Java Coding Style Guide

Comments

public class Power
{
    /**
    * @param  radix   the base for exponentiation
    * @param  expon   the exponent used
    * @return         the result of radix raised to the expon
    * this can be a reciprocal if the the expon is negative
    **/
    public static int power ( int radix, int expon )
    {
        if ( expon < 0 )
        {
            // the answer would be a float
            // we are going to return the reciprocal instead
            // so we can still return an int
            expon *= -1;
        }
        int rval = 1;
        while ( expon > 0 )
        {
            rval *= radix;
            --expon;
        }
        return rval;
    }
    /* main does not need block comments */
    public static final void main ( String args [] )
    {
        System.out.printf ( "%d ^ %d = %d\n", 2, 3, power(2,3) );
        System.out.printf ( "%d ^ %d = %d\n", 3, 2, power(2,3) );
    }
}

Indenting

import java.io.*;
import java.util.*;

class ReadLine
{
    public static void main ( String[] args )
    {
        // System.in is the keyboard aka stdin
        InputStreamReader isr = new InputStreamReader( System.in );
        // input buffering
        BufferedReader in = new BufferedReader ( isr );
        String curLine = "";
        System.out.println( "input now !!" );
        try
        {
            while ( ( curLine = in.readLine() ) != null )
            {
                //System.out.println( "the line is '" + curLine + "'" );
                // break up the line into its words
                StringTokenizer st =
                    new StringTokenizer ( curLine,
                            " \t\n\f\r,.;:!@" );
                while ( st.hasMoreTokens() )
                {
                    String token = st.nextToken();
                    System.out.println( "the token is '" +
                            token + "'" );
                }
            }
        }
        catch ( IOException dummy_variable )
        {
            System.out.println( "this is very bad" );
        }
    }
}

                StringTokenizer st =
                    new StringTokenizer ( curLine,
                            " \t\n\f\r,.;:!@" );

Curly Braces

Here is an example of west coast which is BAD.

    for( int i = 0; i < 10 ; i ++ ) {
        tmp += arr[i];
    }

    for( int i = 0; i < 10 ; i ++ )
    {
        tmp += arr[i];
    }

Return Points

Here is what I DON'T want to see.

public static bool func( int n )
{
    if ( n > 10 )
    {
        return true;
    }
    else
    {
        return false;
    }
}

public static bool func( int n )
{
    bool rval = false;
    if ( n > 10 )
    {
        rval = true;
    }
    return rval;
}

Format Width

Break and Continue

Files and File Contents

• All classes will have their own source file unless they are nested. And nesting of classes must have a valid reason.
• If a program has multiple source files, the main function will be in a file named 'Main.java', and the program should build when I "compile" it.
• If the main is correct named, here is a "Makefile" that will build your project.

  
  JC=javac
  JFLAGS=-Xlint
  
  .SUFFIXES: .java .class
  .java.class:
          $(JC) $(JFLAGS) $*.java
  
  CLASSES=Main.class
  
  all: $(CLASSES)
  clean:
          -rm -f *.class
  

  After putting that in a file named "Makefile", you can run "make" in the shell, or ":make" in vim and it will build your project. This is hardcoded to build Main.java, but you could change CLASSES to compile any source file(s).

Statements per line

Here is what I DON'T want to see.

foo = y; bar = z;
if ( foo == bar ) x = 5;

foo = y;
bar = z;
if ( foo == bar )
    x = 5;