FileInputStream類的available()方法 (FileInputStream Class available() method)
available() method is available in java.io package.
available()方法在java.io包中可用。
available() method is used to return the number of bytes left that can be read from this FileInputStream and without blocking by the next invocation of this method for this FileInputStream.
available()方法用于返回可以從此FileInputStream讀取的剩余字節數，并且不會被此FileInputStream的下一次調用阻塞。
available() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
available()方法是一種非靜態方法，只能通過類對象訪問，如果嘗試使用類名稱訪問該方法，則會收到錯誤消息。
available() method may throw an exception at the time of returning available bytes.
available()方法在返回可用字節時可能會引發異常。
IOException: This exception may throw while getting any input/output error or when this stream is closed by the close() method.
IOException ：在獲取任何輸入/輸出錯誤時或通過close()方法關閉此流時，可能引發此異常。
Syntax:
句法：
public int available();
Parameter(s):
參數：
It does not accept any parameter.
它不接受任何參數。
Return value:
返回值：
The return type of the method is int, it returns the number of available bytes left that can be read from this FileInputStream during unblock.
方法的返回類型為int ，它返回在解除阻塞期間可以從此FileInputStream讀取的剩余可用字節數。
Example:
例：
// Java program to demonstrate the example
// of int available() method
// of FileInputStream
import java.io.*;
public class AvailableOfFIS {
public static void main(String[] args) throws Exception {
FileInputStream fis_stm = null;
int count = 0;
try {
// Instantiates FileInputStream
fis_stm = new FileInputStream("D:\\includehelp.txt");
// Loop to read until available
// bytes left
while ((count = fis_stm.read()) != -1) {
// By using available() method is to
// return the available bytes to be read
int avail_bytes = fis_stm.available();
// Display corresponding bytes value
byte b = (byte) count;
// Display value of avail_bytes and b
System.out.print("fis_stm.available(): " + avail_bytes);
System.out.println(" : " + "byte: " + b);
}
} catch (Exception ex) {
System.out.println(ex.toString());
} finally {
// with the help of this block is to
// free all necessary resources linked
// with the stream
if (fis_stm != null) {
fis_stm.close();
}
}
}
}
Output
輸出量
fis_stm.available(): 15 : byte: 0
fis_stm.available(): 14 : byte: 4
fis_stm.available(): 13 : byte: 74
fis_stm.available(): 12 : byte: 97
fis_stm.available(): 11 : byte: 118
fis_stm.available(): 10 : byte: 97
fis_stm.available(): 9 : byte: 0
fis_stm.available(): 8 : byte: 8
fis_stm.available(): 7 : byte: 87
fis_stm.available(): 6 : byte: 111
fis_stm.available(): 5 : byte: 114
fis_stm.available(): 4 : byte: 108
fis_stm.available(): 3 : byte: 100
fis_stm.available(): 2 : byte: 33
fis_stm.available(): 1 : byte: 33
fis_stm.available(): 0 : byte: 33
翻譯自: https://www.includehelp.com/java/fileinputstream-available-method-with-example.aspx
