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.