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One of Java's great appeals is that the language provides out-of-the-box GUI development capabilities. Still, a lot of us use Java to write command line tools. Such tools are great to automate batch and offline processes. This article presents a framework that jump-starts the development of such tools.

Command line tools are usually invoked from a shell (e.g., DOS prompt, sh, ksh, etc.) and perform a certain task. The task can be customized based on the command line arguments. For instance:

telnet foo.bar.com

attempts to open a telnet connection to host foo.bar.com. It uses the default telnet port. The next example:

telnet -p 3434 foo.bar.com

attempts a similar connection using port 3434.

Command line tools can be as simple or as complicated as the developer desires. An example of a simple command line tool is the echo command found in most shells. On the other hand, the Java compiler and the Java Virtual Machine (JVM) are complex command line tools.

Java presents the command line arguments in an array of strings. This is already a huge improvement over C and C++, in which the arguments are presented as an array of C strings, i.e., an array of pointers to arrays of characters. Yet it comes short of the developer's desire to get the arguments parsed and ready to use.

Since I published my 1997 C++ command line parsing framework (see Reference), many readers have e-mailed me with requests and suggestions. The top two requests have been for a Java implementation and an improvement to handle arrays of arguments. In this article I present a total rewrite of the framework with improvements for Java programmers.

Using the Framework
Before moving to the implementation I'll demonstrate how to use the framework to write a command line utility. Let's say you want to write a utility called "mycat" - like the UNIX cat - which takes a number of files and concatenates them together into a larger file. A -v option turns verbose output on and off. A -l option allows the insertion of extra empty lines between the files. The command would look like:

mycat [-l <int>] [-v] file1 file2 ... .

In your Main class you need to add a Token object for each argument. In this example we have three Tokens: the number of lines, the verbosity mode and the input files. In addition, you need to add an ApplicationSettings object. This object is used to contain all the arguments.

The source code for these settings is shown in Listing 1. I first declare the sm_main variable and then the three Token variables: sm_verbose, sm_files, sm_lines. The arguments in the constructor of each token object fully describe the expected usage of the Token:

  • Is it a switch or an argument?
  • What is the switch's name (e.g., -v)?
  • What is its type (integer, string, etc.)?
  • Can it appear multiple times (e.g., -l, 1, -l, 2)?
  • Is it a required argument?
  • If not, when the argument is missing:
    1. Is there an environment variable to provide the value?
    2. Is there a default value?
A static initializer adds the Token variables to the ApplicationSettings variable. By the time the main() function of your application is reached, the ApplicationSettings object knows everything about the syntax of your command line utility.

Listing 2 shows the main program of my example. The first line after the try statement calls the parseArgs() method of the ApplicationSettings object. The actual command line arguments are passed as an argument to the object. When the syntax is incorrect, a usage message is printed and an exception is thrown. Otherwise, the Token objects are set to contain appropriate values. For instance, when the -v option is present, the sm_verbose object will be set. Later, when its getValue() method is called, it will return true.

In a similar fashion, if two files are passed as arguments, let's say foo.cc and bar.cc, the sm_files Token will be set appropriately. Its getValue(0) method will return foo.cc, its getValue(1) method will return bar.cc.

Now compile the example with your favorite development environment and run the resulting code without passing any arguments. You should get the usage message in Listing 3. But wait a minute: you never wrote code to print usage messages; what's going on here? It's very simple. The framework uses the same code that defines the expected Tokens to generate usage statements. Kiss the ugly, always-out-of-date, static String statements that describe the usage of the utility goodbye.

Now let's run the program again with some decent arguments. Let's say we run it with arguments "-v foo.cc bar.cc". The program prints the arguments correctly. Though we didn't pass any value for the -l switch, the Token returns 0. This is the expected behavior because the default value of the sm_lines Token is indeed 0.

