Clase Java.io.Writer en Java – Part 1

La clase java.io.Writer es una clase abstracta. Se utiliza para escribir en secuencias de caracteres. 
Declaración : 
 

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

Constructores : 
 

• Escritor protegido(): crea una nueva secuencia de caracteres que se puede sincronizar en el escritor.
• Escritor protegido (objeto obj): crea un nuevo flujo de caracteres que puede sincronizarse en el objeto dado: ‘obj’.

Métodos: 
 

• write(int char) : java.io.Writer.write(int char) escribe un solo carácter en el flujo de caracteres. Los caracteres que se escriben están contenidos en 16 bits inferiores del valor entero ‘char’, el resto de los 16 bits superiores son ignorados por el método. 
  Sintaxis: 

public void write(int char)
Parameters : 
char : int value of the character to be written.
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.

•  
• write(String str) : java.io.Writer.write(String str) escribe una string en el flujo de caracteres. 
  Sintaxis: 
   

public void write(String str)
Parameters : 
str : string to be written to the character stream.
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.

•  
• write(String str, int offset, int maxlen) : java.io.Writer.write(String str, int offset, int maxlen) escribe una parte de la string en el flujo de caracteres. 
  Sintaxis: 
   

public void write(String str, int offset, int maxlen)
Parameters : 
str : string to be written to the character stream.
offset : start position of the String
maxlen : maximum length upto which string has to written
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.
-> IndexOutOfBoundsException : if offset is -ve or offset + maxlen = -ve || > maxlen

•  
• write(char[] carray) : java.io.Writer.write(char[] carray) escribe una array de caracteres en el flujo de caracteres. 
  Sintaxis: 
   

public void write(char[] carray)
Parameters : 
carray : character array to be written to the character stream
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.

•  
• write(char[] carray, int offset, int maxlen) : java.io.Writer.write(char[] carray, int offset, int maxlen) escribe una parte de la array de caracteres en el flujo de caracteres. 
  Sintaxis: 
   

public abstract void write(char[] carray, int offset, int maxlen)
Parameters : 
carray : character to be written to the character stream
offset : start position of the character array
maxlen : maximum no. of the character of the carray has to written
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.

•  
• close() : java.io.Writer.close() cierra el flujo de caracteres, vaciándolo primero. 
  Sintaxis: 
   

public abstract void close()
Parameters : 
-----------
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.

•  
• flush() : java.io.Writer.flush() vacía el flujo de Writer. Vaciar una invocación de flujo vaciará todos los demás búfer de la string. 
  Sintaxis: 
   

public void flush()
Parameters : 
-----
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.

• Programa Java que ilustra el uso de los métodos de la clase Writer: 
   

// Java program illustrating the working of Writer class methods
// write(int char), write(String str), close()
// write(String str, int offset, int maxlen), flush()
// write(char[] carray, int offset, int maxlen), write(char[] carray)
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        char[] carray = {'G', 'E', 'E', 'K', 'S'};
         
        // Initializing Writer
        Writer geek_writer1 = new PrintWriter(System.out);
        Writer geek_writer2 = new PrintWriter(System.out);
        Writer geek_writer3 = new PrintWriter(System.out);
        Writer geek_writer4 = new PrintWriter(System.out);
        Writer geek_writer5 = new PrintWriter(System.out);
 
        // Use of write(int char) : to write a character
        geek_writer1.write(71);
        geek_writer1.write(70);
        geek_writer1.write(71);
 
        // Use of flush() method
        System.out.print("Using write(int char[]) : ");
        geek_writer1.flush();
 
        String str = "Hello Geeks";
        // Use of write(String str) : to write string
        geek_writer2.write(str);
 
        // Value written by write(String str)
        System.out.print("\nUsing write(String str) : ");
        geek_writer2.flush();
 
        // Use of write(String str, int offset, int maxlen)
        //: to write part of string
        geek_writer3.write(str, 2, 4);
        geek_writer3.write(str, 5, 6);
 
