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- Java.io - DataInputStream
- Java.io - DataOutputStream
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- Java.io - FileInputStream
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- Java.io - FilterInputStream
- Java.io - FilterOutputStream
- Java.io - FilterReader
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- Java.io - InputStream
- Java.io - InputStreamReader
- Java.io - LineNumberInputStream
- Java.io - LineNumberReader
- Java.io - ObjectInputStream
- Java.io - ObjectInputStream.GetField
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- io - ObjectOutputStream.PutField
- Java.io - ObjectStreamClass
- Java.io - ObjectStreamField
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- Java.io - Writer
- Java.io package extras
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- Java.io package Useful Resources
- Java.io - Discussion
Java - DataInputStream readUnsignedByte() method
Description
The Java DataInputStream readUnsignedByte() method returns result which is in the range of 0-255.
Declaration
Following is the declaration for java.io.DataInputStream.readUnsignedByte() method −
public final int readUnsignedByte()
Parameters
NA
Return Value
This method returns unsigned 8 bit value.
Exception
IOException − If the stream is closed or the or any I/O error occurs.
EOFException − If the input stream has reached the ends.
Example 1
The following example shows the usage of Java DataInputStream readUnsignedByte() method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte[] buf is initialized with some byte values. A FileOutputStream object is created with a File. Then DataOutputStream is initialized with FileOutputStream object created before. Then byte array is iterated to write byte values to the dataoutputstream.
Once byte arrays is fully written into the stream, we've flush the stream to store the values in the file. Now using FileInputStream and DataInputStream, we're reading the file written earlier. Now we're checking if DataInputStream object has data using available() method. Then using readUnsignedByte() method, we're reading every value as int. Finally we're closing all the streams.
import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; public class DataInputStreamDemo { public static void main(String[] args) throws IOException { InputStream is = null; DataInputStream dis = null; FileOutputStream fos = null; DataOutputStream dos = null; byte[] b = {-124,126}; try { // create file output stream fos = new FileOutputStream("F:\\test.txt"); // create data output stream dos = new DataOutputStream(fos); // for each byte in the buffer for (byte j:b) { // write byte to the data output stream dos.writeByte(j); } // force bytes to the underlying stream dos.flush(); // create file input stream is = new FileInputStream("F:\\test.txt"); // create new data input stream dis = new DataInputStream(is); // read till end of the stream while(dis.available()>0) { // read 8 bit unsigned number int c = dis.readUnsignedByte(); // print System.out.print(c + " "); } } catch(Exception e) { // if any I/O error occurs e.printStackTrace(); } finally { // releases all system resources from the streams if(is!=null) is.close(); if(dos!=null) is.close(); if(dis!=null) dis.close(); if(fos!=null) fos.close(); } } }
Output
Let us compile and run the above program, this will produce the following result −
132 126
Example 2
The following example shows the usage of Java DataInputStream readUnsignedByte() method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte[] buf is initialized with some byte values. A FileOutputStream object is created with a File. Then DataOutputStream is initialized with FileOutputStream object created before. Then byte array is iterated to write byte values to the dataoutputstream.
Once byte arrays is fully written into the stream, we've flush the stream to store the values in the file. Now using FileInputStream and DataInputStream, we're reading the file written earlier. Now we're checking if DataInputStream object has data using available() method. Then using readUnsignedByte() method, we're reading every value as int. Now as a special case, we're closing the stream before reading the values to see if this methods throw exception or not. As a result, we can see the available() method throws the exception.
import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; public class DataInputStreamDemo { public static void main(String[] args) throws IOException { InputStream is = null; DataInputStream dis = null; FileOutputStream fos = null; DataOutputStream dos = null; byte[] b = {-124,126}; try { // create file output stream fos = new FileOutputStream("F:\\test.txt"); // create data output stream dos = new DataOutputStream(fos); // for each byte in the buffer for (byte j:b) { // write byte to the data output stream dos.writeByte(j); } // force bytes to the underlying stream dos.flush(); // create file input stream is = new FileInputStream("F:\\test.txt"); // create new data input stream dis = new DataInputStream(is); // close the streams is.close(); dis.close(); // read till end of the stream while(dis.available()>0) { // read 8 bit unsigned number int c = dis.readUnsignedByte(); // print System.out.print(c + " "); } } catch(Exception e) { // if any I/O error occurs e.printStackTrace(); } finally { // releases all system resources from the streams if(is!=null) is.close(); if(dos!=null) is.close(); if(dis!=null) dis.close(); if(fos!=null) fos.close(); } } }
Output
Let us compile and run the above program, this will produce the following result −
java.io.IOException: Stream Closed at java.base/java.io.FileInputStream.available0(Native Method) at java.base/java.io.FileInputStream.available(FileInputStream.java:330) at java.base/java.io.FilterInputStream.available(FilterInputStream.java:167) at DataInputStreamDemo.main(DataInputStreamDemo.java:44)
Example 3
The following example shows the usage of Java DataInputStream readUnsignedByte() method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte[] buf is initialized with some byte values. A FileOutputStream object is created with a File. Then DataOutputStream is initialized with FileOutputStream object created before. Then byte array is iterated to write byte values to the dataoutputstream.
Once byte arrays is fully written into the stream, we've flush the stream to store the values in the file. Now using FileInputStream and DataInputStream, we're reading the file written earlier. Now we're checking if DataInputStream object has data using available() method. Then using readUnsignedByte() method, we're reading every value as int. Now as a special case, we're reading bytes after all bytes are read using readUnsignedByte() method. As a result, we can see the readUnsignedByte() throws an EOFException.
import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; public class DataInputStreamDemo { public static void main(String[] args) throws IOException { InputStream is = null; DataInputStream dis = null; FileOutputStream fos = null; DataOutputStream dos = null; byte[] b = {-124,126}; try { // create file output stream fos = new FileOutputStream("F:\\test.txt"); // create data output stream dos = new DataOutputStream(fos); // for each byte in the buffer for (byte j:b) { // write byte to the data output stream dos.writeByte(j); } // force bytes to the underlying stream dos.flush(); // create file input stream is = new FileInputStream("F:\\test.txt"); // create new data input stream dis = new DataInputStream(is); // read till end of the stream while(dis.available()>0) { // read 8 bit unsigned number int c = dis.readUnsignedByte(); // print System.out.print(c + " "); } System.out.print(dis.readUnsignedByte()); } catch(Exception e) { // if any I/O error occurs e.printStackTrace(); } finally { // releases all system resources from the streams if(is!=null) is.close(); if(dos!=null) is.close(); if(dis!=null) dis.close(); if(fos!=null) fos.close(); } } }
Output
Let us compile and run the above program, this will produce the following result −
132 126 java.io.EOFException at java.base/java.io.DataInputStream.readUnsignedByte(DataInputStream.java:320) at DataInputStreamDemo.main(DataInputStreamDemo.java:48)
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