Category: 09. Java.io package

Introduction

The Java.io.Writer class is a abstract class for writing to character streams.

Class declaration

Following is the declaration for Java.io.Writer class −

public abstract class Writer
   extends Object
  implements Appendable, Closeable, Flushable

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Field

Following are the fields for Java.io.Writer class −

• protected Object lock − This is the object used to synchronize operations on this stream.

Class constructors

Sr.No.	Constructor & Description
1	protected Writer()This creates a new character-stream writer whose critical sections will synchronize on the writer itself.
2	protected Writer(Object lock)This creates a new character-stream writer whose critical sections will synchronize on the given object.

Class methods

Sr.No.	Method & Description
1	Writer append(char c)This method appends the specified character to this writer.
2	Writer append(CharSequence csq)This method appends the specified character sequence to this writer.
3	Writer append(CharSequence csq, int start, int end)This method appends a subsequence of the specified character sequence to this writer.
4	abstract void close()This method loses the stream, flushing it first.
5	abstract void flush()This method flushes the stream.
6	void write(char[] cbuf)This method writes an array of characters.
7	abstract void write(char[] cbuf, int off, int len)This method writes a portion of an array of characters.
8	void write(int c)This method writes a single character.
9	void write(String str)This method writes a string.
10	void write(String str, int off, int len)This method writes a portion of a string.

Methods inherited

This class inherits methods from the following classes −

• Java.io.Object

Introduction

The Java.io.StringWriter class is a character stream that collects its output in a string buffer, which can then be used to construct a string.Closing a StringWriter has no effect. The methods in this class can be called after the stream has been closed without generating an IOException.

Class declaration

Following is the declaration for Java.io.StringWriter class −

public class StringWriter
  extends Writer

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Field

Following are the fields for Java.io.StringWriter class −

• protected Object lock − This is the object used to synchronize operations on this stream.

Class constructors

Sr.No.	Constructor & Description
1	StringWriter()This creates a new string writer using the default initial string-buffer size.
2	StringWriter(int initialSize)This creates a new string writer using the specified initial string-buffer size.

Class methods

Sr.No.	Method & Description
1	StringWriter append(char c)This method appends the specified character to this writer.
2	StringWriter append(CharSequence csq)This method appends the specified character sequence to this writer.
3	StringWriter append(CharSequence csq, int start, int end)This method appends a subsequence of the specified character sequence to this writer.
4	void close()Closing a StringWriter has no effect.
5	void flush()This method flush the stream.
6	StringBuffer getBuffer()This method return the string buffer itself.
7	String toString()This method return the buffer’s current value as a string.
8	void write(char[] cbuf, int off, int len)This method write a portion of an array of characters.
9	void write(int c)This method write a single character.
10	void write(String str)This method writes a string.
11	void write(String str, int off, int len)This method writes a portion of a string.

Methods inherited

This class inherits methods from the following classes −

• Java.io.Writer
• Java.io.Object

Introduction

The Java.io.StringReader class is a character stream whose source is a string.

Class declaration

Following is the declaration for Java.io.StringReader class −

public class StringReader
   extends Reader

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Field

Following are the fields for Java.io.StringReader class −

• protected Object lock − This is the object used to synchronize operations on this stream.

Class constructors

Sr.No.	Constructor & Description
1	StringReader(String s)This creates a new string reader.

Class methods

Sr.No.	Method & Description
1	void close()This method closes the stream and releases any system resources associated with it.
2	void mark(int readAheadLimit)This method marks the present position in the stream.
3	boolean markSupported()This method tells whether this stream supports the mark() operation, which it does.
4	int read()This method reads a single character.
5	int read(char[] cbuf, int off, int len)This method reads characters into a portion of an array.
6	boolean ready()This method tells whether this stream is ready to be read.
7	void reset()This method resets the stream to the most recent mark, or to the beginning of the string if it has never been marked.
8	long skip(long ns)This method skips the specified number of characters in the stream.

Methods inherited

This class inherits methods from the following classes −

• Java.io.Reader
• Java.io.Object

Introduction

The Java.io.StringBufferInputStream class allows an application to create an input stream in which the bytes read are supplied by the contents of a string. Applications can also read bytes from a byte array by using a ByteArrayInputStream.Only the low eight bits of each character in the string are used by this class.

