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Writing string to file after particular string [duplicate]

This question already has answers here:
How to append text to an existing file in Java?
(31 answers)
Closed 7 years ago.
I want to write particular string in a file after a string. My file has this already -
##############################
path :
I need to write the String /sdcard/Docs/MyData after path :
Could anyone tell me how I could achieve this?

If I understand correctly you mean to append your path at the end of your file.
If so the use of a FileWriter is a good way to do it.
new FileWriter("Your path", true)
Notice that the boolean true in this case indicates that you want to append to your file, removing this altogether or using false instead would mean you want to overwrite the file.
An example for your case:
try(PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter("C:/YourEpicPath/ThisFileNeedsSomeAppending.txt", true)))) {
out.println("/sdcard/Docs/MyData");
}catch (IOException e1) {
//exception handling left as an exercise for the reader
}
Here is some documentation if you need for android, normally there shouldn't be any big differences.

How to ensure overwriting doesn't happen while writing to text file from console in java? [duplicate]

This question already has answers here:
File Write - PrintStream append
(2 answers)
Closed 7 years ago.
I am trying to write the console output to the text file (Data.txt) so here is my code:
PrintStream out = new PrintStream(new File("/home/cse/Desktop/Data.txt"));
System.setOut(out);
out.print("");
When I run the program again after I have once run it, the output replaces the old data that was present in the Data.txt file. But I want it to continue adding the data from where it had stopped earlier. How can I do this?

You need to pass a FileOutputStream created with the constructor that accepts an append flag:
PrintStream out = new PrintStream(new FileOutputStream("/home/cse/Desktop/Data.txt", true));
The true states the new content will be appended to an existing file.

Using out.append() should do the job for you.
PrintStream out = new PrintStream(new File("/home/cse/Desktop/Data.txt"));
System.setOut(out);
out.append("");

How to write to a file without deleting privious existing data [duplicate]

This question already has answers here:
How to append text to an existing file in Java?
(31 answers)
Closed 7 years ago.
I am try to write data to a text file. I am using this code:
try (Writer writer = new BufferedWriter(new OutputStreamWriter(
new FileOutputStream("filename.txt"), "utf-8"))) {
writer.write("something");
}
But while the program is running, the file is overwriting the exist data that are already found in the text file. How can i write new data lines to the same text file without overwriting it ? Is there any easy and simple way to write it?

try (Writer writer = Files.newBufferedWriter(
Paths.get("filename.txt"), StandardCharsets.UTF_8,
StandardOpenOption.WRITE,
StandardOpenOption.APPEND)) {
writer.write("something");
}
The open options are a varargs list, and default to new file creation.
BTW FileWriter uses the platform encoding, so you where right to not use that class. It is not portable.

I think you may use FileWriter(File file, Boolean append)
Constructs a FileWriter object given a File object. If the second
argument is true, then bytes will be written to the end of the file
rather than the beginning.

Write a string in a file exactly how it is [duplicate]

This question already has answers here:
How to write new line character to a file in Java
(9 answers)
Closed 8 years ago.
How is possible to write a string in a file .txt exactly how it is?
For example, I want to write exactly the following string :
Hello, I'm an user of stackoverflow
and I'm asking a question
I tried with BufferedWriter, PrintWriter, PrintStream, but the result is always the same, so in my file .txt the string appears like this :
Hello, I'm an user of stackoverflow and I'm asking a question
It is necessary to analyze each character or is there an easier way?

The problem seems to be the line breaks.
If you use PrintWriter.println() the platform specific line separator is used: "\r\n" on Windows.
Windows Notepad will not handle "\n" but WordPad does.

Use any one
System.lineSeparator() to a new line after adding first message
PrintWriter#println() method to add a new line
Sample code: (Try any one)
try (BufferedWriter writer = new BufferedWriter(new FileWriter("abc.txt"))) {
writer.write("Hello, I'm an user of stackoverflow");
writer.newLine();
writer.write("and I'm asking a question");
}
try (PrintWriter writer = new PrintWriter(new FileWriter("abc.txt"))) {
writer.write("Hello, I'm an user of stackoverflow");
writer.println();
writer.write("and I'm asking a question");
}
try (FileWriter writer = new FileWriter("abc.txt")) {
writer.write("Hello, I'm an user of stackoverflow");
writer.write(System.lineSeparator());
writer.write("and I'm asking a question");
}
Read more about Java 7 The try-with-resources Statement to handle the resources carefully.

You can use the newLine() method of BufferedWriter class.
A newLine() method is provided, which uses the platform's own notion
of line separator as defined by the system property line.separator.
Not all platforms use the newline character ('\n') to terminate lines.
Calling this method to terminate each output line is therefore
preferred to writing a newline character directly.
You may try like this using \n as well:
String s ="Hello, I'm an user of stackoverflow\n"
+"and I'm asking a question";
or
String s = String.format("%s\n%s","Hello, I'm an user of stackoverflow",
"and I'm asking a question");

RandomAccessFile setLength(0) adding a string of null characters to a file [duplicate]

This question already has answers here:
Clear contents of a file in Java using RandomAccessFile
(2 answers)
Closed 9 years ago.
I am trying to clear the contents of a file I made in java. The file is created by a PrintWriter call. I read here that one can use RandomAccessFile to do so, and read somewhere else that this is in fact better to use than calling a new PrintWriter and immediately closing it to overwrite the file with a blank one.
However, using the RandomAccessFile to clear the file seems to be adding a string of null characters to the file (or perhaps it is the PrintWriter?) It only occurs if more text is added.
PrintWriter writer = new PrintWriter("temp","UTF-8");
while (condition) {
writer.println("Example text");
if (clearCondition) {
writer.flush();
new RandomAccessFile("temp","rw").setLength(0);
// Although the solution in the link above did not include ',"rw"'
// My compiler would not accept without a second parameter
writer.println("Text to be written onto the first line of temp file");
}
}
writer.close();
Running the equivalent of the above code is giving my temp file the contents:
^#^#^#^#^#^#^#^#^#^#^#^#^#Text to be written onto the first line of temp file
The number of null characters is equal to the number of characters erased (including newline characters). If no new text is added to the file, it is completely blank.
NOTE: writer needs to be able to write "Example Text" to the file again after the file is cleared. The clearCondition does not mean that the while loop gets broken.
EDIT: I have no idea what caused those null characters. I realized I am stupid and there was no need to have a temp file, just a temp String with all the data that would later be written to a file. Strings are super easy to reset with = ""; Thanks for all the suggestions

It doesn't seem a good idea to have an opened PrintWriter on the file and use a RandomAccessFile at the same time.
If you close your writer and open a new one on the file (instead of using RandomAccessFile) I think it will suit your needs.