Develop Reference

How can I modify a particular line in a file without deleting the existing data using Java?

I need to change the values in a file which has more than 30 lines and each line has a data like:
ENABLE_TLS=true
PSWD_MIN_LENGTH=8
Here, let us consider this as a key and value pair, and I needed to change only the value for the 2nd line alone, without deleting the 1st line. Can someone help me how can I do this??
I have tried bufferedwriter, but it is replacing all the lines.
My expectation is:
I need to modify only a particular key's value and the remaining lines should not get deleted

Your description of the data sounds like Java Properties. If you are certain that all the data in that file takes the form key=value you could read it in as a Properties object, update the value for the key in question, and write it back to the file.
Properties properties = new Properties();
try (FileInputStream inputStream = new FileInputStream("/path/to/file")) {
properties.load(inputStream);
}
properties.put("PSWD_MIN_LENGTH", 12);
try (FileOutputStream outputStream = new FileOutputStream("/path/to/file")) {
properties.store(outputStream, null);
}
BEWARE: there is no guarantee that the order of the key/value entries in the file will be maintained (they probably won't). If you are looking for a Properties implementation that will maintain the order, maybe this SO answer will do the trick (UNTESTED!) How maintain the order of keys in Java properties file?

Java saving a file with special characters in file name

I'm having a problem on Java file encoding.
I have a Java program will save a input stream as a file with a given file name, the code snippet is like:
File out = new File(strFileName);
Files.copy(inStream, out.toPath());
It works fine on Windows unless the file name contains some special characters like Ö, with these characters in the file name, the saved file will display a garbled file name on Windows.
I understand that by applying JVM option -Dfile.encoding=UTF-8 this issue can be fixed, but I would have a solution in my code rather than ask all my users to change their JVM options.
While debugging the program I can see the file name string always shows the correct character, so I guess the problem is not about internal encoding.
Could someone please explain what went wrong behind the scene? and is there a way to avoid this problem programmatically? I tried get the bytes from the string and change the encoding but it doesn't work.
Thanks.

Using the URLEncoder class would work:
String name = URLEncoder.encode("fileName#", "UTF-8");
File output = new File(name);

java.util.MissingResourceException: Can't find resource for bundle java.util.PropertyResourceBundle, key

I don't know whats going on.
Here is my Titles_en_US.properties file:
WEBSITE.TITLE = Hello World
FOOTER.DISCLAIMER = Disclaimer
FOOTER.TERMS_OF_USE = Terms of Use
FOOTER.PRIVACY_POLICY = Privacy Policy
Here is my method:
private String getTitle() throws Exception {
System.out.println("\n\n==>"+getProperty("FOOTER.DISCLAIMER",LabelsFile()));
return getProperty("WEBSITE.TITLE", LabelsFile());
}
Both FOOTER.DISCLAIMER and WEBSITE.TITLE in same properties file but one is working and other is throwing following error:
==>Disclaimer
Resources.ResourceBundle.java:getProperty()
java.util.MissingResourceException: Can't find resource for bundle java.util.PropertyResourceBundle, key WEBSITE.TITLE
Please advise where I am making mistake?
UPDATE
I noticed that when I give line break then its working fine. Not able to understand why resource bundle is not reading from 1st line of property file?

I found that when I give a line break at top of my property file then it started work fine. Then I searched why the java ResourceBundle is not reading first line of the property file and found this POST. In this post said that:
The load(Reader) / store(Writer, String) methods load and store
properties from and to a character based stream in a simple
line-oriented format specified below. The load(InputStream) /
store(OutputStream, String) methods work the same way as the
load(Reader)/store(Writer, String) pair, except the input/output
stream is encoded in ISO 8859-1 character encoding.
and also in the aforementioned post advised to change the encoding of the properties file to ISO-8859-1.