Why Use the Framework?
By now some of the advantages of the framework should be obvious to you. The error-prone while and switch statements that usually parse the arguments have been replaced by a few very readable statements.

These statements:

  • Document the usage of the command line utility
  • Encapsulate the settings so they can be used by the rest of the program
  • Automatically generate usage messages when the user enters incorrect syntax:
    1. Missing arguments
    2. Unexpected arguments
    3. Wrong types of arguments

The stated advantages speed up the original development of any command line utility. They allow the developer to jump to the real code as soon as possible. At the same time, they provide immediate access to the command line settings and usage messages.

Where the framework really shines is in the area where most of a developer's time is spent: software maintenance. If a command line utility is successful, users will ask for changes and improvements. Many of them will translate to more command line options or change the syntax of existing ones. The framework makes adding and modifying options trivial and safe. Compile-time messages will save the developer from runtime embarrassment.

Finally, the framework is extensible. One can define new types of switches that accommodate new data types or anything else a developer desires.

At this point you can go ahead, download the code and start using it in your own applications. The next few sections discuss the design of the framework.

The StringArrayIterator Class
The StringArrayIterator class is a utility class (see Listing 4). It encapsulates an array of strings and a position inside the array. The get() method returns the String at the current position. The moveNext() operation on the array allows the programmer to advance the current position to the next string. The EOF() operation determines when the end of the array has been reached.

The ApplicationSettings object contains a StringArrayIterator object. It gets initialized from the command line arguments.

The Token Class
The Token class, shown in Listing 5, is an abstract class. Each Token object contains a description of an argument or a switch. After a successful parsing it also contains the value or values that were provided for the argument in the command line.

During the parsing phase, the most important methods of the Token class are the parseSwitch() and parseArgument() methods. Both of them take the StringArrayIterator object with the command line arguments as input. If the current command line argument is recognized, three things occur: it's parsed, the pointer of the StringArrayIterator object is moved and a value of true is returned. If it's not recognized, a value of false is returned.

The values that correspond to this switch or argument are stored in a Vector of objects. Subclasses determine their class. For instance, the StringToken subclass will have String objects, and the IntegerToken subclass will contain Integer objects.

While the program is running, the values are accessible using the getValue(int) and getValue() operations.

Figure 1
Figure 1:  A UML class diagram of the parsing framework

Token Subclasses
A Token subclass encapsulates arguments of a specific type. For example, there's a StringToken, an IntegerToken, etc. Since most of its methods have a generic implementation, each Token subclass has very few methods to implement.

Listing 6 presents the implementation for the class StringToken. A few more subclasses are provided in the downloaded code. You can extend the framework by implementing more subclasses.

The ApplicationSettings Object
The ApplicationSettings object puts everything I've discussed so far together (see Listing 7). It contains all the Token objects and initiates the parsing algorithm. The user triggers the parsing by calling the parseArgs() method.

The command line arguments are assigned to the StringArrayIterator member of the class. Then, for every command line argument, each Token object is called and asked to parse it as either an option or an argument.

If no Token object can parse the argument, a usage message is printed by iterating through the Tokens and calling their printUsage() and printUsageExtended() methods. Both methods take an OutputStream as an argument. They print their output to this stream.

Pure Java and Impurities
Almost all the code is pure Java. Since pure Java doesn't provide support for environment variables and assertions, I had to use the functions provided in my environment, the Win32 Virtual Machine.

These few lines of code are carefully isolated in the util.java file shown in Listing 8. In a pure Java environment you can comment out three lines of code from this file. You don't get assertions and support for initialization of arguments from environment variables. Otherwise, everything else works as advertised.

Limitations
The framework doesn't provide support for complex scenarios. For instance, there's no support for switches that depend on each other. You can't dictate that the -t option can appear if and only if the -p option appears. You'd have to implement such checks yourself after the arguments were parsed.

Conclusion
In this article I presented an extensible Java framework. The framework simplifies the development and maintenance of code that parses the arguments of command line utilities and tools.

