Java - DataOutputStream writeChar(int v) method

Previous
Quiz

Description

The Java DataOutputStream writeChar(int v) method writes a character to the underlying output stream as a two byte value with high byte first. The counter written is incremented by 2 on successful invoking of this method.

Declaration

Following is the declaration for java.io.DataOutputStream.writeChar(int v) method −

 public final void writeChar(int v)

Parameters

v − A char value to be written to the stream.

Return Value

This method does not return any value.

Exception

IOException − If an I/O error occurs.

Example - Usage of DataOutputStream writeChar(int v) method

The following example shows the usage of Java DataOutputStream writeChar(int v) method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte[] buf is initialized with some byte values. A FileOutputStream object is created. Then DataOutputStream is initialized with FileOutputStream object created before.

We've iterated byte array to write each byte as a char to stream using writeChar(). As next step, stream is flushed. As next step, we've created a FileInputStream object based on file written earlier. Then DataInputStream is initialized with FileInputStream object created. Now dataInputStream is iterated to print the contents. Finally we're closing all the streams.

DataOutputStreamDemo.java

 package com.tutorialspoint; import java.io.IOException; import java.io.InputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; public class DataOutputStreamDemo { public static void main(String[] args) throws IOException { InputStream is = null; DataInputStream dis = null; FileOutputStream fos = null; DataOutputStream dos = null; byte[] buf = {65,66,67,68,69,70}; try { // create file output stream fos = new FileOutputStream("test.txt"); // create data output stream dos = new DataOutputStream(fos); // for each byte in the buffer for (byte b:buf) { // write character to the dos dos.writeChar(b); } // force bytes to the underlying stream dos.flush(); // create file input stream is = new FileInputStream("test.txt"); // create new data input stream dis = new DataInputStream(is); // read till end of the stream while(dis.available()>0) { // read character char c = dis.readChar(); // print System.out.print(c); } } catch(Exception e) { // if an 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 −

 ABCDEF

Example - Usage of DataOutputStream writeChar(int v) method

The following example shows the usage of Java DataOutputStream writeChar(int v) method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte[] buf is initialized with some byte values. A FileOutputStream object is created. Then DataOutputStream is initialized with FileOutputStream object created before. As a special case, we're closing the stream and then writing values to check if stream is allowing to write after closing it.

We've iterated byte array to write each byte as a char to stream using writeChar(). As next step, stream is flushed. As next step, we've created a FileInputStream object based on file written earlier. Then DataInputStream is initialized with FileInputStream object created. Now dataInputStream is iterated to print the contents. Finally we're closing all the streams.

DataOutputStreamDemo.java

 package com.tutorialspoint; import java.io.IOException; import java.io.InputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; public class DataOutputStreamDemo { public static void main(String[] args) throws IOException { InputStream is = null; DataInputStream dis = null; FileOutputStream fos = null; DataOutputStream dos = null; byte[] buf = {65,66,67,68,69,70}; try { // create file output stream fos = new FileOutputStream("test.txt"); // create data output stream dos = new DataOutputStream(fos); // close the stream dos.close(); // for each byte in the buffer for (byte b:buf) { // write character to the dos dos.writeChar(b); } // force bytes to the underlying stream dos.flush(); // create file input stream is = new FileInputStream("test.txt"); // create new data input stream dis = new DataInputStream(is); // read till end of the stream while(dis.available()>0) { // read character char c = dis.readChar(); // print System.out.print(c); } } catch(Exception e) { // if an 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.FileOutputStream.writeBytes(Native Method)	at java.base/java.io.FileOutputStream.write(FileOutputStream.java:367)	at java.base/java.io.DataOutputStream.writeChar(DataOutputStream.java:191)	at com.tutorialspoint.DataOutputStreamDemo.main(DataOutputStreamDemo.java:31) Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.io.InputStream.close()" because "is" is null	at com.tutorialspoint.DataOutputStreamDemo.main(DataOutputStreamDemo.java:61)

Example - Writing and Reading a Character Using writeChar(int v)

The following example shows the usage of Java DataOutputStream writeChar(int v) method.

DataOutputStreamDemo.java

 package com.tutorialspoint; import java.io.DataOutputStream; import java.io.DataInputStream; import java.io.FileOutputStream; import java.io.FileInputStream; import java.io.IOException; public class DataOutputStreamDemo { public static void main(String[] args) { try { // Create a DataOutputStream to write to a file FileOutputStream fileOutput = new FileOutputStream("output.dat"); DataOutputStream dataOutput = new DataOutputStream(fileOutput); // Write characters to the file dataOutput.writeChar('A'); // Unicode U+0041 (stored as 2 bytes) dataOutput.writeChar('B'); // Unicode U+0042 (stored as 2 bytes) dataOutput.writeChar('C'); // Unicode U+0043 (stored as 2 bytes) // Close the output stream dataOutput.close(); System.out.println("Characters successfully written to output.dat"); // Read the characters back FileInputStream fileInput = new FileInputStream("output.dat"); DataInputStream dataInput = new DataInputStream(fileInput); // Read and print the characters System.out.println("First character: " + dataInput.readChar()); // A System.out.println("Second character: " + dataInput.readChar()); // B System.out.println("Third character: " + dataInput.readChar()); // C // Close the input stream dataInput.close(); } catch (IOException e) { e.printStackTrace(); } } }

Output

Let us compile and run the above program, this will produce the following result −

 Characters successfully written to output.dat First character: A Second character: B Third character: C

Explanation

Writing Characters

  • writeChar('A') − Writes two bytes (0x00 41 in UTF-16).

  • writeChar('B') − Writes two bytes (0x00 42 in UTF-16).

  • writeChar('C') − Writes two bytes (0x00 43 in UTF-16).

Reading Characters

  • readChar() correctly retrieves and reconstructs the characters from their two-byte Unicode representation.

java_io_dataoutputstream.htm
Print Page
Previous
Next
Advertisements