues during closing
}
}
}
}
Writing to a file:
public void writeFile(String returnValue){
String newreturnValue = returnValue.replaceAll("[^0-9,]", "");
String delimiter = ",";
String newtext ="";
String[] temp;
temp = newreturnValue.split(delimiter);
FileWriter output = null;
try {
output = new FileWriter("/home/anand/Desktop/newinput.txt");
BufferedWriter writer = new BufferedWriter(output);
for(int i =0; i < temp.length ; i++){
writer.write("["+i+"] "+temp[i]);
writer.newLine();
}
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
if (output != null) {
try {
output.close();
} catch (IOException e) {
// Ignore issues during closing
}
}
}
}
I need the suggestion to how to simultaneously read and write to a file.
You need to close writer instead of output. The BufferedWriter may not be writing all of the lines, and won't since you never close it.
You have to close the writer object. The last couple lines probably haven't been flushed onto the text file.
In addition, are you aware of the try-with-resource introduced in Java 7? You can condense your code to this by utilizing it:
public String readFile(){
String fileName = "/home/anand/Desktop/index.txt";
try(BufferedReader reader = new BufferedReader(new FileReader(filename)) {
String line = "";
while ((line = reader.readLine()) != null) {
line.replaceAll("ids", "");
System.out.println(line);
returnValue += line + "\n";
}
return returnValue;
} catch (Exception e) {
throw new RuntimeException(e);
}
}
By doing this, Java will automatically close the reader object for you once the try block completes, regardless of whether or not an exception was thrown. This makes it easier to read your code :)
Can anyone point me in the right direction here. I have a method that is supposed to read a file and display the data in that file. I can only get it to display one line. I know it is something simple I am over looking, but my brain is mush and I just keep digging a bigger hole.
public static String readFile(String file) {
String data = "";
if (!new java.io.File(file).exists()) {
return data;
}
File f = new File(file);
FileInputStream fStream = null;
BufferedInputStream bStream = null;
BufferedReader bReader = null;
StringBuffer buff = new StringBuffer();
try {
fStream = new FileInputStream(f);
bStream = new BufferedInputStream(fStream);
bReader = new BufferedReader(new InputStreamReader(bStream));
String line = "";
while (bStream.available() != 0) {
line = bReader.readLine();
if (line.length() > 0) {
if (line.contains("<br/>")) {
line = line.replaceAll("<br/>", " ");
String tempLine = "";
while ((tempLine.trim().length() < 1)
&& bStream.available() != 0) {
tempLine = bReader.readLine();
}
line = line + tempLine;
}
buff.append(line + "\n");
}
}
fStream.close();
bStream.close();
bReader.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return buff.toString();
}
String line = null;
while ((line = bReader.readLine())!=null)
How about doing this with Guava:
http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/io/Files.html
List<String> lines = Files.readLines("myFile.txt", Charset.forName("UTF-8"));
System.out.println(lines);
You'd still have to do a little bit of work to concatenate the <br> lines etc...