Java - DataOutputStream writeChar(int value)

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Description

The Java DataOuputStream 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.

Return Value

This method does not return any value.

Exception

IOException − If an I/O error occurs.

Example 1

The following example shows the usage of Java DataOutputStream writeChar(int b) method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte array 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.

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("F:\\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("F:\\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 2

The following example shows the usage of Java DataOutputStream writeChar(int b) method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A byte array 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.

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("F:\\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("F:\\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.write(Native Method)
	at java.base/java.io.FileOutputStream.write(FileOutputStream.java:318)
	at java.base/java.io.DataOutputStream.writeChar(DataOutputStream.java:182)
	at DataOutputStreamDemo.main(DataOutputStreamDemo.java:29)
Exception in thread "main" java.lang.NullPointerException
	at DataOutputStreamDemo.main(DataOutputStreamDemo.java:59)

As underlying stream FileOutputStream is not supporting write to stream after closing it, we get exception in program execution.