bufferedwriter

问题 I have a string that I format with the System.out.format() method, I do something like : System.out.format("I = %3d var = %9.6f", i, myVar); but when I try to write this formatted string into a file, I only get something like "java.io.PrintStream@84fc8d" in it. After looking into the documentation understood that this method is a little like System.out.print() and just return a PrintStream to display (in console for example), so I tried converting it with .toString or String.valueOf() but I

问题 I am pretty new to java and wanted to understand the reasoning why this does not work. Why does the sys out print work perfectly, but the buffered writer does not? I am just trying to understand the difference between the two/ //print the input matrix to the user System.out.println("Matrix read: "); System.out.println("------------------" + "---------------------"); for (int i = 0; i < size; i++) { for (int j = 0; j < size; j++) { System.out.printf("%5d ", a[i][j]); bw.write(a[i][j]); bw

来源： https://stackoverflow.com/questions/25571051/count-the-bytes-written-to-file-via-bufferedwriter-formed-by-gzipoutputstream

问题 I am trying to write a script that will run a .exe program 4 times with different parameters. I created one thread for each .exe run. Each thread will write an output file. My problem is that, it should write in parallel, but as you can you see on the screenshot below, the file write one after another. How should this be resolved? Here's the main method: public static void main (String args[]) { ExecutorService executor = Executors.newFixedThreadPool(4); executor.execute(new RunnableReader(

问题 I have a buffered writer that is writing to a text file. For some reason the writer stops writing a long string about half way through. Are there any known issues with using the buffered Writer in java? 回答1: Are you closing the writer? writer.close(); 回答2: Before writing large text into file, use obj_BufferedWriter.flush(). 来源： https://stackoverflow.com/questions/15623374/buffered-writer-java-limit-issues

问题 Ok so I am learning about I/O, and I found the following code in one of the slides. can someone please explain why there is a need to have a FileWrite, BufferedWriter and PrintWriter? I know BufferedWriter is to buffer the output and put it all at once but why would they use FileWriter and PrintWriter ? dont they pretty much do the same with a bit of difference in error handling etc? And also why do they pass bw to PrintWriter ? FileWriter fw = new FileWriter (file); BufferedWriter bw = new

问题 Ok so I am learning about I/O, and I found the following code in one of the slides. can someone please explain why there is a need to have a FileWrite, BufferedWriter and PrintWriter? I know BufferedWriter is to buffer the output and put it all at once but why would they use FileWriter and PrintWriter ? dont they pretty much do the same with a bit of difference in error handling etc? And also why do they pass bw to PrintWriter ? FileWriter fw = new FileWriter (file); BufferedWriter bw = new

问题 I have a method that is supposed to overwrite the current file with new content, however the FileWriter() is only appending the new content, not overwriting the old content. This is how my FileWriter is set up File file = new File(test.txt); BufferedWriter out; out = new BufferedWriter(new FileWriter(file, false)); Here is the save method //stuff is defined earlier and filled with the new content for the file ArrayList<String> stuff = new ArrayList<>(); //The actual save() method Object[]

问题 try { File file = new File(filePath+"usedcommands.txt"); if (!file.exists()) { file.createNewFile(); } FileWriter fw = new FileWriter(file.getAbsoluteFile()); BufferedWriter bw = new BufferedWriter(fw); bw.write(input+"\n"); bw.close(); } catch(Exception e) { System.out.println("can't write to usedcommands.txt..."); } I'm writing to a txt file, but every time I run through the writing process it overrides what is already written there. How can I change my code so this part of the program

问题 try { File file = new File(filePath+"usedcommands.txt"); if (!file.exists()) { file.createNewFile(); } FileWriter fw = new FileWriter(file.getAbsoluteFile()); BufferedWriter bw = new BufferedWriter(fw); bw.write(input+"\n"); bw.close(); } catch(Exception e) { System.out.println("can't write to usedcommands.txt..."); } I'm writing to a txt file, but every time I run through the writing process it overrides what is already written there. How can I change my code so this part of the program