La classe java.io.LineNumberInputStream és simplement una extensió del flux d'entrada que proporciona una facilitat addicional per mantenir el registre del número de línia actual.
Línia és una seqüència de bytes que acaba amb: 'r', és a dir, un caràcter de retorn de carro o un caràcter de nova línia: 'n' o un caràcter d'avançament de línia després del caràcter de retorn de carro.
Declaració:
public class LineNumberInputStream extends Reader
Constructors:
LineNumberInputStream(InputStream in) : Constructs a newline no. stream that reads it's input from the specified Input Stream.
Mètodes:
Sintaxi:
public int read() Parameters : ------- Return : int value representing the bytes in the range of '0 - 255'. return -1 indicating end of Input Stream. Exception: IOException : in case I/O error occurs
Implementació:
Java// Java program illustrating the working of read() method import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // LineNumberInputStream & FileInputStream initially null LineNumberInputStream geekline = null; FileInputStream geekinput = null; try{ char c; int a; // New InputStream : 'ABC' is created geekinput = new FileInputStream('ABC.txt'); geekline = new LineNumberInputStream(geekinput); // read() method returning Bytes of Input Stream as integer // '-1' indicating to read till end Of Input Stream while((a = geekline.read()) != -1) { // Since read() method returns Integer value // So we convert each integer value to char c = (char)a; System.out.print(c); } } catch(Exception e) { // In case of error e.printStackTrace(); System.out.println('ERROR Occurs '); } finally { // Closing the streams Once the End of Input Stream is reached if(geekinput != null) geekinput.close(); if(geekline != null) geekline.close(); } } }
Nota:
El codi Java següent no s'executarà aquí, ja que no podem accedir a cap fitxer a l'IDE en línia.
Per tant, copieu el programa al vostre sistema i executeu-lo allà.
El ABC.txt El fitxer utilitzat al programa conté:
Hello Geeks. Explaining read() method
Sortida:
Hello Geeks. Explaining read() method
Sintaxi:
public int getLineNumber() Parameters : ------- Return : no. of current line
Implementació:
Java// Java program illustrating the working of getLineNumber() method import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // LineNumberInputStream & FileInputStream initially null LineNumberInputStream geekline = null; FileInputStream geekinput = null; try { char c; int a b; // New InputStream : 'ABC' is created geekinput = new FileInputStream('ABC.txt'); geekline = new LineNumberInputStream(geekinput); while((a = geekline.read()) != -1) { // So we convert each integer value to char c = (char)a; // Use of getLineNumber() : to print line no. a = geekline.getLineNumber(); System.out.println(' At line : ' + a); System.out.print(c); } a = geekline.getLineNumber(); System.out.println(' at line: ' + a); } catch(Exception e) { // In case of error e.printStackTrace(); System.out.println('ERROR Occurs '); } finally { // Closing the streams Once the End of Input Stream is reached if(geekinput != null) geekinput.close(); if(geekline != null) geekline.close(); } } }
Nota:
El codi Java següent no s'executarà aquí, ja que no podem accedir a cap fitxer a l'IDE en línia.
Per tant, copieu el programa al vostre sistema i executeu-lo allà.
El ABC.txt El fitxer utilitzat al programa conté:
no. of lines
Sortida:
At line : 0 n At line : 0 o At line : 0 . At line : 0 At line : 0 o At line : 0 f At line : 1 At line : 1 l At line : 1 i At line : 1 n At line : 1 e At line : 1 s at line: 1
Sintaxi:
public int available() Parameters : ------- Return : returns the no. of bytes that can be read from the Input Stream. Exception: IOException : in case I/O error occurs
Implementació:
Java// Java program illustrating the working of available() method import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // LineNumberInputStream & FileInputStream initially null LineNumberInputStream geekline = null; FileInputStream geekinput = null; try{ char c; int a b; // New InputStream : 'ABC' is created geekinput = new FileInputStream('ABC.txt'); geekline = new LineNumberInputStream(geekinput); while((a = geekline.read()) != -1) { // So we convert each integer value to char c = (char)a; // Use of available method : return no. of bytes that can be read a = geekline.available(); System.out.println(c + ' Bytes available : ' + a); } } catch(Exception e) { // In case of error e.printStackTrace(); System.out.println('ERROR Occurs '); } finally { // Closing the streams Once the End of Input Stream is reached if(geekinput != null) geekinput.close(); if(geekline != null) geekline.close(); } } }
Nota:
El codi Java següent no s'executarà aquí, ja que no podem accedir a cap fitxer a l'IDE en línia.
