java-io

问题 I read that new File("path") doesn't physically create a file on disk. Though in the API it is said: Instances of this class may or may not denote an actual file-system object such as a file or a directory. If it does denote such an object then that object resides in a partition. A partition is an operating system-specific portion of storage for a file system. A single storage device (e.g. a physical disk-drive, flash memory, CD-ROM) may contain multiple partitions. So I'm curious if it is

问题 I am having trouble understanding this comment from the Java serialization documentation: Array classes cannot declare an explicit serialVersionUID, so they always have the default computed value, but the requirement for matching serialVersionUID values is waived for array classes. Maybe I am unable to understand the obvious, however, I haven't figured why would I need to do this? 回答1: I think that the answer to your question is to read up on serialVersionUID. In particular, you often want to

问题 Assumption: Stream s are lazy, hence the following statement does not load the entire children of the directory referenced by the path into memory; instead it loads them one by one, and after each invocation of forEach , the directory referenced by p is eligible for garbage collection, so its file descriptor should also become closed: Files.list(path).forEach(p -> absoluteFileNameQueue.add( p.toAbsolutePath().toString() ) ); Based on this assumption, I have implemented a breadth-first file

问题 I have a file which has characters like: " Joh 1:1 ஆதியிலே வார்த்தை இருந்தது, அந்த வார்த்தை தேவனிடத்திலிருந்தது, அந்த வார்த்தை தேவனாயிருந்தது. " www.unicode.org/charts/PDF/U0B80.pdf‎ When I use the following code: bufferedWriter = new BufferedWriter (new OutputStreamWriter(System.out, "UTF8")); The output is boxes and other weird characters like this: "�P�^����O֛���;�<�aYՠ؛" Can anyone help? these are the complete codes: File f=new File("E:\\bible.docx"); Reader decoded=new InputStreamReader

问题 Ok, say I have a text file called "people.txt", and it contains the following information: 1 adam 20 M 2 betty 49 F 3 charles 9 M 4 david 22 M 5 ethan 41 M 6 faith 23 F 7 greg 22 M 8 heidi 63 F Basically, the first number is the ID of the person, then comes the person's name, age and gender. Say I want to replace line 2, or the person with ID number 2 with different values. Now, I know I cant use RandomAccessFile for this because the names are not always the same number of bytes, neither are

问题 I am getting this error when I try to open a file: java.io.FileNotFoundException: D:\Portable%20Programs\Android%20Development\workspace3\XXX-desktop\bin\World_X.fr (The system cannot find the path specified) at java.io.FileInputStream.open(Native Method) at java.io.FileInputStream.<init>(Unknown Source) at java.util.Scanner.<init>(Unknown Source) The file is existing in the directory but I am still getting this error. However when I copy the same file in the Eclipse workspace Project src

问题 we'd defend against the code crackers who can operate on the whole operation system who may read the encoded class-file via "java.io" and save the copy we'd protect java-based application's intellectual property this requirement was raised by several customers, so it has realistic value. Simplex Java-JDK-JVM solution like securityManager without native code/tool can NOT be accepted because it's easy to be bypassed, since cracker have the admin privilege on the OS in this scenario. 回答1: You

问题 I'm apparently facing an infinite loop on while(input.hasNext()) , as in following code File file = new File("data.txt"); Scanner input = new Scanner(file); int sum = 0; while (input.hasNext()) { if (input.hasNextInt()) { sum += input.nextInt(); } } System.out.println(sum); Some related questions explain why it always returns true if input stream is System.in , however I'm scanning through a File . Please let me know where I'm going wrong. I'm attempting to calculate the sum of unique integer

问题 Please move down to the 2nd update. I didn't want to change the previous context of this question. I'm using wkhtmltoimage from a Java app. The standard way of using it is - path-to-exe http://url.com/ image.png . According to their docs, if we write a - instead of an input URL, the input shifts to STDIN. I'm starting the process using ProcessBuilder - ProcessBuilder pb = new ProcessBuilder(exe_path, " - ", image_save_path); Process process = pb.start(); Now I'm unable to figure out how to

问题 Im making a simple TCP/IP Socket app Whats the different between doing this: DataInputStream in = new DataInputStream(clientSocket.getInputStream()); byte[] buffer = new byte[100]; in.readFully(buffer); versus doing this: DataInputStream in = new DataInputStream(clientSocket.getInputStream()); byte[] buffer = new byte[100]; in.read(buffer); I had a look at the documentation, they have the same exact description. readFully() and read() So can I assume its the same thing? 回答1: The Javadoc for