El método ready() de Reader Class en Java se usa para verificar si este Reader está listo para ser leído o no. Devuelve un valor booleano que indica si el lector está listo.
Sintaxis:
public void ready()
Parámetros: este método no acepta ningún parámetro
Valor de retorno: este método devuelve un valor booleano que indica si este lector está listo para ser leído o no. Devuelve verdadero si está listo. De lo contrario, devuelve falso.
Excepción: este método lanza IOException si ocurre algún error durante la entrada-salida.
Los siguientes métodos ilustran el funcionamiento del método ready():
Programa 1:
// Java program to demonstrate
// Reader ready() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
String str = "GeeksForGeeks";
// Create a Reader instance
Reader reader
= new StringReader(str);
// Check if the Reader is
// ready to be read using ready()
System.out.println("Is Reader ready "
+ "to be read: "
+ reader.ready());
// Get the character
// to be read from the stream
int ch;
// Read the first 5 characters
// to this reader using read() method
// This will put the str in the stream
// till it is read by the reader
for (int i = 0; i < 5; i++) {
ch = reader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
}
reader.close();
}
catch (Exception e) {
System.out.println(e);
}
}
}
Producción:
Is Reader ready to be read: true Integer value of character read: 71 Actual character read: G Integer value of character read: 101 Actual character read: e Integer value of character read: 101 Actual character read: e Integer value of character read: 107 Actual character read: k Integer value of character read: 115 Actual character read: s
Programa 2:
// Java program to demonstrate
// Reader ready() method
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
try {
String str = "GeeksForGeeks";
// Create a Reader instance
Reader reader
= new StringReader(str);
reader.close();
// Check if the Reader is
// ready to be read using ready()
System.out.println("Is Reader ready "
+ "to be read: "
+ reader.ready());
// Get the character
// to be read from the stream
int ch;
// Read the first character
// to this reader using read() method
// This will put the str in the stream
// till it is read by the reader
ch = reader.read();
System.out.println("\nInteger value "
+ "of character read: "
+ ch);
System.out.println("Actual "
+ "character read: "
+ (char)ch);
reader.close();
}
catch (Exception e) {
System.out.println(e);
}
}
}
Producción:
java.io.IOException: Stream closed
Referencia: https://docs.oracle.com/javase/9/docs/api/java/io/Reader.html#ready–