The framework doesn't provide support for complex scenarios. Still, my experience is that the framework covers most common cases. I expect that it will be as useful for Java development as it has been for C++.

Reference
P. Kougiouris (1997). "Yet Another Command-Line Parser." C/C++ Users Journal, Vol. 15, No. 4, April.

About the Author
Panos Kougiouris has ten years' experience in software development for high-tech companies. For the past three years he has been at Healtheon, a Silicon Valley startup, and he has held technical positions with Oracle and Sun Microsystems. Panos holds computer science degrees from the University of Illinois at Urbana-Champaign and the University of Patra, Greece. He can be reached at [email protected]

	

Listing 1. The mycat example declaration of tokens
 
import psk.cmdline.*; 

public class Main 
{ 
  // Initialize the applicationSettings and 
  // the tokens objects 
  static ApplicationSettings sm_main = 
                 new ApplicationSettings(); 
  static BooleanToken 
    sm_verbose = new BooleanToken( 
                  "v",   // switch name 
                  "verbose turned on or off", // message 
                  "",    // environment variable 
                  TokenOptions.optSwitch, // options 
                  false);   // default value 
  static IntegerToken 
    sm_lines = new IntegerToken( 
                  "l", 
                  "Number of empty lines to insert", 
                  "NUM_OF_LINES", 
                  TokenOptions.optSwitch, 
                  0); 
  static StringToken 
    sm_files =   new StringToken( 
                   "", 
                   "Test cases", 
                   "", 
                   TokenOptions.optArgument| 
                   TokenOptions.optMultiple| 
                 TokenOptions.optRequired, 
                   ""); 
  // Add all the token objects to the 
  // ApplicationSettings object 
  static { 
    sm_main.addToken(sm_verbose); 
    sm_main.addToken(sm_lines); 
    sm_main.addToken(sm_files); 
  } 

Listing  2.  The mycat example main() function
 
public static void main (String[] args) 
  { 
    try { 
      sm_main.parseArgs(args); 
  
      // Let's see what we 've got 
      System.out.println(sm_verbose.getValue() ? 
"verbose" : "not verbose"); 
      System.out.println("lines: " + Integer.toString 
(sm_lines.getValue(0))); 
      for (int i = 0; i < sm_files.NumberOfValues(); 
i++) 
        System.out.println("tests: " + sm_files.getValue(i)); 
    } catch (Exception ex) { 
  
    } 
  } 

Listing  3.  Output of the mycat example when no arguments are passed
 
Error: missing required argument. Name: 

Usage: program [-v ] [-l <Integer>]  <String> ... 

        -v 'verbose turned on or off'  Default: 
false 
        -l 'Number of empty lines to insert' 
Environment: 
$NUM_OF_LINES Default 
: 0 
         'Test cases' 

Listing 4.  The StringIterator class
 
// Copyright (c) 1998 Panos Kougiouris All 
Rights Reserved 
package psk.cmdline; 

/* 
 * This is a utility class. It encapsulates an array 
 * and an index that points to the current object 
 * 
 * @version  1.0,11/01/1998 
 * @author Panos Kougiouris 
 */ 

public class StringArrayIterator 
{ 
 public StringArrayIterator(String[] aStrings) { 
  m_index = 0; 
  m_strings = aStrings; 
 } 
  
 public boolean EOF() { 
  return m_index >= m_strings.length; 
 } 
  
 public void moveNext() { 
  m_index++; 
 } 
  
 public String get() { 
  return m_strings[m_index]; 
 } 
  
 private String[] m_strings; 
 private int      m_index; 
} 

Listing 5. The Token abstract class
 
// Copyright (c) 1998 Panos Kougiouris All Rights 
Reserved 
package psk.cmdline; 

