El método read() de java.nio.CharBuffer Class se utiliza para leer caracteres en el búfer de caracteres especificado. El búfer se utiliza como depósito de caracteres tal cual: los únicos cambios realizados son los resultados de una operación de colocación. No se realiza ningún volteo o rebobinado del búfer.
Sintaxis:
public int read(CharBuffer target)
Parámetro: este método toma el búfer para leer caracteres.
Valor devuelto: este método devuelve el número de caracteres agregados al búfer, o -1 si esta fuente de caracteres está al final.
Excepción: este método arroja la siguiente excepción: –
- IOException : si se produce un error de E/S
- NullPointerException : si el objetivo es nulo
- ReadOnlyBufferException : si el objetivo es un búfer de solo lectura
A continuación se muestran los ejemplos para ilustrar el método read():
Ejemplos 1:
// Java program to demonstrate
// read() method
import java.nio.*;
import java.util.*;
import java.io.IOException;
public class GFG {
public static void main(String[] args)
{
try {
// Declare and initialize the char array
char[] cb1 = { 'x', 'y', 'z' };
char[] cb2 = { 'a', 'b', 'c', 'd', 'e' };
// wrap the char array into CharBuffer
// using wrap() method
CharBuffer charBuffer1
= CharBuffer.wrap(cb1);
// wrap the char array into CharBuffer
// using wrap() method
CharBuffer charBuffer2
= CharBuffer.wrap(cb2);
// print the byte buffer
System.out.println("CharBuffer Before operation is: "
+ Arrays.toString(
charBuffer1.array())
+ "\nTarget Charbuffer: "
+ Arrays.toString(
charBuffer2.array()));
// Get the value of the number of Character
// read from the charBuffer
// using read() method
int value
= charBuffer1
.read(charBuffer2);
// print the byte buffer
System.out.println("\nCharBuffer After operation is: "
+ Arrays.toString(
charBuffer1.array())
+ "\nTarget Charbuffer: "
+ Arrays.toString(
charBuffer2.array())
+ "\nno of value changed: "
+ value);
}
catch (IOException e) {
System.out.println("an I/O error occurs");
System.out.println("Exception throws: " + e);
}
catch (NullPointerException e) {
System.out.println("target charbuffer is null");
System.out.println("Exception throws: " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("target is a read only buffer");
System.out.println("Exception throws: " + e);
}
}
}
Producción:
CharBuffer Before operation is: [x, y, z] Target Charbuffer: [a, b, c, d, e] CharBuffer After operation is: [x, y, z] Target Charbuffer: [x, y, z, d, e] no of value changed: 3
Ejemplos 2: para NullPointerException
// Java program to demonstrate
// read() method
import java.nio.*;
import java.util.*;
import java.io.IOException;
public class GFG {
public static void main(String[] args)
{
try {
// Declare and initialize the char array
char[] cb1 = { 'x', 'y', 'z' };
// wrap the char array into CharBuffer
// using wrap() method
CharBuffer charBuffer1
= CharBuffer.wrap(cb1);
// print the byte buffer
System.out.println("CharBuffer Before operation is: "
+ Arrays.toString(
charBuffer1.array()));
// Get the value of number of Character
// read from the charBuffer
// using read() method
int value = charBuffer1.read(null);
}
catch (IOException e) {
System.out.println("\nan I/O error occurs");
System.out.println("Exception throws: " + e);
}
catch (NullPointerException e) {
System.out.println("\ntarget charbuffer is null");
System.out.println("Exception throws: " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("\ntarget is a read only buffer");
System.out.println("Exception throws: " + e);
}
}
}
Producción:
CharBuffer Before operation is: [x, y, z] target charbuffer is null Exception throws: java.lang.NullPointerException
Ejemplos 3: Para ReadOnlyBufferException
// Java program to demonstrate
// read() method
import java.nio.*;
import java.util.*;
import java.io.IOException;
public class GFG {
public static void main(String[] args)
{
try {
// Declare and initialize the char array
char[] cb1 = { 'x', 'y', 'z' };
char[] cb2 = { 'a', 'b', 'c', 'd', 'e' };
// wrap the char array into CharBuffer
// using wrap() method
CharBuffer charBuffer1
= CharBuffer.wrap(cb1);
// wrap the char array into CharBuffer
// using wrap() method
CharBuffer charBuffer2
= CharBuffer.wrap(cb2);
// print the byte buffer
System.out.println("CharBuffer Before operation is: "
+ Arrays.toString(
charBuffer1.array())
+ "\nTarget Charbuffer: "
+ Arrays.toString(
charBuffer2.array()));
// converting Charbuffer to readonlybuff
CharBuffer readonlybuff
= charBuffer2.asReadOnlyBuffer();
// Get the value of number of Character
// read from the charBuffer
// using read() method
int value = charBuffer1.read(readonlybuff);
// print the byte buffer
System.out.println("\nCharBuffer After operation is: "
+ Arrays.toString(
charBuffer1.array())
+ "\nTarget Charbuffer: "
+ Arrays.toString(
charBuffer2.array())
+ "\nno of value changed: "
+ value);
}
catch (IOException e) {
System.out.println("\nan I/O error occurs");
System.out.println("Exception throws: " + e);
}
catch (NullPointerException e) {
System.out.println("\ntarget charbuffer is null");
System.out.println("Exception throws: " + e);
}
catch (ReadOnlyBufferException e) {
System.out.println("\ntarget is a read only buffer");
System.out.println("Exception throws: " + e);
}
}
}
Producción:
CharBuffer Before operation is: [x, y, z] Target Charbuffer: [a, b, c, d, e] target is a read only buffer Exception throws: java.nio.ReadOnlyBufferException
Referencia: https://docs.oracle.com/javase/9/docs/api/java/nio/CharBuffer.html#read-java.nio.CharBuffer-
Publicación traducida automáticamente
Artículo escrito por RohitPrasad3 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA