1. WIKI教程
2. Java.io包
3. int available()

int available()

描述 (Description)

java.io.BufferedInputStream.available()方法返回从输入流中读取的剩余字节数，而不会被下一次调用此输入流的方法阻塞。

声明 (Declaration)

以下是java.io.BufferedInputStream.available()方法的声明。

public int available()

返回值 (Return Value)

此方法返回从此输入流中读取的剩余number of bytes而不会阻塞。

异常 (Exception)

IOException - 如果发生I/O错误。

例子 (Example)

以下示例显示了java.io.BufferedInputStream.available（）方法的用法。

package com.iowiki;
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
public class BufferedInputStreamDemo {
   public static void main(String[] args) throws Exception {
      BufferedInputStream bis = null;
      try {
         // open input stream test.txt for reading purpose.
         inStream = new FileInputStream("c:/test.txt");
         // input stream is converted to buffered input stream
         bis = new BufferedInputStream(inStream);      
         // read until a single byte is available
         while( bis.available() > 0 ) {
            // get the number of bytes available
            Integer nBytes = bis.available();
            System.out.println("Available bytes = " + nBytes );
            // read next available character
            char ch =  (char)bis.read();
            // print the read character.
            System.out.println("The character read = " + ch );
         }
      } catch(Exception e) {
         e.printStackTrace();
      } finally {
         // releases any system resources associated with the stream
         if(inStream!=null)
            inStream.close();
         if(bis!=null)
            bis.close();
      }
   }
}

假设我们有一个文本文件c:/test.txt ，它具有以下内容。 该文件将用作示例程序的输入 -

ABCDE 

让我们编译并运行上面的程序，这将产生以下结果 -

Available bytes = 5
The character read = A
Available bytes = 4
The character read = B
Available bytes = 3
The character read = C
Available bytes = 2
The character read = D
Available bytes = 1
The character read = E