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

/* 
 * Each Token object encapsulates one command 
 * line argumet or switch. 
 * 
 * @version  1.0, 11/02/1998 
 * @author Panos Kougiouris 
 */ 

public abstract class Token 
{ 
 public String name() {return m_name;}; 
  
 public int NumberOfValues() { 
  return m_values.size(); 
 } 
  
    public String extendedName() { 
        if (isSwitch()) { 
            return "-" + name(); 
        } else { 
            return name(); 
        } 
    } 
  
 //----------------------------------------------- 
 // Subclasses should implement these 
 //----------------------------------------------- 
  
 public abstract Object toObject(String lexeme); 
  
 // All but bool (where merely the appearence of 
the flag 
 // signifies the existence) return true; 
 public boolean hasOneOrMoreArgs() {return true;}; 
  
 public abstract String type(); 
  
 // Also implement these two methods 
 // <Type> getValue(int i); 
 // <Type> getValue(); 
  
 protected Token( 
  String a_name, 
  String a_message, 
  String a_environment_variable, 
  int aTokenOptions  // of type TokenOptions 
  ) { 
  m_name = a_name; 
  m_message = a_message; 
  m_env_variable = a_environment_variable; 
  m_flags = aTokenOptions; 
  m_firstTime = true; 
  m_values = new Vector(1); 
 }; 
  
 //----------------------------------------------- 
 // These methods are used by the ApplicationSettings class 
 // Thast' why they are protected 
 //----------------------------------------------- 
  
 // If we match the switch 
 // we parse as many command line arguments as they 
apply to this 
 // switch and then return just before the next one 
we do not 
 // recognize 
 protected boolean ParseSwitch(StringArrayIterator 
cmdLineArgs) 
throws Exception { 
  if (this.isArgument()) return false; 
  if ((this.isUsed()) && (!this.allowsMultipleValues())) 
return 
false; 
  if (cmdLineArgs.get().substring(1).indexOf(name()) 
!= 0) return 
false; 

  // after the match what remains e.g. if we are -t and 
  // argument is -tom then rest == 'om' 
  String lexeme = cmdLineArgs.get().substring(1 + 
name().length()); 
  if (lexeme.length() == 0) { 
   // the "-t foo" or "-t" case 
   if (this.hasOneOrMoreArgs()) { 
    // move to the "foo" 
    cmdLineArgs.moveNext(); 
    if (!cmdLineArgs.EOF()) 
     lexeme = cmdLineArgs.get(); 
    else { 
     String str = new String("Argument expected for option "); 
     str += this.extendedName(); 
     throw new Exception(str); 
    } 
   } 
  } else { 
   // "-tfoo" case 
   if (!this.hasOneOrMoreArgs()) { 
    String str = new String("No Argument expected for option "); 
    str += this.name(); 
    throw new Exception(str); 
   } 
  } 
  
  this.AddValueFromLexeme(lexeme); 
  this.setUsed(); 

        /* 
         * If you comment out these lines then 
         * "-l 1 2 3" will be permitted. Now this should be 
         * "-l 1 -l 2 -l 3" 
         * 
        if (allowsMultipleValues()) { 
      cmdLineArgs.moveNext(); 
      // if it supports multiple parse more arguments 
      while ((!cmdLineArgs.EOF()) && 
          (!isASwitch(cmdLineArgs.get()))) { 
       this.AddValueFromLexeme(cmdLineArgs.get()); 
       cmdLineArgs.moveNext(); 
      } 
      cmdLineArgs.movePrevious(); 
        } 
        */ 
  
  return true; 
 } 
  
 protected boolean parseArgument(StringArrayIterator 
cmdLineArgs) { 
  if (isSwitch()) return false; 
  if ((isUsed()) && 
   (!allowsMultipleValues())) return false; 
  
