bufferedwriter

Write file using BufferedWriter in Java [duplicate]

由 故事扮演 提交于 2019-11-28 04:08:09
问题 This question already has answers here : BufferedWriter not writing everything to its output file (8 answers) Closed 4 years ago . I am doing a lab where we have to read in an external file, take some statistics on the data, and then create and write a new file with the stats. Everything in my program works except for writing the file, which I cannot understand why my method won't work. BufferedWriter writer; public void writeStats(int word, int numSent, int shortest, int longest, int average

Is PrintWriter buffered?

由 喜欢而已 提交于 2019-11-28 00:45:53
问题 I know that the PrintWriter is really good if we want to write formatted data, and I also know the use of BufferedWriter to improve IO performance. But I tried something like this, PrintWriter pw = new PrintWriter(System.out); pw.println("Statement 1"); pw.println("Statement 2"); //pw.flush(); I observed that when the flush method is commented there is no output, but when I uncomment it, I get the desired output. This is only possible if the PrintWriter is buffered. If so, then what is the

FileWrite BufferedWriter and PrintWriter combined

由 老子叫甜甜 提交于 2019-11-27 19:28:39
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 BufferedWriter (fw); PrintWriter outFile = new PrintWriter (bw); Presumably they're using a FileWriter

Writing a file using multiple threads

由 两盒软妹~` 提交于 2019-11-27 07:55:26
I am trying to write a single huge file in Java using multiple threads. I have tried both FileWriter and bufferedWriter classes in Java. The content being written is actually an entire table (Postgres) being read using CopyManager and written. Each line in the file is a single tuple from the table and I am writing 100s of lines at a time. Approach to write: The single to-be-written file is opened by multiple threads in append mode. Each thread thereafter tries writing to the file file. Following are the issues I face: Once a while, the contents of the file gets overwritten i.e: One line

Bufferedwriter works, but file empty?

由 主宰稳场 提交于 2019-11-27 07:25:46
问题 I have the following code: CSVmaker(LinkedList data) { String [] myLines = makeStrings(data); // for (int k = 0; k<myLines.length; k++) // System.out.println(myLines[]); this.file = new File("rawdata.csv"); try { BufferedWriter buff = new BufferedWriter(new FileWriter(file)); for (int i = 0; i<myLines.length; i++){ buff.write(myLines[i]); buff.newLine(); System.out.println("done"); } } catch (IOException ex) { System.out.println("except"); } } No, I checked for the contents of myLines, these

Read and Write Text in ANSI format

由 元气小坏坏 提交于 2019-11-27 03:57:32
Please have a look at the following code import java.io.*; public class CSVConverter { private File csvFile; private BufferedReader reader; private StringBuffer strBuffer; private BufferedWriter writer; int startNumber = 0; private String strString[]; public CSVConverter(String location, int startNumber) { csvFile = new File(location); strBuffer = new StringBuffer(""); this.startNumber = startNumber; //Read try { reader = new BufferedReader(new FileReader(csvFile)); String line = ""; while((line=reader.readLine())!=null) { String[] array = line.split(","); String inputQuery = "insertQuery["

in what way is java.net.Socket threadsafe?

由 我只是一个虾纸丫 提交于 2019-11-27 03:25:44
问题 I have a Socket that I am both reading and writing to, via BufferedReaders and BufferedWriters. I'm not sure which operations are okay to do from separate threads. I would guess that writing to the socket from two different threads at the same time is a bad idea. Same with reading off the socket from two different threads at the same time. What about reading on one thread while writing on another? I ask because I want to have one thread blocked for a long time on a read as it waits for more

Java: CSV File Easy Read/Write

由 ↘锁芯ラ 提交于 2019-11-26 14:47:44
问题 I'm working on a program that requires quick access to a CSV comma-delimited spreadsheet file. So far I've been able to read from it easily using a BufferedReader. However, now I want to be able to edit the data it reads, then export it BACK to the CSV. The spreadsheet contains names, phone numbers, email addresses, etc. And the program lists everyone's data, and when you click on them it brings up a page with more detailed information, also pulled from the CSV. On that page you can edit the

how to write an array to a file Java

由 冷暖自知 提交于 2019-11-26 09:09:38
问题 I have been trying to write an array to a file. I know how to write integers or String to a file but to bring an array confuses me. I am using this right now: public static void write (String file, int[]x) throws IOException{ BufferedWriter outputWriter = null; outputWriter = new BufferedWriter(new FileWriter(filename)); outputWriter.write(\"hi\");// Here I know i cant just write x[0] or anything. Do i need //to loop in order to write the array? outputWriter.newLine(); outputWriter.flush();

BufferedWriter not writing everything to its output file

由 隐身守侯 提交于 2019-11-25 22:47:12
问题 I have a Java program that reads some text from a file, line by line, and writes new text to an output file. But not all the text I write to my BufferedWriter appears in the output file after the program has finished. Why is that? The details: the program takes a CSV text document and converts it into SQL commands to insert the data into a table. The text file has more than 10000 lines which look similar to following: 2007,10,9,1,1,1006134,19423882 The program seems to work fine except it
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