writer

问题 I am not sure whether I need to call Flush() on the used objects if I write something like this: using (FileStream...) using (CryptoStream...) using (BinaryWriter...) { // do something } Are they always automatically flushed? When does the using statement flush them and when it doesn’t (if that can happen)? 回答1: As soon as you leave the using block’s scope, the stream is closed and disposed. The Close() calls the Flush(), so you should not need to call it manually. 回答2: It varies, Stream by

问题 When I try to use JpCap Writer to save packets to a file, it causes JVM to crash. Code: captor=JpcapCaptor.openDevice(interfaceList[interfaceNumber], 65535, true, 20); captor.setFilter("ip and tcp",true); JpcapWriter writer=JpcapWriter.openDumpFile(captor,"write.txt"); for(int i=0;i<10;i++){ Packet packet=captor.getPacket(); writer.writePacket(packet); } writer.close(); Crash info: # # A fatal error has been detected by the Java Runtime Environment: # # SIGSEGV (0xb) at pc=0x00007f283105953a,

问题 the following code leave a empty white line at the end of the txt file. how can i not have the writerows not terminate the last line? with open(fname, 'wb') as myFile: # Start the CSV Writer wr = csv.writer(myFile, delimiter=',', dialect='excel') wr.writerows(rows) # Close the file. myFile.close() 回答1: Firstly, since you are using with open as myFile you don't need myFile.close() , that is done automatically when you remove the indent. Secondly, if you are willing to add another part to your

问题 I have multiple lists with each list containing strings that I want to fill in a csv table. I want each list to be a separate column of data in its respective column header. The header row is the same sequence as the outrow variable. With the code below it simply just fills in the first column with all the data from all the lists. #outrow = (Layer,RasterCatalog,ShapeFile,Text,Terrain,GroupLayer,Locator,MapDocument,Toolbox,DbaseTable,RasterDataset) #formats = (['Layer','RasterCatalog',

问题 i'm trying to call a JsonWriter method to add something to test.json after receiving wifi information, but after it successful write the file, the file still empty.Here are the codes. OnReceive @Override public void onReceive(Context c, Intent i) { if (i.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) { dbhelp = new DataBaseHelper(c); wifilist = new ArrayList<ScanResult>(); wifilist = ((WifiManager) c.getSystemService(Context.WIFI_SERVICE)).getScanResults(); dialog.dismiss();

问题 In Log4j there was a WriterAppender that made it possible to write the logs to a Writer . I need the same functionality in Log4j2 , but I haven't found an option to do this yet. Does anyone know how to achieve the same with Log4j2 ? 回答1: If there is not an existing appender that serves your needs, create a custom appender plugin. I put together a quick example. package com.logging; import org.apache.logging.log4j.core.Filter; import org.apache.logging.log4j.core.Layout; import org.apache

问题 I want to write one single bit to a binary file. using (FileStream fileStream = new FileStream(@"myfile.bin", FileMode.Create)) using (BinaryWriter binaryWriter = new BinaryWriter(fileStream)) { binaryWriter.Write((bool)10); } Something like binaryWriter.Write((bit)1); When I use binaryWriter.Write((bool)1) the file has one byte, but I want to write one single bit. Is this possible? 回答1: You cannot store only 1 bit in a file. Almost all modern filesystems and hardware store data in segments

问题 I am writing to csv in python, and I was wondering why my output files are blank when the program completes running. First off, here is my code: reader = csv.reader(open(location, 'rU'), delimiter = ',', quotechar = '"') writer = csv.writer(open('temp.csv', 'wb'), delimiter = ',', quotechar = '"') writer.writerow(["test", "test", "test", "test", "test", "test", "test"]) count = 0 for row in reader: if count != 0 and count < len(split): writer.writerow([row[0], row[1], row[2], row[3], row[4],

问题 I know that writers should be used instead of outputstreams when writing text, but still I don't understand why there are extra characters in the file outputStream.txt after running this program: public static void main(String[] args) throws FileNotFoundException, IOException { ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(new File("C:\\Data\\tmp\\outputStream.txt"))); oos.writeObject("SomeObject"); oos.writeUTF("SomeUTF"); oos.flush(); oos.close(); BufferedWriter

问题 It was claimed in Validations in Haskell that use of a Writer guarantees right-associative concatenation. However, this example seems to show otherwise. What's the correct answer? {-# LANGUAGE OverloadedStrings #-} import Control.Monad.Writer import Data.String data TM = TMempty | TMappend TM TM | TMfromString String instance IsString TM where fromString = TMfromString instance Monoid TM where mempty = TMempty mappend = TMappend instance Show TM where showsPrec d TMempty = showString "\"\""