  // if it supports multiple parse more arguments 
  while ((!cmdLineArgs.EOF()) && 
      (!isASwitch(cmdLineArgs.get()))) { 
   this.AddValueFromLexeme(cmdLineArgs.get()); 
   this.setUsed(); 
   cmdLineArgs.moveNext(); 
   if (!allowsMultipleValues()) break; 
  } 
  
  return true; 
 } 
  
 protected void printUsage(java.io.PrintStream str) { 
  if (!this.isRequired()) str.print( "["); 
  str.print(this.extendedName() + " "); 
  str.print(this.type()); 
  if (this.allowsMultipleValues()) str.print(" ..."); 
  if (!this.isRequired()) str.print( "]"); 
  str.print(" "); 
 } 
  
 protected void printUsageExtended(java.io.PrintStream 
str) { 
  str.print("\t"); 
  str.print(this.extendedName() + " "); 
  str.print("'" + this.m_message + "' "); 
  if (hasEnvironmentVariable()) { 
   str.print(" Environment: $" + this.m_env_variable); 
  } 
  if (!this.isRequired()) { 
   str.print(" Default: "); 
   str.print(this.getDefaultValue()); 
  } 
  str.println(); 
 } 
  
 protected boolean hasEnvironmentVariable() 
 { 
  return this.m_env_variable.compareTo("") != 0; 
 } 
  
 protected String getEnvironmentVariable() { 
  return this.m_env_variable; 
 } 
  
 protected boolean isRequired() { 
  return (m_flags & TokenOptions.optRequired) == 
TokenOptions.optRequired; 
 }; 
  
 protected boolean isSwitch() { 
  return !isArgument(); 
 }; 
  
 protected boolean isArgument() { 
  return (m_flags & TokenOptions.optArgument) == 
TokenOptions.optArgument; 
 }; 
  
 protected boolean allowsMultipleValues() { 
  return (m_flags & TokenOptions.optMultiple) == 
TokenOptions.optMultiple; 
 }; 
  
 protected boolean isUsed() { 
  return (m_flags & TokenOptions.optAlreadyUsed) == 
TokenOptions.optAlreadyUsed; 
 }; 
  
 protected void setUsed() {m_flags |= 
TokenOptions.optAlreadyUsed;}; 
  
 protected void AddValueFromLexeme(String lexeme) { 
  if (m_firstTime) { 
   SetValueFromLexeme(lexeme, 0); 
  } else { 
            util.assert(this.allowsMultipleValues(), ""); 
   m_values.addElement(toObject(lexeme)); 
  } 
  m_firstTime = false; 
 } 
  
 protected void SetValueFromLexeme(String lexeme, int i) { 
  m_values.setSize(java.lang.Math.max(m_values.size(), 
i + 1)); 
  m_values.setElementAt(toObject(lexeme), i); 
 } 
  
 protected String getDefaultValue() { 
  return m_defaultValue.toString(); 
 } 
  
 protected void setDefaultValue(Object obj) { 
  m_defaultValue = obj; 
  m_values.setSize(java.lang.Math.max(m_values.size(),1)); 
  m_values.setElementAt(obj, 0); 
 } 
  
 protected static boolean isASwitch(String arg) { 
  return (arg.charAt(0) == '-'); 
 } 

 protected String                   m_name; 
 protected String                   m_message; 
 protected int                      m_flags; 
 protected String                   m_env_variable; 
 protected Vector                   m_values; 
 protected Object                   m_defaultValue; 
 protected boolean       m_firstTime; 
} 

Listing 6.  The StringToken class, an example of a sublcass of the Token class
 
// Copyright (c) 1998 Panos Kougiouris All Rights Reserved 
package psk.cmdline; 

