Java.io.PrintWriter class in Java | Set 1

Java PrintWriter class gives Prints formatted representations of objects to a text-output stream. It implements all of the print methods found in PrintStream. It does not contain methods for writing raw bytes, for which a program should use unencoded byte streams. Unlike the PrintStream class, if automatic flushing is enabled it will be done only when one of the println, printf, or format methods is invoked, rather than whenever a newline character happens to be output. 

These methods use the platform's own notion of line separator rather than the newline character. 

Methods in this class never throw I/O exceptions, although some of its constructors may. The client may inquire as to whether any errors have occurred by invoking checkError(). 

Declaration of Java PrintWriter Class

public class PrintWriter extends Writer  

Constructor and Description

• PrintWriter(File file): Creates a new PrintWriter, without automatic line flushing, with the specified file.
• PrintWriter(File file, String csn): Creates a new PrintWriter, without automatic line flushing, with the specified file and charset.
• PrintWriter(OutputStream out): Creates a new PrintWriter, without automatic line flushing, from an existing OutputStream.
• PrintWriter(OutputStream out, boolean autoFlush): Creates a new PrintWriter from an existing OutputStream.
• PrintWriter(String fileName): Creates a new PrintWriter, without automatic line flushing, with the specified file name.
• PrintWriter(String fileName, String csn): Creates a new PrintWriter, without automatic line flushing, with the specified file name and charset.
• PrintWriter(Writer out): Creates a new PrintWriter, without automatic line flushing.
• PrintWriter(Writer out, boolean autoFlush): Creates a new PrintWriter.

Methods of PrinterWriter class in Java

Methods of PrinterWriter Class in Java are mentioned below:

1. PrintWriter append(char c)

Appends the specified character to this writer

Syntax :public PrintWriter append(char c)

Parameters:
c - The 16-bit character to append

Returns:
This writer

2. PrintWriter append(CharSequence csq, int start, int end)

Appends the specified character sequence to this writer.

Syntax :public PrintWriter append(CharSequence csq,
        int start,int end)
        
Parameters:
        csq - The character sequence from which a subsequence will be appended.
        start - The index of the first character in the subsequence
        end - The index of the character following the last character in the subsequence

Returns:This writer

Throws:
        IndexOutOfBoundsException

3. PrintWriter append(CharSequence csq)

Appends a subsequence of the specified character sequence to this writer.

Syntax :public PrintWriter append(CharSequence csq)

Parameters:
        csq - The character sequence to append.

Returns: This writer

4. boolean checkError()

Flushes the stream and checks its error state.

Syntax :public boolean checkError()

Returns: true if and only if this stream 
has encountered an IOException other than InterruptedIOException, 
or the setError method has been invoked

5. protected void clearError()

Clears the internal error state of this stream.

Syntax :protected void clearError()

6. void close()

Closes the stream and releases any system resources associated with it.

Syntax :public void close()

Specified by:close in class Writer

7. void flush()

Flushes the stream.

Syntax :public void flush()

Specified by:flush in interface Flushable

Specified by:flush in class Writer

8. PrintWriter format(Locale l, String format, Object... args)

Writes a formatted string to this writer using the specified format string and arguments.

Syntax :public PrintWriter format(Locale l,
        String format,
        Object... args)

Parameters:
        l - The locale to apply during formatting. If l is null,
 then no localization is applied.
        format - A format string as described in Format string syntax
        args - Arguments referenced by the format specifiers in the format string. 
The number of arguments is variable and may be zero.

Returns: This writer

Throws:
        IllegalFormatException
        NullPointerException

9. PrintWriter format(String format, Object... args)

Writes a formatted string to this writer using the specified format string and arguments.

Syntax :public PrintWriter format(String format,
        Object... args)

Parameters:
        format - A format string as described in Format string syntax
        args - Arguments referenced by the format specifiers in the format string. 
The number of arguments is variable and may be zero.

Returns: This writer

Throws:
        IllegalFormatException
        NullPointerException 

10. void print(boolean b)

Prints a boolean value.

Syntax :public void print(boolean b)

11. void print(char c)

Prints a character.

Syntax :public void print(char c)

12. void print(char[] s)

Prints an array of characters.

Syntax :public void print(char[] s)

13. void print(double d)

Prints a double-precision floating-point number.

Syntax :public void print(double b)

14. void print(float f)

Prints a floating-point number.

Syntax :public void print(float f)

15. void print(int i)

Prints an integer.

Syntax :public void print(int i)

16. void print(long l)

Prints a long integer.

Syntax :public void print(long l)

17. void print(Object obj)

Prints an object.

Syntax :public void print(Object obj)

18. void print(String s)

Prints a string.

Syntax :public void print(String s)

Example

// Java program to demonstrate PrintWriter
import java.io.*;
import java.util.Locale;

// Driver Class
class PrintWriterDemo {
    // Main Function
    public static void main(String[] args)
    {
        String s = "GeeksforGeeks ";

        // create a new writer
        PrintWriter out = new PrintWriter(System.out);
        char c[] = { 'G', 'E', 'E', 'K' };

        // illustrating print(boolean b) method
        out.print(true);

        // illustrating print(int i) method
        out.print(1);

        // illustrating print(float f) method
        out.print(4.533f);

        // illustrating print(String s) method
        out.print("GeeksforGeeks");
        out.println();

        // illustrating print(Object Obj) method
        out.print(out);
        out.println();

        // illustrating append(CharSequence csq) method
        out.append("Geek");
        out.println();

        // illustrating checkError() method
        out.println(out.checkError());

        // illustrating format() method
        out.format(Locale.UK, "This is my % s program", s);

        // illustrating flush method
        out.flush();

        // illustrating close method
        out.close();
    }
}

Output

        true14.533GeeksforGeeks
        java.io.PrintWriter@1540e19d
        Geek
        false
        This is my GeeksforGeeks program

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