Java 中 Reader ready()方法,带示例

原文:https://www . geesforgeks . org/reader-reader-ready-in-method-in-Java-with-examples/

Java 中 Reader 类的 ready() 方法用来检查这个 Reader 是否准备好被读取。它返回一个布尔值,表示读取器是否准备好了。

语法:

public void ready()

参数:该方法不接受任何参数

返回值:这个方法返回一个布尔值,它告诉这个阅读器是否准备好被读取。如果它准备好了,它就会变成真的。否则返回假。

异常:如果输入输出时出现错误,该方法抛出异常

下面的方法说明了 ready()方法的工作原理:

程序 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);
        }
    }
}

输出:

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

程序二:

// 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);
        }
    }
}

输出:

java.io.IOException: Stream closed

参考:https://docs . Oracle . com/javase/9/docs/API/Java/io/reader . html # ready–