Per tant, copieu el programa al vostre sistema i executeu-lo allà.
El ABC.txt El fitxer utilitzat al programa conté:
available
Sortida:
a Bytes available : 4 v Bytes available : 3 a Bytes available : 3 i Bytes available : 2 l Bytes available : 2 a Bytes available : 1 b Bytes available : 1 l Bytes available : 0 e Bytes available : 0
Sintaxi:
public void setLineNumber(int arg) Parameters : arg : line number to assign Return : void Exception: -----
Implementació:
Java// Java program illustrating the working of setLineNumber() method import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // LineNumberInputStream & FileInputStream initially null LineNumberInputStream geekline = null; FileInputStream geekinput = null; try{ char c; int a b = 0; // New InputStream : 'ABC' is created geekinput = new FileInputStream('ABC.txt'); geekline = new LineNumberInputStream(geekinput); while((a = geekline.read()) != -1) { // So we convert each integer value to char c = (char)a; // Use of setLineNumber() : to set the line no. geekline.setLineNumber(100 + b); // getLineNumber() : returning the current line no. a = geekline.getLineNumber(); System.out.println(c + ' Line No. Set : ' + a); b++; } } catch(Exception e) { // In case of error e.printStackTrace(); System.out.println('ERROR Occurs '); } finally { // Closing the streams Once the End of Input Stream is reached if(geekinput != null) geekinput.close(); if(geekline != null) geekline.close(); } } }
Nota:
El codi Java següent no s'executarà aquí, ja que no podem accedir a cap fitxer a l'IDE en línia.
Per tant, copieu el programa al vostre sistema i executeu-lo allà.
El ABC.txt El fitxer utilitzat al programa conté:
LineNumber
Sortida:
L Line No. Set : 100 i Line No. Set : 101 n Line No. Set : 102 e Line No. Set : 103 N Line No. Set : 104 u Line No. Set : 105 m Line No. Set : 106 b Line No. Set : 107 e Line No. Set : 108 r Line No. Set : 109
Sintaxi:
public long skip(long arg) Parameters : arg : no. of bytes of Input Stream data to skip. Return : no. of bytes to be skipped Exception: IOException : in case I/O error occurs
Implementació:
Java// Java program illustrating the working of setLineNumber() method import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // LineNumberInputStream & FileInputStream initially null LineNumberInputStream geekline = null; FileInputStream geekinput = null; try{ char c; int a b = 0; // New InputStream : 'ABC' is created geekinput = new FileInputStream('ABC.txt'); geekline = new LineNumberInputStream(geekinput); while((a = geekline.read()) != -1) { // So we convert each integer value to char c = (char)a; // skip() : to skip and discard 'arg' bytes // Here skip() will skip and discard 3 bytes. geekline.skip(3); System.out.println(c); } } catch(Exception e) { // In case of error e.printStackTrace(); System.out.println('ERROR Occurs '); } finally{ // Closing the streams Once the End of Input Stream is reached if(geekinput != null) geekinput.close(); if(geekline != null) geekline.close(); } } }
Nota:
El codi Java següent no s'executarà aquí, ja que no podem accedir a cap fitxer a l'IDE en línia.
Per tant, copieu el programa al vostre sistema i executeu-lo allà.
