Java Reader read(CharBuffer)用法及代碼示例

Java中Reader類的read(CharBuffer)方法用於將指定的字符讀取到CharBuffer實例中。此方法將流阻塞到：

它已從流中獲取了一些輸入。
發生了一些IOException
閱讀時已到達流的末尾。

用法:

public int read(CharBuffer charBuffer)

參數：此方法接受強製參數charBuffer，該參數是要在Stream中寫入的CharBuffer實例。

返回值：此方法返回一個整數值，該整數值是從流中讀取的字符數。如果未讀取任何字符，則返回-1。

異常：此方法引發以下異常：

IOException：輸入輸出時發生錯誤。
NullPointerException ：如果要填充的CharBuffer實例為null
ReadOnlyBufferException：如果要填充的CharBuffer實例是隻讀緩衝區

下麵的方法說明了read(CharBuffer)方法的用法方式：

示例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); 
        } 
    } 
}

輸出：

Geeks

示例2:

// 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); 
        } 
    } 
}

輸出：

GeeksForGeeks

參考： https://docs.oracle.com/javase/9/docs/api/java/io/Reader.html#read-java.nio.CharBuffer-

相關用法

注：本文由純淨天空篩選整理自Code_r大神的英文原創作品 Reader read(CharBuffer) method in Java with Examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。