Read Japanese Characters from a properties file using Resource Bundle

I am working on developing a project and when I attempt to read in a Japanese character string from a properties file using ResourceBundle in Java, all I get are a bunch of question marks (??????????) displayed in my application.
I know that I need to encode the string somehow, but I've tried several different ways with no luck. I've also tried to encode the properties file in a text editor but this doesn't seem to work how I'd like either. My code for retrieving the string is below. I know you can do this with stream readers and other methods but I would like to try to stay with the current code structure using ResourceBundle if possible. If anyone has any questions or needs clarification please feel free to let me know.
private final ResourceBundle bundle = ResourceBundle.getBundle("propertiesFile");
titleText = bundle.getString("title.text");
Just to give you an idea, title.text=会議参加者事前登録用ページ in my property file.
Any suggestions are appreciated. This has turned into a real pain.
Thanks again,
-Dave F.

ResourceBundle can only read ISO 8859-1 file. See this thread. How to use UTF-8 in resource properties with ResourceBundle
I had the same problem here, and I've converted my ResourceBundle to a Properties object like in the answer of this thread: read resourcebundle as UTF-8. getString() Method seems to change encoding to ISO-8859
Like this:
InputStream utf8in = getClass().getClassLoader().getResourceAsStream("/path/to/utf8.properties");
Reader reader = new InputStreamReader(utf8in, "UTF-8");
Properties props = new Properties();
props.load(reader);

After some research I was actually still able to make use of the ResourceBundle method.
In my properties file that ResourceBundle pulls from, I listed the following in unicode:
title.text=\u4f1a\u8b70\u53c2\u52a0\u8005\u4e8b\u524d\u767b\u9332\u7528\u30da\u30fc\u30b8
When pulled in by ResourceBundle, it translates as:
会議参加者事前登録用ページ
I'm sure this probably isn't the best practice, but it works without having to change how the entire project pulls in its resource properties, so I just thought I would share with you all for helping me out.

when you run your app you can try this:
java -Dfile.encoding=UTF-8 -jar YourApp.jar
this basically sets the default charset

Trailing null (\x00) characters when writing text to Accumulo

I am trying to write the name of a file into Accumulo. I am using accumulo-core-1.43.
For some reason, certain files seem to be written into Accumulo with trailing \x00 characters at the end of the name. The upload is coming through a Java servlet (using the jquery file upload plugin). In the servlet, I check the name of the file with a System.out.println and it looks normal, and I even tried unescaping the string with
org.apache.commons.lang.StringEscapeUtils.unescapeJava(...);
The actual writing to accumulo looks like this:
Mutation mut = new Mutation(new Text(checkSum));
Value val = new Value(new Text(filename).getBytes());
long timestamp = System.currentTimeMillis();
mut.put(new Text(colFam), new Text(EMPTY_BYTES), timestamp, val);
but nothing unusual showed up there (perhaps \x00 isn't escaped)? But then if I do a scan on my table in accumulo, there will be one or more \x00 in the file name.
The problem this seems to cause is that I return that string within XML when I retrieve a list of files (where it shows up) and pass that back to the browser, the the XSL that is supposed to render the information in the XML no longer works when there's these extra characters (not sure why that is the case either).
In chrome, for the response on these calls, I see that there's three red dots after the file name, and when I hover over it, \u0 pops up (which I think is a different representation of 0/null?).
Anyway, I'm just trying to figure out why this happens, or at the very least, how I can filter out \x00 characters before returning the file in Java. any ideas?

You are likely incorrectly using the Hadoop Text class -- this is not an error with Accumulo. Specifically, you make the mistake in your above example:
Value val = new Value(new Text(filename).getBytes());
You must adhere to the length of provided by the Text class. See the Text javadoc for more information. If you're using Hadoop-2.2.0, you can use the provided copyBytes method on Text. If you're on older version of Hadoop where this method doesn't yet exist, you can use something like the ByteBuffer class or the System.arraycopy method to get a copy of the byte[] with the proper limits enforced.