        // Value written by write(String str, int offset, int maxlen)
        System.out.print("\nUsing write(str, offset, maxlen) : ");
        geek_writer3.flush();
 
        geek_writer4.write(carray);
        System.out.print("\nUsing write(char[] carray) : ");
        geek_writer4.flush();
 
        // Use of write(char[] carray, int offset, int maxlen):
        // to write part of char array
        geek_writer5.write(carray, 1, 3);
 
        // Value written by write(String str, int offset, int maxlen)
        System.out.print("\nUsing write(carray, offset, maxlen) : ");
        geek_writer5.flush();
 
        // Use of close() method
        geek_writer1.close();
        geek_writer2.close();
        geek_writer3.close();
        geek_writer4.close();
        geek_writer5.close();
                 
    }
}

• Producción : 
   

Using write(int char[]) : GFG
Using write(String str) : Hello Geeks
Using write(str, offset, maxlen) : llo  Geeks
Using write(char[] carray) : GEEKS
Using write(carray, offset, maxlen) : EEK

•  
• append(char Sw) : java.io.Writer.append(char Sw) agrega un solo carácter al Escritor. 
  Sintaxis: 
   

public Writer append(char Sw)
Parameters : 
Sw : character to be append
Return  :
Writer
Exception :
-> IOException : if in case I/O error occurs.

•  
• append(CharSequence char_sq) : java.io.Writer.append(CharSequence char_sq) agrega la secuencia de caracteres especificada al escritor. 
  Sintaxis: 
   

public Writer append(CharSequence char_sq)
Parameters : 
char_sq : Character sequence to append. 
Return  :
Writer, if char sequence is null, then NULL appends to the Writer.
Exception :
-> IOException : if in case I/O error occurs.

•  
• append(CharSequence char_sq, int start, int end) : java.io.Writer.append(CharSequence char_sq, int start, int end) agrega parte específica de una secuencia de caracteres al Escritor. 
  Sintaxis: 
   

public Writer append(CharSequence char_sq, int start, int end)
Parameters : 
char_sq : Character sequence to append.
start : start of character in the Char Sequence
end : end of character in the Char Sequence
Return  :
void
Exception :
-> IOException : if in case I/O error occurs.
-> IndexOutOfBoundsException : if start or end are -ve or start > end or 
                                  end > char_sq.length

• Programa Java que ilustra el uso de los métodos de la clase Writer: 
   

// Java program illustrating the working of Writer class methods
// append(CharSequence char_sq), append(char Sw)
// append(CharSequence char_sq, int start,int end)
// flush()
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // Initializing String Writer
        Writer geek_writer1 = new PrintWriter(System.out);
        Writer geek_writer2 = new PrintWriter(System.out);
        Writer geek_writer3 = new PrintWriter(System.out);
 
        // Use of write(int char) : to write a character
        geek_writer1.append('G');
        geek_writer1.append('G');
        geek_writer1.append('G');
        geek_writer1.append('G');
        geek_writer1.append('G');
 
        // Use of append(char Sw)
        System.out.print("append(char Sw) : ");
        geek_writer1.flush();
 
 
        // Initializing Character Sequence
        CharSequence char_sq1 = "1 Hello 1";
        CharSequence char_sq2 = " : 2 Geeks 2";
 
        // Use of append(CharSequence char_sq)
        geek_writer2.append(char_sq1);
        geek_writer2.append(char_sq2);
 
        System.out.print("\nappend(char_sq) : ");
        geek_writer2.flush();
 
        // Use of append(CharSequence char_sq,int start,int end)
        geek_writer3.append(char_sq1, 0, 3);
        geek_writer3.append(char_sq2, 3, 6);
 
        System.out.print("\nappend(char_sq,start,end) : ");
        geek_writer3.flush();
 
    }
}

• Producción : 
   

Using write(int char) : GFG
append(char Sw) : GGGGG
append(char_sq) : 1 Hello 1 : 2 Geeks 2
append(char_sq,start,end) : 1 H2 G

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