In this tutorial we will learn about the the PrintWriter class in Java.

Java IO PrintWriter

In this tutorial we will learn about the the PrintWriter class in Java.

java.io.PrintWriter class is used for format printing of objects. To print these objects to the text output stream all the print method of PrintStream class is implemented by this class. This class extends Writer class and writes the character data. However, to write on the console in Java System.out is provided, except that the PrintWriter is also provided to write on console. PrintWriter is a character based class which makes the Java program easy for Internationalization. Objects of this class can be created by using various of its Constructors.

Constructor Details

Constructor	Description
PrintWriter(File file)	This constructor is used to create a new PrintWriter object with the given file name. Using this constructor output can be written to the file. This method doesn't flushes line automatically. Syntax : public PrintWriter(File file) throws FileNotFoundException
PrintWriter(File file, String csn)	This constructor is used to create a new PrintWriter object with the given file name and charset. Using this constructor output can be written to the file with the specified charset. This method doesn't flushes line automatically. Syntax : public PrintWriter(File file, String csn) throws FileNotFoundException, UnsupportedEncodingException
PrintWriter(OutputStream out)	This constructor is used to create a new PrintWriter object with the OutputStream already existed. This constructor doesn't flushes line automatically. Syntax : public PrintWriter(OutputStream out)
PrintWriter(OutputStream out, boolean autoFlush)	This method is used to create a new PrintWriter object with the OutputStream already existed and a boolean value for auto flushing. Automatic flushing of line based on the boolean value. Syntax : public PrintWriter(OutputStream out, boolean autoFlush)
PrintWriter(String fileName)	This constructor creates a new PrintWriter object with the given file name. Using this constructor output can be written to the file. This method doesn't flushes line automatically. Syntax : public PrintWriter(String fileName) throws FileNotFoundException
PrintWriter(String fileName, String csn)	This constructor creates a new PrintWriter object with the given file name and specified charset. This method doesn't flushes the line automatically. Syntax : public PrintWriter(String fileName, String csn) throws FileNotFoundException, UnsupportedEncodingException
PrintWriter(Writer out)	This constructor is used to create a new PrintWriter object with an instance of Writer (character-output stream). This method doesn't flushes the line automatically. Syntax : public PrintWriter(Writer out)
PrintWriter(Writer out, boolean autoFlush)	This constructor creates a new PrintWriter object with an instance of Writer (character-output stream) and a boolean value for auto flushing. Automatic flushing of line based on the boolean value. Syntax : public PrintWriter(Writer out, boolean autoFlush)

Methods Detail

• append(char c) : This method is used to write the characters with the existing characters into the writer.
  
  Syntax : public PrintWriter append(char c)
   
• append(CharSequence csq) : This method is used to write the sequence of characters with the existing characters into the writer.
  
  Syntax : append(CharSequence csq)
   
• append(CharSequence csq, int start, int end) : This method is used to write the specified portion of a sequence of characters with the existing characters into the writer.
  
  Syntax : public PrintWriter append(CharSequence csq, int start, int end)
   
• checkError() : This method returns a boolean value which specifies the state of an error (whether the print stream has encountered error or not) and if the stream is not closed then this method flushes the stream.
  
  Syntax : public boolean checkError()
   
• clearError() : This method is used to clear the state of error.
  
  Syntax : protected void clearError()
   
• close() : This method is used to close the stream as well as to release the resources associated with the stream.
  
  Syntax : public void close()
   
• flush() : This method is used to flush the stream.
  
  Syntax : public void flush()
   
• format(Locale l, String format, Object... args) : This method is used to write a string, formatted by the given Locale, format string and arguments, to the writer.
  
  Syntax : public PrintWriter format(Locale l,String format, Object... args)
   
• format(String format, Object... args) : This method is used to write a string, formatted by the given format string and arguments, to the writer.
  
  Syntax : public PrintWriter format(String format, Object... args)
   
• print(boolean b) : This method is used to print a boolean value.
  
  Syntax : public void print(boolean b)
   
• print(char c) : This method is used to print a character value.
  
  Syntax : public void print(char c)
   
• print(char[] s) : This method is used to print an array of characters.
  
  Syntax : public void print(char[] s)
   
• print(double d) : This method is used to print a double-precision floating point number value.
  
  Syntax : public void print(double d)
   
• print(float f) : This method is used to print a float value.
  
  Syntax : public void print(float f)
   
• print(int i) : This method is used to print an integer value.
  
