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005  public final class Std
006  {
007      static{ new JDK_11_unloading_bug_fix(Std.class); }
008  
009      private static BufferedReader input;        //= null
010      private static PrintWriter    output;       //= null
011      private static PrintWriter    error;        //= null
012      private static PrintWriter    bit_bucket;   //= null
013  


/*****************************************

A private constructor, prevents anyone from manufacturing an instance.

*/


014      private Std(){}
015  


/*****************************************

Get a BufferedReader that wraps System.in

*/


016      public static BufferedReader in()
017      {   if( input == null )
018              synchronized( Std.class )
019              {   if( input == null )
020                      try
021                      {   input = new BufferedReader(
022                                          new InputStreamReader(System.in));
023                      }
024                      catch( Exception e )
025                      {   throw new Error( e.getMessage() );
026                      }
027              }
028          return input;
029      }
030  


/*****************************************

Get a PrintWriter that wraps System.out.

*/


031
032      public static PrintWriter out()
033      {   if( output == null )
034              synchronized( Std.class )
035              {   if( output == null )
036                      output = new PrintWriter( System.out, true );
037              }
038          return output;
039      }
040  


/*****************************************

Get a PrintWriter that wraps System.err.

*/


041      public static PrintWriter err()
042      {   if( error == null )
043              synchronized( Std.class )
044              {   if( error == null )
045                      error = new PrintWriter( System.err, true );
046              }
047          return error;
048      }


/*****************************************

Get an output stream that just discards the characters that are sent to it. This convenience class makes it easy to write methods that are passed a "Writer" to which error messages or status information is logged. You could log output to standard output like this:


    x.method( Std.out() );  // pass in the stream to which messages are logged


You could also cause the logged messages to simply disappear by calling:


    x.method( Std.bit_bucket() );   // discard normal logging messages


*/


049      public static PrintWriter bit_bucket()
050      {   if( bit_bucket == null )
051              synchronized( Std.class )
052              {   if( bit_bucket == null )
053                      bit_bucket = new Bit_bucket();
054              }
055          return bit_bucket;
056      }
058  


/*****************************************

The Bit_bucket class overrides all methods of PrintWriter to do nothing.

/


058  private static final class Bit_bucket extends PrintWriter
059      {
060  private Bit_bucket()
061          {   super( System.err ); // Never used, but must pass something legal.
062          }
063  
064  public void close() {}
065  public void    flush() {}
066  public void  print(boolean b) {}
067  public void    print(char c) {}
068  public void    print(char[] s) {}
069  public void    print(double d) {}
070  public void    print(float f) {}
071  public void    print(int i) {}
072  public void    print(long l) {}
073  public void    print(Object o) {}
074  public void    print(String  s) {}
075  public void    println() {}
076  public void    println(boolean b) {}
077  public void    println(char c) {}
078  public void    println(char[] s) {}
079  public void    println(double d) {}
080  public void    println(float f) {}
081  public void    println(int i) {}
082  public void    println(long l) {}
083  public void    println(Object o) {}
084  public void    write(char[] buf) {}
085  public void    write(char[] buf, int off, int len)  {}
086  public void    write(int c) {}
087  public void    write(String buf) {}
088  public void    write(String buf, int off, int len)  {}
089      }
090


/****************************************

A small test class, reads a line from standard input and echoes it to standard output and standard error. Run it with:

java com.holub.tools.Std\$Test

(Don't type in the \ when using a Microsoft-style shell.)

/


091      static public class Test
092      {
093          static public void main( String[] args ) throws IOException
094          {   String s;
095              while( (s = Std.in().readLine()) != null )
096              {   Std.out().println( s );
097                  Std.err().println( s );
098                  Std.bit_bucket().println( s );
099              }
100          }
101      }
102  }