Java 中的 Reader read(CharBuffer)方法，示例

原文:https://www . geeksforgeeks . org/reader-readcharbuffer-method-in-Java-with-examples/

Java 中 Reader 类的 read(CharBuffer) 方法用于将指定的字符读入 CharBuffer 实例。这个方法阻塞流直到:

  • It takes some input from the stream.
  • Some IOException occurred.
  • It has reached the end of the stream when reading.

语法:

public int read(CharBuffer charBuffer)

参数:这个方法接受一个强制参数 charBuffer ，它是要写入流中的 charBuffer 实例。

返回值:该方法返回一个整数值，即从流中读取的字符数。如果未读取任何字符，则返回-1。

异常:如果输入输出时出现错误，该方法抛出以下异常:

  • Exception: .
  • 空指针异常:你好载入缓冲区是陈列夫吗
  • readonlybufferexception: If the CharBuffer instance to be filled is a read-only buffer

下面的方法说明了 read(CharBuffer)方法的工作原理:

程序 1:

// Java program to demonstrate
// Reader read(CharBuffer) method

import java.io.*;
import java.util.*;
import java.nio.CharBuffer;

class GFG {
    public static void main(String[] args)
    {

        try {

            String str = "GeeksForGeeks";

            // Create a Reader instance
            Reader reader
                = new StringReader(str);

            // Get the CharBuffer instance
            // to be read from the stream
            CharBuffer charBuffer
                = CharBuffer.allocate(5);

            // Read the charBuffer
            // to this reader using read() method
            // This will put the str in the stream
            // till it is read by the reader
            reader.read(charBuffer);

            // Print the read charBuffer
            System.out.println(charBuffer
                                   .flip()
                                   .toString());

            reader.close();
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出:

Geeks

程序二:

// Java program to demonstrate
// Reader read(CharBuffer) method

import java.io.*;
import java.util.*;
import java.nio.CharBuffer;

class GFG {
    public static void main(String[] args)
    {

        try {

            String str = "GeeksForGeeks";

            // Create a Reader instance
            Reader reader
                = new StringReader(str);

            // Get the CharBuffer instance
            // to be read from the stream
            CharBuffer charBuffer
                = CharBuffer
                      .allocate(
                          str.length());

            // Read the charBuffer
            // to this reader using read() method
            // This will put the str in the stream
            // till it is read by the reader
            reader.read(charBuffer);

            // Print the read charBuffer
            System.out.println(charBuffer
                                   .flip()
                                   .toString());

            reader.close();
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

输出:

GeeksForGeeks

参考:https://docs . Oracle . com/javase/9/docs/API/Java/io/reader . html # read-Java . nio . charbuffer-

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