/* 
 * The Implemetation of Tokens for Strings 
 * 
 * @version 1.0, 11/02/1998 
 * @author  Panos Kougiouris 
 */ 

public class StringToken extends Token 
{ 
 public StringToken( 
  String a_name, 
  String a_message, 
  String a_environment_variable, 
  int aTokenOptions, 
     String a_def_value) { 
  super(a_name, a_message, a_environment_variable, 
aTokenOptions); 
  setDefaultValue(a_def_value); 
 } 
  
 public String type() { 
  return "<String>"; 
 } 
  
 public String getValue() { 
  return getValue(0); 
 } 
  
 public String getValue(int i) { 
  return (String)m_values.elementAt(i); 
 } 
  
 public Object toObject(String lexeme) { 
  return lexeme; 
 } 
} 

Listing 7.  The ApplicationSettings class source code
 
// Copyright (c) 1998 Panos Kougiouris All Rights 
Reserved 
package psk.cmdline; 

/* 
 * The class that contains all the tokens and 
 * initiates the parsing 
 * 
 * @version  1.0, 11/04/1998 
 * @author Panos Kougiouris 
 */ 
  

public class ApplicationSettings 
{ 
 public ApplicationSettings() { 
  this(ApplicationSettingsOptions.optDoNotIgnoreUnknown); 
 } 
  
 public ApplicationSettings 
(int aApplicationSettingsOptions) { 
  m_argDescriptions = new java.util.Vector(); 
  m_flags = aApplicationSettingsOptions; 
 } 
  
 public void addToken(Token argum) { 
  for (int i = 0; i < m_argDescriptions.size(); i++) { 
   Token argDesc = ((Token)m_argDescriptions.elementAt(i)); 
  
   //Make sure we have no argument clash 
   if (argDesc.name().compareTo(argum.name()) == 0) { 
    System.err.print("ApplicationSettings ERROR: option \""); 
    System.err.print(argum.name()); 
    System.err.println("\"is used more than once"); 
    System.exit(-1); 
   } 
  
   // make sure there is only one that is non switch 
   if (!argDesc.isSwitch() && !argum.isSwitch()) { 
    System.err.print("ApplicationSettings ERROR: arguments 
defined in both '"); 
    System.err.print(argum.name()); 
    System.err.print("' and '"); 
    System.err.println(argDesc.name() + "'"); 
    System.err.println("Arguments should be defined 
only once."); 
    System.exit(-2); 
   } 
  } 
  m_argDescriptions.addElement(argum); 
 } 
  
 public void parseArgs(String[] args) throws Exception { 
  m_cmdLineArgs = new StringArrayIterator(args); 
  
  setEnvironmentValues(); 
  parseInternal(); 
 } 
  
 public void printUsage(String reason) throws Exception { 
  // Print the first line 
  System.err.print("Error: "); 
  System.err.println(reason + "\n"); 
  // Print the usage line 
  System.err.print("Usage: "); 
  System.err.print(m_programName + " "); 
  for (int i = 0; i < m_argDescriptions.size(); i++) { 
   Token arg = (Token)m_argDescriptions.elementAt(i); 
   arg.printUsage(System.err); 
  } 
  System.err.println("\n"); 
  
  // Print the explanations 
  for (int i = 0; i < m_argDescriptions.size(); i++) { 
   Token arg = (Token)m_argDescriptions.elementAt(i); 
   arg.printUsageExtended(System.err); 
  } 
  throw new Exception(reason); 
 } 
  
 //------------------------------------------------ 
  
 // This functions should be called only once 
 protected void parseNonSwitch() throws Exception { 
  for (int i = 0; i < m_argDescriptions.size(); i++) { 
   Token argDesc = 
((Token)m_argDescriptions.elementAt(i)); 
  
   if (!argDesc.parseArgument(m_cmdLineArgs)) continue; 
  
   // here should be the end... 
   if (!m_cmdLineArgs.EOF()) { 
    this.printUsage("too many commeand line arguments."); 
   } 
   return; 
  } 
  
