Buferizēta rakstzīmju ievades straume, kas seko rindu numuriem. Šī klase definē metodes setLineNumber(int) un getLineNumber(), lai attiecīgi iestatītu un iegūtu pašreizējo rindas numuru.
Pēc noklusējuma līniju numerācija sākas ar 0. Šis skaitlis palielinās katrā līnijas beigu punktā, kad dati tiek nolasīti, un to var mainīt, izsaucot setLineNumber(int).
Tomēr ņemiet vērā, ka setLineNumber(int) faktiski nemaina pašreizējo pozīciju straumē; tas maina tikai vērtību, ko atgriezīs getLineNumber().
Tiek uzskatīts, ka rindiņa ir beigusies ar jebkuru no rindas padevi ('n'), karieta atgriešanos ('r') vai karietes atgriešanos, kam tūlīt seko rindas padeve.
Konstruktori:
LineNumberReader(Lasītājs iekšā):
Izveidojiet jaunu rindu numerācijas lasītāju, izmantojot noklusējuma ievades bufera izmēru.
LineNumberReader(lasītājs int sz) :
Izveidojiet jaunu rindu numerācijas lasītāju, kas nolasa rakstzīmes norādītā izmēra buferī. Metodes:
int getLineNumber() :
Get the current line number.
Syntax : public int getLineNumber() Returns: The current line number
tukšuma atzīme (int readAheadLimit) :
Mark the present position in the stream.Subsequent calls to reset() will attempt to reposition the stream to this point and will also reset the line number appropriately.
Syntax : public void mark(int readAheadLimit) throws IOException Parameters: readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. After reading this many characters attempting to reset the stream may fail. Throws: IOException
int lasīt() :
Read a single character.Line terminators are compressed into single newline ('n') characters. Whenever a line terminator is read the current line number is incremented.
Syntax : public int read() throws IOException Returns: The character read or -1 if the end of the stream has been reached Throws: IOException
int read(char[] cbuf int off int len) :
Read characters into a portion of an array.Whenever a line terminator is read the current line number is incremented.
Syntax : public int read(char[] cbuf int off int len) throws IOException Parameters: cbuf - Destination buffer off - Offset at which to start storing characters len - Maximum number of characters to read Returns: The number of bytes read or -1 if the end of the stream has already been reached Throws: IOException
String readLine() :
Read a line of text.Whenever a line terminator is read the current line number is incremented.
Syntax : public String readLine() throws IOException Returns: A String containing the contents of the line not including any line termination characters or null if the end of the stream has been reached Throws: IOException
nevar atiestatīt () :
Reset the stream to the most recent mark.
Syntax : public void reset() throws IOException Throws: IOException
spēkā neesošs setLineNumber(int lineNumber) :
Set the current line number.
Syntax : public void setLineNumber(int lineNumber) Parameters: lineNumber - An int specifying the line number
garš izlaidums (garš n):
Skip characters.
Syntax : public long skip(long n) throws IOException Parameters: n - The number of characters to skip Returns: The number of characters actually skipped Throws: IOException IllegalArgumentException
Programma: Java
//Java program demonstrating LineNumberReader methodsimportjava.io.FileReader;importjava.io.IOException;importjava.io.LineNumberReader;classLineNumberReaderDemo{publicstaticvoidmain(String[]args)throwsIOException{FileReaderfr=newFileReader('file.txt');LineNumberReaderlnr=newLineNumberReader(fr);charc[]=newchar[20];//illustrating setLineNumber()lnr.setLineNumber(0);//illustrating setSystem.out.println(lnr.getLineNumber());//illustrating markSupported() methodif(lnr.markSupported()){System.out.println('mark() method is supported');//illustrating mark methodlnr.mark(100);}/*File Contents * This is first line this is second line This is third line *///skipping 19 characterslnr.skip(19);//illustrating ready() methodif(lnr.ready()){//illustrating readLine() methodSystem.out.println(lnr.readLine());//illustrating read(char c[]int offint len)lnr.read(c);for(inti=0;i<20;i++){System.out.print(c[i]);}//illustrating reset() methodlnr.reset();for(inti=0;i<18;i++){//illustrating read() methodSystem.out.print((char)lnr.read());}intch;//illustrating read() methodSystem.out.println(lnr.readLine());while((ch=lnr.read())==1)System.out.print((char)ch);}//close the streamlnr.close();}}
Izvade:
0 mark() method is supported this is second line This is third line This is first line