Lesson 3	Using PrintWriter
Objective	Familiarize yourself with how to use PrintWriter.

Using Java PrintWriters

There are four constructors in the PrintWriter class.

public PrintWriter(Writer out)

public PrintWriter(Writer out, boolean autoFlush)

public PrintWriter(OutputStream out)

public PrintWriter(OutputStream out,
boolean autoFlush)

The PrintWriter can either send data to an OutputStream or to another writer. If autoFlush is set to true, the PrintWriter is flushed every time the println() method is invoked.

print( ) and println( ) Methods

The main advantages of the PrintWriter class are the

nine-way overloaded print() method and

the 10-way overloaded println() method.

println() method overloads

public void println()

public void println(boolean x)

public void println(char x)

public void println(int x)

public void println(long x)

public void println(float x)

public void println(double x)

public void println(char x[])

public void println(String x)

public void println(Object x)

Any Java object, variable, or literal can be printed by passing it to a print() or println() method.
The println() method follows its argument with a platform-dependent line separator such as \r\n and then flushes the output if autoFlush is enabled. The print() method does not. Otherwise these methods are the same.

checkError( ) method

None of the methods of the PrintWriter class throw IOExceptions. If any exceptions are thrown, they are caught inside the class. You can check to see whether any exceptions have been thrown with checkError().

public boolean checkError()

This method returns true if an error has occurred and false if it hasn't. There's no easy way to determine exactly what the error was, though.

Other PrintWriter methods

The PrintWriter class also contains other PrintWriter methods listed below.

public void flush()

public void close()

public void write(int c)

public void write(char buf[], int offset, int length)

public void write(char buf[])

public void write(String s, int offset, int length)

public void write(String s)

The usual Writer methods like write() and flush(), though it's rare to use them.