• A stream is a sequence of data .

• A stream is a flowing sequence of characters.

Character and Byte Streams

File Class

• boolean exists():does the file exist

• boolean isFile(): is it a file

• boolean isDirectory: directory

• String[] list() :return the names of all files and directories in a directory

• String getName() :get the file or directory's nameString

• getPath() :get the file or directory's path

• list(): This method of Files class returns an array of strings naming the files and directories in the directory.

• file.listFiles(): This method  returns an array of  files  and folders present in the specified directory with their pathname.

• isDirectory(): It checks whether the file is a directory or not

public interface FilenameFilter • used to filter directory listings in the list

method of class File.• accept• public boolean accept(File dir, String name)

– Tests if a specified file should be included in a file list.

– Parameters:• dir - the directory in which the file was found.• name - the name of the file.

– Returns:–true if and only if the name should be included

in the file list; false otherwise.

–

• accept

• public boolean accept(File dir, String name) – Tests if a specified file should be included in a file

list. – Parameters:

• dir - the directory in which the file was found.• name - the name of the file.

– Returns:• true if and only if the name should be included in the file

list; false otherwise.

Class FileInputStream

• FileInputStream: – This class is a subclass of Inputstream class – reads bytes from a specified file name .

• Int read(): – method reads a byte or array of bytes from the file .– returns -1 when the end-of-file has been reached.

• This class throws FileNotFoundException

• Constructor:– FileInputstream(File filename);

FilterInputStream

• The FilterInputStream class is the superclass of all of the input stream classes that filter input.

• Each of the subclasses of FilterInputStreamprovides additional functionality.

• Data streams are filtered streams that perform binary I/O operation on primitive data type values ( boolean, char, byte, short, int, long, etc.) as well as on String values.

• If we need to work with data that is not represented as bytes or characters then you can use Data Streams.

• These streams filter an existing byte stream so that each primitive data types can be read from or written to the stream directly.

DataInputStream:

• allows you to read binary represented data of Java primitive data types from an underlying input stream in a machine-independent way

• DataoutputStream:• allows you to write binary represented data of

Java primitive data types reading from an underlying output stream in a machine-independent way. It writes only Java primitive data types and doesn't write the object values.

BufferedInputStream

• BufferedInputStream class that lets you read characters from a stream and stores it in an internal buffer .

• BufferedInputStream(InputStream inputStream) BufferedInputStream(InputStream inputStream, int bufSize)

BufferedoutputStream

• and buffers the output.

• BufferedOutputStream buf = new BufferedOutputStream(new FileOutputStream("file.java")); 

Random File Access

• Random access files permit nonsequential, or random, access to a file's contents .

• read(ByteBuffer) – Reads bytes into the buffer from the channel

• write(ByteBuffer) – Writes bytes from the buffer to the channel .

• Seek :sets the file pointer • getFilePointer () :reads filePointer.• Int skipBytes():Add n to the file pointer.

StreamTokenizer• Many times when reading an input stream of

characters, we need to parse it to see if what we are reading is a word or a number.  This process is called "tokenizing".

• The StreamTokenizer class takes an input stream and parses it into "tokens“, allowing the tokens to be read one at a time.

• StreamTokenizer breaks the input stream into tokens using whitespace as a delimiter.

• By default, Unicode characters \u0000 through \u0020 are considered whitespace. This encompasses things like space, tab, newline, etc

• If you want to change this list, you need to invoke the method whitespaceChars(int low, int high); all characters having Unicode values between low and high will be considered whitespace, in addition to the default set.

• int nval :If the current token is a number, this field contains the value of that number.

• String sval :If the current token is a word token, this field contains a string giving the characters of the word token.

• nextToken( )• next token is obtained from the input

stream by calling

• int ttype           After a call to the nextToken method, this field contains the type of the token just read.

• Int lineno()           Return the current line number.

•  void wordChars(int low, int hi)           Specifies that all characters c in the range low <= c <= high are word constituents.

• Void ordinaryChars(int low, int hi)           Specifies that all characters c in the range low <= c <= high are "ordinary" in this tokenizer.

• TT_EOF, TT_EOL, TT_NUMBER, and TT_WORD are four int constants

• TT_WORD indicates that the token is a word. • TT_NUMBER indicates that the token is a

number. • TT_EOL indicates that the end of line has been

read. The field can only have this value if the eolIsSignificant method has been called with the argument true.

• TT_EOF indicates that the end of the input stream has been reached.

• whitespaceChars( ) :Specify white space chars

StreamTokenizer

• eolIsSignificant( ) method to ensure that newline characters will be delivered as tokens, so we can count the number of lines as well as words.

• void eolIsSignificant(boolean eolFlag)• void wordChars(int start, int end)• start and end specify the range of valid

characters. characters in the range 33 to 255 are valid word characters.