El ABC.txt El fitxer utilitzat al programa conté:
Program Explaining Skip() method
Sortida: '
P r E a n k ) t
Sintaxi:
public int read(byte[] buffer int offset int maxlen) Parameters : buffer : buffer whose data to read offset : starting offset of the data maxlen : max. no. of bytes to read Return : total no. of bytes else return -1 if End of Input Stream is identified Exception: IOException : in case I/O error occurs
Implementació:
Java// Java program illustrating the working of read() method import java.io.*; public class NewClass { public static void main(String[] args) throws IOException { // LineNumberInputStream & FileInputStream initially null LineNumberInputStream geekline = null; FileInputStream geekinput = null; try{ char c; int a; // New InputStream : 'ABC' is created geekinput = new FileInputStream('ABC.txt'); geekline = new LineNumberInputStream(geekinput); // read() method returning Bytes of Input Stream as integer // '-1' indicating to read till end Of Input Stream while((a=geekline.read())!=-1) { // Since read() method returns Integer value // So we convert each integer value to char c = (char)a; System.out.print(c); } } catch(Exception e) { // In case of error e.printStackTrace(); System.out.println('ERROR Occurs '); } finally { // Closing the streams Once the End of Input Stream is reached if(geekinput != null) geekinput.close(); if(geekline != null) geekline.close(); } } }
Nota:
El codi Java següent no s'executarà aquí, ja que no podem accedir a cap fitxer a l'IDE en línia.
Per tant, copieu el programa al vostre sistema i executeu-lo allà.
El ABC.txt El fitxer utilitzat al programa conté:
Read() method
el que fa el mètode és offset = r i maxlen = 5... així que ---i.e. 3 desplaçaments i després 5 bytes, és a dir, Llegir (a continuació, desplaçar-lo de nou, doncs --
Sortida:
The number of char read: 5 ---Read(--
Sintaxi:
public void mark(int arg) Parameters : arg : integer specifying the read limit of the input Stream Return : void
Sintaxi:
public void reset() Parameters : ---- Return : void Exception : -> IOException : If I/O error occurs.
Programa Java que explica els mètodes de la classe LineNumberInputStream: reset() i mark()
java localdateJava
// Java program illustrating the working of LineNumberInputStream method // mark() and reset() import java.io.*; public class NewClass { public static void main(String[] args) throws Exception { LineNumberInputStream geekline = null; FileInputStream geek = null; try{ geek = new FileInputStream('GEEKS.txt'); geekline = new LineNumberInputStream(geek); // read() method : reading and printing Characters one by one System.out.println('Char : ' + (char)geekline.read()); System.out.println('Char : ' + (char)geekline.read()); System.out.println('Char : ' + (char)geekline.read()); // mark() : read limiting the 'geek' input stream geekline.mark(0); // skip() : it results in reading of 'e' in G'e'eeks geekline.skip(1); System.out.println('skip() method comes to play'); System.out.println('mark() method comes to play'); System.out.println('Char : ' + (char)geekline.read()); System.out.println('Char : ' + (char)geekline.read()); System.out.println('Char : ' + (char)geekline.read()); boolean check = geekline.markSupported(); if(geekline.markSupported()) { // reset() method : repositioning the stream to marked positions. geekline.reset(); System.out.println('reset() invoked'); System.out.println('Char : ' + (char)geekline.read()); System.out.println('Char : ' + (char)geekline.read()); } else { System.out.println('reset() method not supported.'); } System.out.println('geekline.markSupported() supported reset() : ' + check); } catch(Exception except) { // in case of I/O error except.printStackTrace(); } finally { // releasing the resources back to the GarbageCollector when closes if(geek != null) geek.close(); if(geekline != null) geekline.close(); } } }
Nota:
Aquest codi no s'executarà a l'IDE en línia, ja que no hi ha cap fitxer d'aquest tipus aquí.
Podeu executar aquest codi al vostre sistema per comprovar el funcionament.
ABC.txt fitxer utilitzat en el codi té
HelloGeeks
Sortida:
Char : H Char : e Char : l skip() method comes to play mark() method comes to play Char : o Char : G Char : e reset() method not supported. geekline.markSupported() supported reset() : false