turning method to OO

[steve low]

Hi guys

im a newbie to Java and in workshops what were doing is turning the below code to OO making it simipler. I was wondeirng if sumone if someone can turn the below code to OO soo i can get an idea of how code is turned into OO.

player: while (!false) {
try {
System.out.println(" human players?");
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
String s = in.readLine();
h = Integer.parseInt(s);
if (nop - h < 0)
throw new UnsupportedFlavorException(null);
break player;
} catch (Exception e) {
System.out.println("number of humans ");
}
}

Thanks alot

Steve

[Ernest Friedman-Hill]

Hi Steve,

Individual methods aren't really "object-oriented" or not; object orientation is a property of entire programs, or at least of whole groups of classes. There are a number of problems with this code, but in no sense could you "make this OO" and improve it. At some level, all code, OO or not, has to execute a series of statements to get work done. I/O code like this, especially, more or less looks this way, and there isn't much you can do to change it.

While we're here, I could point out a few things really wrong with this code:

- "while (!false)" is needlessly complex; why not "while (true)" ?
- short, meaningless variable names make code hard to understand
- null message parameter to exception is asking for trouble; why not "", or no parameter?
- Misuse of DataFlavorException type, which is related to drag-and-drop; use IllegalArgumentException
- Terrible misuse of exception handling in general; throwing and catching an exception within a single method is silly. Just use "if/then!"
- unnecessary loop label just adds to the confusion.

[steve low]

Hi

Im having problems using the if and then. please show me an example of how I can turn the below code into a better if statement so I can understand how its done. Thanks alot

    if (nop - h < 0)
throw new UnsupportedFlavorException(null);
break player;
} catch (Exception e) {
System.out.println("number of humans ");
}
}   

[Ernest Friedman-Hill]

If I understand correctly what's happening here, you're just trying to prompt the user for a valid number which is less than or equal to "nop". I might write that like this (if I needed to write code that worked in JDK 1.4, as yours would; in JDK 1.5, you could use the "Scanner" class to simplify a little.)

BufferedReader in = new BufferedReader(new InputStreamReader(System.in), 1);
int h = -1;
do {
    try {
        System.out.print("Human players? ");
        System.out.flush();
        String s = in.readLine();
        if (s == null) System.exit(0);
        h = Integer.parseInt(s);
    } catch(NumberFormatException nfe) {
        // Ignore it, try again; 
    }
} while (h < 0 || (nop - h) < 0);

[steve low]

Hi...this method is a flase basically less then 0 or numbers above 5 is a bad number.

heres what ive done its complaining about the the int h =-1 saying its duplicate. not sure what i have to do there and for some reason its complaining about the last syntax } why?

humanplayer: while (!flase) {
try {
System.out.println("How many human players?");
BufferedReader in = new BufferedReader(new InputStreamReader(System.in), 1);

int h = -1; //dupliate variable

do {
try{
System.out.println("Bad number?");
System.out.flush();
String s = in.readLine();
if (s == null) System.exit(0);
h = Integer.parseInt(s);
}catch(NumberFormatException nfe){

}
} while (h < 0 && (nop - h) < 0);

}
} complains about this syntax

[Ilja Preuss]

You should probably show the whole method to help us helps you.

Also please work on your formatting, your code is very hard to read without any indentations.

[steve low]

    public static void main(String[] args) throws InterruptedException {
    int nop = -99;
    int h = -97;
    System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
    System.out.println("Racer");
    System.out.println("  -  simulation on the planet");
    System.out.println("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
    System.out.println();
    while (true) {
      try {
        System.out.println("How many players?");
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String s = in.readLine();
        nop = Integer.parseInt(s);
        if (nop != 2 && nop != 3 && nop != 4 && nop != 5)
          throw new Exception();
        break;
      } catch (Exception e) {
        System.out.println("Bad number of players ");
      }
    }
    
 humanplayers: while (!false) {
      try {
        System.out.println("How many human players?");
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String s = in.readLine();
        h = Integer.parseInt(s);
        if (nop - h < 0)
          throw new UnsupportedFlavorException(null);
        break humanplayers;
      } catch (Exception e) {
        System.out.println("Bad number of humans ");
      }
    }
    
    
 /**   humanplayer: while (!false) {  //this method im having probs with trying to replace it with the top one 
        try {
          System.out.println("How many human players?");
          BufferedReader in = new BufferedReader(new InputStreamReader(System.in), 1);
          
          int  h = -1; // does not like this?
        
          do { 
          try{
          System.out.println("Bad number of players?");
          System.out.flush();
          String s = in.readLine();
          if (s == null) System.exit(0);
          h = Integer.parseInt(s);
          }catch(NumberFormatException nfe){
          
          }
          } while (h < 0 && (nop - h) < 0);
        
  }
    }**/

thats the full code i was going to attempt the true statement after i finsihed the false one.. but i kept on having the error on it. but ive listed the full code. in the above method which im doing it does not like int h = -1; also it complains about the last syntax for some reason? hope this helps
[ October 01, 2006: Message edited by: steve low ]

[Ernest Friedman-Hill]

You can only declare a variable once; "int h = -1" could simply be "h = -1", since h already exists.

But now we are getting into another style issue: methods should never be this long, and you should never reuse variables for many different purposes this way. This should be broken up into multiple small er methods.

Given this issue -- the multiple-declarations problem -- it's clear that this belongs in "Java in General (Beginner)," and not here.

[steve low]

Hi guys

i kinda got my method working but not as i wanted it to basically this method is replacing the old one at the bottom. and what i want it to do
select number of human players.. you have from 1 to 5 but throw an exception if more then 5 and loop allowing the user to select human players again. thats what ive done below. the bottom code is the old code you can have a look and see what im trying to do to it...

     
player: while (!false)        
 try {       
   System.out.println("How many fdfhuman ssplayers?");     
     BufferedReader in = new BufferedReader(new InputStreamReader
(System.in), 1);         
 int  nu = -1;                 
 do {           
   try{          
     System.out.flush();          
      String s = in.readLine();          
            if (nop - nu < 0);          
                 nu = Integer.parseInt(s);       
                    } catch (IOException e) {}       while  (nop - nu < 0);          System.out.println("Bad number of players? ");  
}finally{ 

old code

    humanplayers: while (!false) {      
try {        
System.out.println("select number of humans?");       
 BufferedReader in = new BufferedReader(new InputStreamReader(System.in));       
 String s = in.readLine();       
 h = Integer.parseInt(s);       
 if (nop - h < 0)        
  throw new UnsupportedFlavorException(null);  
      break humanplayers;     
 } catch (Exception e) {       
 System.out.println("Bad number of humans ");     
 }}  

Sorry i thought I ran out of posting within my last one didnt mean to confuse you guys

[ October 02, 2006: Message edited by: steve low ]

[ October 02, 2006: Message edited by: steve low ]

[ October 02, 2006: Message edited by: steve low ]
[ October 02, 2006: Message edited by: steve low ]