DataInputStream类readUnsignedByte()方法 (DataInputStream Class readUnsignedByte() method)

• readUnsignedByte() method is available in java.io package.

  readUnsignedByte()方法在java.io包中可用。

• readUnsignedByte() method is used to read 1 byte (i.e. 8 bit) of data input and returns an unsigned byte value read.

  readUnsignedByte()方法用于读取1个字节(即8位)的数据输入，并返回读取的无符号字节值。

• readUnsignedByte() 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.

  readUnsignedByte()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• readUnsignedByte() method may throw an exception at the time of reading byte.

  readUnsignedByte()方法在读取字节时可能会引发异常。

  • IOException: This exception may throw when this stream is not opened.IOException ：如果未打开此流，则可能引发此异常。
  • EndOfFileException: This exception may throw when this stream has reached its endpoint.EndOfFileException ：当此流到达其端点时，可能引发此异常。

Syntax:

句法：

    public final int readUnsignedByte();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

Return value:

返回值：

The return type of the method is int, it returns 1 byte of data input, manipulated as an unsigned byte value.

方法的返回类型为int ，它返回1个字节的数据输入，并作为无符号字节值进行操作。

Example:

例：

// Java program to demonstrate the example 
// of int readUnsignedByte() method of 
// DataInputStream
import java.io.*;
public class ReadUnsignedByteOfDIS {
public static void main(String[] args) throws IOException {
InputStream is_stm = null;
DataInputStream dis_stm = null;
FileOutputStream fos_stm = null;
DataOutputStream dos_stm = null;
byte[] b_arr = {
125,
111,
-121,
-112
};
try {
// Instantiate FileInputStream, 
// DataInputStream, FileOutputStream
// and DataOutputStream 
fos_stm = new FileOutputStream("C:\\Users\\Preeti Jain\\Desktop\\programs\\includehelp.txt");
dos_stm = new DataOutputStream(fos_stm);
// Loop to write each byte till end
for (byte val: b_arr) {
// By using writeByte() method isto
// write a byte value to the
// DataOutputStream dos_stm
dos_stm.writeByte(val);
}
is_stm = new FileInputStream("C:\\Users\\Preeti Jain\\Desktop\\programs\\includehelp.txt");
dis_stm = new DataInputStream(is_stm);
// Loop To Read Available Data till end
while (dis_stm.available() > 0) {
// By using readUnsignedByte() method isto read 
// unsigned byte at a time from dis_stm
int in = dis_stm.readUnsignedByte();
System.out.println("dis_stm.readUnsignedByte(): " + in );
}
} catch (Exception ex) {
System.out.println(ex.toString());
} finally {
// To free system resources linked
// with these streams
if (is_stm != null)
is_stm.close();
if (dis_stm != null)
dis_stm.close();
if (dos_stm != null)
dos_stm.close();
if (fos_stm != null)
fos_stm.close();
}
}
}

Output

输出量

dis_stm.readUnsignedByte(): 125
dis_stm.readUnsignedByte(): 111
dis_stm.readUnsignedByte(): 135
dis_stm.readUnsignedByte(): 144

翻译自: https://www.includehelp.com/java/datainputstream-readunsignedbyte-method-with-example.aspx