  String str = "Unexepected argument "; 
  str += m_cmdLineArgs.get(); 
  if (!ignoreUnknownSwitches()) 
   this.printUsage(str); 
 } 
  
 protected void parseInternal() throws Exception { 
  // skip the name of the program 
  m_programName = "program"; 
  
  while (!m_cmdLineArgs.EOF()) { 
            try { 
       if (Token.isASwitch(m_cmdLineArgs.get())) { 
        this.parseSwitch(); 
       } else { 
        this.parseNonSwitch(); 
        break; 
       } 
            } catch (Exception ex) { 
                String str = ex.getMessage(); 
                if (ex.getClass() == 
NumberFormatException.class) { 
                    str = str + " "; 
                    str = str + " wrong argument type"; 
                } 
    // most likely 'argument expected' 
    this.printUsage(str); 
   } 
   m_cmdLineArgs.moveNext(); 
  } 
  
  for (int i = 0; i < m_argDescriptions.size(); i++) { 
   Token argDesc = 
((Token)m_argDescriptions.elementAt(i)); 
   if (!argDesc.isUsed() && argDesc.isRequired()) { 
    String str; 
    str = "missing required argument. Name: "; 
    str += argDesc.extendedName(); 
    this.printUsage(str); 
   } 
  } 
 } 
  
 protected void parseSwitch() throws Exception { 
  int i = 0; 
  for (i = 0; i < m_argDescriptions.size(); i++) { 
   Token argDesc = 
((Token)m_argDescriptions.elementAt(i)); 
   if (argDesc.ParseSwitch(m_cmdLineArgs)) return; 
  } 
  
  // We tried all the tokens and no one recognized 
  if (i >= m_argDescriptions.size()) { 
   String str= new String("Unknown option "); 
   str += m_cmdLineArgs.get(); 
   if (!ignoreUnknownSwitches()) 
    this.printUsage(str); 
  } 
 } 
  
 protected void setEnvironmentValues() { 
  for (int i = 0; i < m_argDescriptions.size(); i++) { 
   Token argDesc = 
((Token)m_argDescriptions.elementAt(i)); 
   if (argDesc.hasEnvironmentVariable()) { 
    String str = util.GetEnvVariable 
(argDesc.getEnvironmentVariable()); 
    if (str.length() != 0) { 
     argDesc.SetValueFromLexeme(str, 0); 
    } 
   } 
  } 
 } 
  
 protected boolean ignoreUnknownSwitches() { 
  return (m_flags & 
ApplicationSettingsOptions.optIgnoreUnknown) != 0; 
 } 
  
 // Data members 
 protected StringArrayIterator m_cmdLineArgs; 
 protected String              m_programName; 
 protected java.util.Vector    m_argDescriptions; 
// Vector of Argv objects 
 protected int                 m_flags; 
} 

Listing 8.  The util class (contains nonPure Java code.
 
If commented out the resulting code is Pure Java but the 
functionality is reduced) 
// Copyright (c) 1998 Panos Kougiouris All Rights Reserved 
package psk.cmdline; 

import com.ms.wfc.util.Debug.*; 
/* 
 * Java purists will want to comment out a few lines of code 
in this file 
 * 
 * 
 * @version  1.0,11/01/1998 
 * @author Panos Kougiouris 
 */ 

public class util 
{ 
    // If you do not tatrget the Microsoft Win32 VM 
 // comment out the following few lines. Always return 
    // "" from this function. It will just remove the 
    // env. variable functionality 
 // If you know how to get an env. variable in 
 // Pure Java pls e-mail me [email protected] 
    static public String GetEnvVariable(String name) { 
        StringBuffer strBuf = new StringBuffer(200); 
        int ret = com.ms.win32.Kernel32.GetEnvironmentVariable( 
               name, strBuf, 200); 
        if (ret != 0) { 
            return strBuf.toString(); 
        } else { 
            return ""; 
        } 
    } 
  
    // Just comment the line out for pure java environments 
    static public void assert(boolean cond, String msg) { 
        com.ms.wfc.util.Debug.assert(cond, msg); 
    } 
} 

  

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