Java notes: I/O

First, the flow

Java implements I/O through a stream, which is an abstraction that can produce or consume information.

Java defines two types of streams:

• BYTE stream: Handles input and output of bytes, such as reading and writing binary data.
• Character Stream: Handles the input and output of characters.

All I/O at the bottom is still byte-oriented, and the character stream knowledge provides a more efficient way to process characters.

Second, the Word throttle class

Bufferedinputstream Bufferedoutputstream	Buffered input stream Buffered output stream
Bytearrayinputstream Bytearrayoutputstream	Reading the input stream of a byte array Writes the output stream of a byte array
DataInputStream DataOutputStream	Input stream for methods that read standard data types Output stream for methods that write to standard data types
FileInputStream FileInputStream	Read the input stream of a file Output stream written to file
InputStream OutputStream	Abstract class describing stream input Abstract class describing stream output
FilterInputStream Filteroutputstream	Implement InputStream Implement OutputStream
ObjectInputStream ObjectOutputStream	The input stream of the object The output stream of the object
PipedInputStream PipedOutputStream	Input piping Output piping
PrintStream	Output streams that contain print and println
Pushbackinputstream	Allow bytes to return an input stream
Sequenceinputstream	An input stream composed of multiple input streams that are read sequentially

Third, character Stream class

BufferedReader BufferedWriter	Buffered input character stream Buffered output character stream
CharArrayReader Chararraywriter	An input stream that reads content from a character array Output stream that writes content to a character array
FileReader FileWriter	Read the input stream of a file Output stream written to file
FilterReader Filterwriter	Filtered Reader Filters for Writers
InputStreamReader OutputStreamWriter	Input stream to convert bytes to characters Output stream to convert characters to bytes
StringReader StringWriter	Input stream to read content from a string Output stream to write content to a string
Pipedreader PipedWriter	Input piping Output piping
Reader Writer	Abstract class describing the character stream input Abstract class describing the output of a character stream
PrintWriter	Output streams that contain print and println
Pushbackreader	Allow characters to return an input stream
LineNumberReader	Input streams that support row operations

Iv. pre-defined flow

Predefined flows contained by system

• System.out: Standard output stream, PrintStream type object.
• System.err: Standard error stream, PrintStream type object.
• System.in: Standard input stream, InputStream type object.

V. Console

ImportJava.io.BufferedReader;Importjava.io.IOException;ImportJava.io.InputStreamReader;ImportJava.io.PrintWriter;classSolution { Public Static voidMain (string[] args)throwsIOException {BufferedReader reader=NewBufferedReader (NewInputStreamReader (system.in)); Charc = (Char) Reader.read ();//Get characterSystem.out.write (c); String Str= Reader.readline ();//reading a stringPrintWriter writer =NewPrintWriter (System.out,true);    Writer.println (str); }}

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Vi. Read and write files

ImportJava.io.FileInputStream;Importjava.io.FileNotFoundException;ImportJava.io.FileOutputStream;Importjava.io.IOException;classSolution {Staticstring Read (string fileName) {fileinputstream fin=NULL; StringBuilder Builder=NewStringBuilder (); Try{fin=NewFileInputStream (fileName); inti;  Do{i= Fin.read ();//Read bytes                if(I! =-1)//-1 means end of file reachedBuilder.append ((Char) (i); }  while(I! =-1); } Catch(FileNotFoundException exc) {System.out.println ("Cannot open File"); } Catch(IOException exc) {System.out.println ("Cannot read file"); } finally {            Try {                if(Fin! =NULL) Fin.close (); } Catch(IOException exc) {System.out.println ("Cannot close file"); }        }        returnbuilder.tostring (); }    Static voidWrite (string fileName, string content) {FileOutputStream Fout=NULL; Try{fout=NewFileOutputStream (fileName);  for(inti = 0; I < content.length (); i++) Fout.write (int) Content.charat (i));//Write Bytes}Catch(FileNotFoundException exc) {System.out.println ("Cannot open File"); } Catch(IOException exc) {System.out.println ("Cannot write file"); } finally {            Try {                if(Fout! =NULL) Fout.close (); } Catch(IOException exc) {System.out.println ("Cannot close file"); }        }    }}

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Automatically closes the file, leaving the code block implicitly calling the Close method to close the stream associated object.

ImportJava.io.FileInputStream;Importjava.io.FileNotFoundException;Importjava.io.IOException;classSolution { Public Static voidMain (string[] args) {Try(FileInputStream fin =NewFileInputStream ("file.txt")) {            inti;  Do{i=Fin.read (); if(I! =-1) System.out.print (Char) (i); }  while(I! =-1); } Catch(FileNotFoundException exc) {System.out.println ("Cannot open File"); } Catch(IOException exc) {System.out.println ("Cannot read file"); }    }}

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Java notes: I/O