This class has been deprecated by Oracle and should not be used any more.

Class declaration

Following is the declaration for Java.io.StringBufferInputStream class −

public class StringBufferInputStream
   extends InputStream

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Field

Following are the fields for Java.io.StringBufferInputStream class −

• protected String buffer − This is the string from which bytes are read.
• protected int count − This is the number of valid characters in the input stream buffer.
• protected int pos − This is the index of the next character to read from the input stream buffer.

Class constructors

Sr.No.	Constructor & Description
1	StringBufferInputStream(String s)This creates a string input stream to read data from the specified string.

Class methods

Sr.No.	Method & Description
1	int available()This method returns the number of bytes that can be read from the input stream without blocking.
2	int read()This method reads the next byte of data from this input stream.
3	int read(byte[] b, int off, int len)This method reads up to len bytes of data from this input stream into an array of bytes.
4	void reset()This method resets the input stream to begin reading from the first character of this input stream’s underlying buffer.
5	long skip(long n)This method skips n bytes of input from this input stream.

Methods inherited

This class inherits methods from the following classes −

• Java.io.InputStreams
• Java.io.Object

Introduction

The Java.io.StreamTokenizer class takes an input stream and parses it into “tokens”, allowing the tokens to be read one at a time. The stream tokenizer can recognize identifiers, numbers, quoted strings, and various comment styles.

Class declaration

Following is the declaration for Java.io.StreamTokenizer class −

public class StreamTokenizer
   extends Object

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Field

Following are the fields for Java.io.StreamTokenizer class −

• double 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.
• static int TT_EOF − A constant indicating that the end of the stream has been read.
• static int TT_EOL − A constant indicating that the end of the line has been read.
• static int TT_NUMBER − A constant indicating that a number token has been read.
• static int TT_WORD − A constant indicating that a word token has been read.
• int ttype − After a call to the nextToken method, this field contains the type of the token just read.

Class constructors

Sr.No.	Constructor & Description
1	StreamTokenizer(Reader r)This creates a tokenizer that parses the given character stream.

Class methods

Sr.No.	Method & Description
1	void commentChar(int ch)Specified that the character argument starts a single-line comment.
2	void eolIsSignificant(boolean flag)This method determines whether or not ends of line are treated as tokens.
3	int lineno()This method returns the current line number.
4	void lowerCaseMode(boolean fl)This method determines whether or not word token are automatically lowercased.
5	int nextToken()This method parses the next token from the input stream of this tokenizer.
6	void ordinaryChar(int ch)This method specifies that the character argument is “ordinary” in this tokenizer.
7	void ordinaryChars(int low, int hi)This method specifies that all characters c in the range low <= c <= high are “ordinary” in this tokenizer.
8	void parseNumbers()This method specifies that numbers should be parsed by this tokenizer.
9	void pushBack()This method causes the next call to the nextToken method of this tokenizer to return the current value in the ttype field, and not to modify the value in the nval or sval field.
10	void quoteChar(int ch)This method specifies that matching pairs of this character delimit string constants in this tokenizer.
11	void resetSyntax()This method resets this tokenizer’s syntax table so that all characters are “ordinary.” See the ordinaryChar method for more information on a character being ordinary.
12	void slashSlashComments(boolean flag)This method determines whether or not the tokenizer recognizes C++ style comments.
13	void slashStarComments(boolean flag)This method determines whether or not the tokenizer recognizes C style comments.
14	String toString()This method returns the string representation of the current stream token and the line number it occurs on.
15	void whitespaceChars(int low, int hi)This method specifies that all characters c in the range low <= c <= high are white space characters.
16	void wordChars(int low, int hi)This method specifies that all characters c in the range low <= c >= high are word constituents.

Methods inherited

This class inherits methods from the following classes −

• Java.io.Object

Introduction

The Java.io.SerializablePermission class is for Serializable permissions. A SerializablePermission contains a name (also referred to as a “target name”) but no actions list; you either have the named permission or you don’t.The target name is the name of the Serializable permission.

Class declaration

Following is the declaration for Java.io.SerializablePermission class −

public final class SerializablePermission
   extends BasicPermission

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Class constructors

Sr.No.	Constructor & Description
1	SerializablePermission(String name)This creates a new SerializablePermission with the specified name.
2	SerializablePermission(String name, String actions)This creates a new SerializablePermission object with the specified name.