  Syntax : public void print(int i)
   
• print(long l) : This method is used to print long integer value.
  
  Syntax : public void print(long l)
   
• print(Object obj) : This method is used to print an Object.
  
  Syntax : public void print(Object obj)
   
• print(String s) : This method is used to print a String.
  
  Syntax : public void print(String s)
   
• printf(Locale l, String format, Object... args) : This method is used to write a string, formatted by the given Locale, format string and arguments, to the writer.
  
  Syntax : public PrintWriter printf(Locale l, String format, Object... args)
   
• printf(String format, Object... args) : This method is used to write a string, formatted by the given format string and arguments, to the writer.
  
  Syntax : public PrintWriter printf(String format, Object... args)
   
• println() : This method is used to write a new line into the writer.
  
  Syntax : public void println()
   
• println(boolean x) : Using this method a boolean value is printed first and then the current line is terminated.
  
  Syntax : public void println(boolean x)
   
• println(char x) : Using this method a character is printed first and then the current line is terminated.
  
  Syntax : public void println(char x)
   
• println(char[] x) : Using this method an array of characters is printed first and then the current line is terminated.
  
  Syntax : public void println(char[] x)
   
• println(double x) : Using this method double-precision floating point number value is printed first and then the current line is terminated.
  
  Syntax : public void println(double x)
   
• println(float x) : Using this method floating point number value is printed first and then the current line is terminated.
  
  Syntax : public void println(float x)
   
• println(int x) : Using this method an integer is printed first and then the current line is terminated.
  
  Syntax : public void println(int x)
   
• println(long x) : Using this method long integer value is printed first and then the current line is terminated.
  
  Syntax : public void println(long x)
   
• println(Object x) : Using this method an Object is printed first and then the current line is terminated.
  
  Syntax : public void println(Object x)
   
• println(String x) : Using this method string is printed first and then the current line is terminated.
  
  Syntax : public void println(String x)
   
• setError() : This method shows the occurrence of an error.
  
  Syntax : protected void setError()
   
• write(char[] buf) : This method is used to write caharacter's array.
  
  Syntax : public void write(char[] buf)
   
• write(char[] buf, int off, int len) : This method is used to write specified part of an array of characters started from the offset off.
  
  Syntax : public void write(char[] buf, int off, int len)
   
• write(int c) : This method is used to write a character.
  
  Syntax : public void write(int c)
   
• write(String s) : This method is used to write a string.
  
  Syntax : public void write(String s)
   
• write(String s, int off, int len) : This method is used to write a specified length of string started from the specified offset.
  
  Syntax : public void write(String s, int off, int len)

Example

Here I am giving a simple example which will demonstrate you about how to use the PrintWriter in the Java applications. In this example I have created a PrintWriter object using the constructor PrintWriter(File file) and various of methods to print/write the characters to the file.

Source Code

JavaPrintWriterExample.java

import java.io.PrintWriter;
import java.io.File;
import java.util.Locale;

public class JavaPrintWriterExample {

   public static void main(String[] args) {
      String s = "PrintWriter";
      int i = 50;
      try {         
         
         File file = new File("file.txt");        

         // create a new PrintWriter with the specified file
         PrintWriter pw = new PrintWriter(file);

         // format text with specified locale.
         // %s indicates a string will be placed there, which is s
         pw.format(Locale.US, "This is a %s example", s);

         // usage line.separator
         pw.println();

         // write integer
         pw.println(i);

         // write character
         pw.write(i);

         // usage line.separator
         pw.println();
         
         // format text with specified locale
         // %d indicates a integer will be placed there, which is 100
         pw.format("This is a %s example with %d", s, i);
         
         System.out.println();        
         System.out.println("Data written to the file successfully");

         // flush the writer
         pw.flush();

         PrintWriter pw1 = new PrintWriter(System.out);
         pw1.println();
         pw1.println("Data on console : ");
         pw1.format(Locale.US, "This is a %s example", s);
         pw1.println();
         pw1.println(i);
         pw1.write(i);
         pw1.println();
         pw1.format("This is a %s example with %d", s, i);
         pw1.println();
         pw1.flush();

      }
   catch (Exception ex)
      {
          System.out.println(ex);
      }
   }
}

Output

When you will execute the above example you will get the output as follows :

Source code of this example can also be downloaded from the link given below.

Download Source Code

Related Tags for Java IO PrintWriter:

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