Java PushbackReader read(char, int, int)用法及代碼示例

Java中的PushbackReader類的read(char []，int，int)方法用於將指定長度的字符以指定的偏移量讀取到數組中。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(char[] charArray, 
                     int offset, 
                     int length)

參數：此方法接受三個強製參數：

charArray這是要寫入流中的字符數組。
offset這是要在數組中寫入字符的偏移量索引。
length這是要寫入數組的字符數。

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。
IndexOutOfBoundsException：如果偏移值不在字符數組範圍內

以下方法說明了read(char []，int，int)方法的用法方式：

程序1:

// Java program to demonstrate 
// PushbackReader read(char, int, int) method 
  
import java.io.*; 
import java.util.*; 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        try { 
            // Initializing a StringReader 
            // and PushbackReader 
            String s = "GeeksForGeeks"; 
  
            StringReader stringReader 
                = new StringReader(s); 
            PushbackReader pushbackReader 
                = new PushbackReader(stringReader); 
  
            // Get the character array 
            // to be read from the stream 
            char[] charArray = new char[5]; 
  
            // Get the offset index 
            int offset = 0; 
  
            // Get the length 
            int length = 5; 
  
            // Read the charArray 
            // to this reader using read() method 
            // This will put the str in the stream 
            // till it is read by the reader 
            pushbackReader 
                .read(charArray, offset, length); 
  
            // Print the read charArray 
            System.out.println( 
                Arrays.toString(charArray)); 
  
            // Close the stream 
            pushbackReader.close(); 
            System.out.println("Stream Closed."); 
        } 
        catch (Exception e) { 
            System.out.println(e); 
        } 
    } 
}

輸出：

[G, e, e, k, s]
Stream Closed.

程序2:

// Java program to demonstrate 
// PushbackReader read(char, int, int) method 
  
import java.io.*; 
import java.util.*; 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        try { 
            // Initializing a StringReader 
            // and PushbackReader 
            String s = "GFG"; 
  
            StringReader stringReader 
                = new StringReader(s); 
            PushbackReader pushbackReader 
                = new PushbackReader(stringReader); 
  
            // Get the character array 
            // to be read from the stream 
            char[] charArray = new char[5]; 
  
            // Get the offset index 
            int offset = 0; 
  
            // Get the length 
            int length = 2; 
  
            // Read the charArray 
            // to this reader using read() method 
            // This will put the str in the stream 
            // till it is read by the reader 
            pushbackReader 
                .read(charArray, offset, length); 
  
            // Print the read charArray 
            System.out.println( 
                Arrays.toString(charArray)); 
  
            // Close the stream 
            pushbackReader.close(); 
            System.out.println("Stream Closed."); 
        } 
        catch (Exception e) { 
            System.out.println(e); 
        } 
    } 
}

輸出：

[G, F,,, ]
Stream Closed.

參考： https://docs.oracle.com/javase/9/docs/api/java/io/PushbackReader.html#read-char:A-int-int-

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注：本文由純淨天空篩選整理自srinam大神的英文原創作品 PushbackReader read(char, int, int) 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。