Methods inherited

This class inherits methods from the following classes −

• Java.io.BasicPermission
• Java.io.Permission
• Java.io.Object

Introduction

The Java.io.SequenceInputStream class represents the logical concatenation of other input streams. It starts out with an ordered collection of input streams and reads from the first one until end of file is reached, whereupon it reads from the second one, and so on, until end of file is reached on the last of the contained input streams.

Class declaration

Following is the declaration for Java.io.SequenceInputStream class −

public class SequenceInputStream
   extends InputStream

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Class constructors

Sr.No.	Constructor & Description
1	SequenceInputStream(Enumeration<? extends InputStream> e)This initializes a newly created SequenceInputStream by remembering the argument, which must be an Enumeration that produces objects whose run-time type is InputStream.
2	SequenceInputStream(InputStream s1, InputStream s2)This initializes a newly created SequenceInputStream by remembering the two arguments, which will be read in order, first s1 and then s2, to provide the bytes to be read from this SequenceInputStream.

Class methods

Sr.No.	Method & Description
1	int available()This method returns an estimate of the number of bytes that can be read (or skipped over) from the current underlying input stream without blocking by the next invocation of a method for the current underlying input stream.
2	void close()This method closes this input stream and releases any system resources associated with the stream.
3	int read()This method reads the next byte of data from this input stream.
4	int read(byte[] b, int off, int len)This method reads up to len bytes of data from this input stream into an array of bytes.

Methods inherited

This class inherits methods from the following classes −

• Java.io.InputStream
• Java.io.Object

Introduction

The Java.io.Reader class is a abstract class for reading character streams.

Class declaration

Following is the declaration for Java.io.Reader class −

public class Reader
   extends Object
  implements DataOutput, DataInput, Closeable

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Field

Following are the fields for Java.io.Reader class −

• protected Object lock − This is the object used to synchronize operations on this stream.

Class constructors

Sr.No.	Constructor & Description
1	protected Reader()This creates a new character-stream reader whose critical sections will synchronize on the reader itself.
2	protected Reader(Object lock)This creates a new character-stream reader whose critical sections will synchronize on the given object.

Class methods

Sr.No.	Method & Description
1	abstract void close()This method closes the stream and releases any system resources associated with it.
2	void mark(int readAheadLimit)This method marks the present position in the stream.
3	boolean markSupported()This method tells whether this stream supports the mark() operation.
4	int read()This method reads a single character.
5	int read(char[] cbuf)This method reads characters into an array.
6	abstract int read(char[] cbuf, int off, int len)This method reads characters into a portion of an array.
7	int read(CharBuffer target)This method attempts to read characters into the specified character buffer.
8	boolean ready()This method tells whether this stream is ready to be read.
9	void reset()This method resets the stream.
10	long skip(long n)This method skips characters.

Methods inherited

This class inherits methods from the following classes −

• Java.io.Object

Introduction

The Java.io.RandomAccessFile class file behaves like a large array of bytes stored in the file system.Instances of this class support both reading and writing to a random access file.

Class declaration

Following is the declaration for Java.io.RandomAccessFile class −

public class RandomAccessFile
   extends Object
  implements DataOutput, DataInput, Closeable

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Class constructors

Sr.No.	Constructor & Description
1	RandomAccessFile(File file, String mode)This creates a random access file stream to read from, and optionally to write to, the file specified by the File argument.
2	RandomAccessFile(File file, String mode)This creates a random access file stream to read from, and optionally to write to, a file with the specified name.

