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Java - DataOutputStream writeChars(String value)
Description
The Java DataOuputStream writeChars(String s) method writes a character sequence to the stream.
Declaration
Following is the declaration for java.io.DataOutputStream.writeChars(String s) method −
public final void writeChars(String s)
Parameters
s − a string value to be written to the underlying output stream.
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 writeChars(String value) method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A String is initialized with some text. A FileOutputStream object is created. Then DataOutputStream is initialized with FileOutputStream object created before. We've written the string to stream using writeChars() method. 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; String buf = "Hello World!!"; try { // create file output stream fos = new FileOutputStream("F:\\test.txt"); // create data output stream dos = new DataOutputStream(fos); // write string to the dos dos.writeChars(buf); // 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 −
Hello World!!
Example 2
The following example shows the usage of Java DataOutputStream writeChars(String value) method. We've created InputStream, DataInputStream, FileOutputStream and DataOutputStream reference. A String is initialized with some text. A FileOutputStream object is created. Then DataOutputStream is initialized with FileOutputStream object created before. As a special case, we're closing the stream before writing any value to check if it supports writing values after closing it.
We've written the string to stream using writeChars() method. 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; String buf = "Hello World!!"; try { // create file output stream fos = new FileOutputStream("F:\\test.txt"); // create data output stream dos = new DataOutputStream(fos); // close the stream dos.close(); // write string to the dos dos.writeChars(buf); // 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.writeChars(DataOutputStream.java:297) at DataOutputStreamDemo.main(DataOutputStreamDemo.java:27) Exception in thread "main" java.lang.NullPointerException at DataOutputStreamDemo.main(DataOutputStreamDemo.java:56)
As underlying stream FileOutputStream is not supporting write to stream after closing it, we get exception in program execution.