Class methods

Sr.No.	Method & Description
1	void close()This method Closes this random access file stream and releases any system resources associated with the stream.
2	FileChannel getChannel()This method returns the unique FileChannel object associated with this file.
3	FileDescriptor getFD()This method returns the opaque file descriptor object associated with this stream.
4	long getFilePointer()This method returns the current offset in this file.
5	long length()This method returns the length of this file.
6	int read()This method reads a byte of data from this file.
7	int read(byte[] b)This method reads up to b.length bytes of data from this file into an array of bytes.
8	int read(byte[] b, int off, int len)This method reads up to len bytes of data from this file into an array of bytes.
9	boolean readBoolean()This method reads a boolean from this file.
10	byte readByte()This method reads a signed eight-bit value from this file.
11	char readChar()This method reads a character from this file.
12	double readDouble()This method reads a double from this file.
13	float readFloat()This method reads a float from this file.
14	void readFully(byte[] b)This method reads b.length bytes from this file into the byte array, starting at the current file pointer.
15	void readFully(byte[] b, int off, int len)This method reads exactly len bytes from this file into the byte array, starting at the current file pointer.
16	int readInt()This method reads a signed 32-bit integer from this file.
17	String readLine()This method reads the next line of text from this file.
18	long readLong()This method reads a signed 64-bit integer from this file.
19	short readShort()This method reads a signed 16-bit number from this file.
20	int readUnsignedByte()This method reads an unsigned eight-bit number from this file.
21	int readUnsignedShort()This method reads an unsigned 16-bit number from this file.
22	String readUTF()This method reads in a string from this file.
23	void seek(long pos)This method sets the file-pointer offset, measured from the beginning of this file, at which the next read or write occurs.
24	void setLength(long newLength)This method sets the length of this file.
25	int skipBytes(int n)This method attempts to skip over n bytes of input discarding the skipped bytes.
26	void write(byte[] b)This method writes b.length bytes from the specified byte array to this file, starting at the current file pointer.
27	void write(byte[] b, int off, int len)This method writes len bytes from the specified byte array starting at offset off to this file.
28	void write(int b)This method writes the specified byte to this file.
29	void writeBoolean(boolean v)This method writes a boolean to the file as a one-byte value.
30	void writeByte(int v)This method writes a byte to the file as a one-byte value.
31	void writeBytes(String s)This method writes the string to the file as a sequence of bytes.
32	void writeChar(int v)This method writes a char to the file as a two-byte value, high byte first.
33	void writeChars(String s)This method writes a string to the file as a sequence of characters.
34	void writeDouble(double v)This method converts the double argument to a long using the doubleToLongBits method in class Double, and then writes that long value to the file as an eight-byte quantity, high byte first.
35	void writeFloat(float v)This method converts the float argument to an int using the floatToIntBits method in class Float, and then writes that int value to the file as a four-byte quantity, high byte first.
36	void writeInt(int v)This method writes an int to the file as four bytes, high byte first.
37	void writeLong(long v)This method writes a long to the file as eight bytes, high byte first.
38	void writeShort(int v)This method writes a short to the file as two bytes, high byte first.
39	void writeUTF(String str)This method writes a string to the file using modified UTF-8 encoding in a machine-independent manner.

Methods inherited

This class inherits methods from the following classes −

• Java.io.Object

Introduction

The Java.io.PushbackReader class is a character-stream reader that allows characters to be pushed back into the stream.

Class declaration

Following is the declaration for Java.io.PushbackReader class −

public class PushbackReader
   extends FilterReader

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Field

Following are the fields for Java.io.PushbackReader class −

• protected Reader in − This is the character-input stream.
• protected Object lock − This is the object used to synchronize operations on this stream.

Class constructors

Sr.No.	Constructor & Description
1	PushbackReader(Reader in)This creates a new pushback reader with a one-character pushback buffer.
2	PushbackReader(Reader in, int size)This creates a new pushback reader with a pushback buffer of the given size.

Class methods

Sr.No.	Method & Description
1	void close()This method closes the stream and releases any system resources associated with it.
2	void mark(int readAheadLimit)This method marks the present position in the stream.
3	boolean markSupported()This method tells whether this stream supports the mark() operation, which it does not.
4	int read()This method reads a single character.
5	int read(char[] cbuf, int off, int len)This method reads characters into a portion of an array.
6	boolean ready()This method tells whether this stream is ready to be read.
7	void reset()This method resets the stream.
8	long skip(long n)This method skips characters.
9	void unread(char[] cbuf)This method pushes back an array of characters by copying it to the front of the pushback buffer.
10	void unread(char[] cbuf, int off, int len)This method pushes back a portion of an array of characters by copying it to the front of the pushback buffer.
11	void unread(int c)This method pushes back a single character by copying it to the front of the pushback buffer.

Methods inherited

This class inherits methods from the following classes −

• Java.io.Reader
• Java.io.Object