Thread: lotto ticket generator help

i can't get it to loop the number of tickets that the user puts in. and right now i keep on getting an ArrayoutofBoundException:0 in my main. i can't see what's wrong with it

import java.io.*;
import java.util.*;
public class Lotto
{
      //*********commandLine1()**********
      public static boolean commandLine1(String str)
      {
        if(!str.equalsIgnoreCase("mm") &&
           !str.equalsIgnoreCase("sl")) return(false);
        else                            return(true);
    }
    //*********commandLine2()**********
    public static boolean commandLine2(String str)
    {
        int i = 0;
        while(i < str.length())
        {
            char c = str.charAt(i);
            if(c < '0' || c > '9') return(false);
            i++;
        }
        return(true);
    }
    //**********random()***************
    public static int random(int a, int b)
    {
        return((int)((b - a + 1)*Math.random() + a));
    }
    //**********superLottoNumbers()*********
    public static int[] superLottoNumbers()
    {
        System.out.println("       Super Lotto      ");
        System.out.println("                         Mega");
        int numZ[] = new int[6];
        for(int h = 0; h <=4; h++)
        {
            numZ[h] = random(1,47);
        }
        numZ[6] = 99;
        Arrays.sort(numZ);
        numZ[6] = random(1,27);  
        return(numZ);
    }
     //**********megaMillionNumbers()*********
    public static int[] megaMillionNumbers()
 
  {
        System.out.println("       Mega Million Lotto      ");
        System.out.println("                      Mega");
        int numZ[] = new int[6];
        for(int i = 0; i <= 4; i++)
        {
            numZ[i] = random(1,56);
        }
        numZ[5] = 99;
        Arrays.sort(numZ);
        numZ[5] = random(1,46);
        return(numZ);
    }
    public static void main(String args[])
    {
        if(commandLine1(args[0]) == false) System.err.println("Not a valid type of Lottery");System.exit(1);
        if(commandLine2(args[1]) == false) System.err.println("Not a valid number of tickets");System.exit(2);
        if(args[1].equals("0"))           System.err.println("Can't print out 0 ticekts.");System.exit(3);
        if(args[0].equalsIgnoreCase("sl"))
        {
          int num[] = new int[7];
          for(int k = 0; k <Integer.parseInt(args[1]) ; k++)
          {
             for(int h = 0; h < 6 ; h++)
             {
                num = superLottoNumbers();  
                System.out.print(num[h]+"   ");
 
  }
          }
        }
       /* if(args[0].equalsIgnoreCase("mm"))
        {
            int num[];
            for(int k = 0; k <Integer.parseInt(args[1]); k++)
            {
                num = megaMillionNumbers();
                for(int i: num) System.out.print(i+"   ");
            }
        }*/
    }
}

Please repost your code between tags (see BB code link below) to retain formatting and make it easier to read.

Copy and paste the full and exact error message. Indicate on which line it occurs.

(args[0]) == false)

Use the equals() method when comparing Strings. The == operator is for primitives.

Where do you test if there are any elements in the args array?

 
import java.io.*;
import java.util.*;
public class Lotto
{
    //*********commandLine1()**********
    public static boolean commandLine1(String str)
    {
        if(!str.equalsIgnoreCase("mm") &&
           !str.equalsIgnoreCase("sl")) return(false);
        else                            return(true);
    }
    //*********commandLine2()**********
    public static boolean commandLine2(String str)
    {
        int i = 0;
        while(i < str.length())
        {
            char c = str.charAt(i);
            if(c < '0' || c > '9') return(false);
            i++;
        }
        return(true);
    }
    //**********random()***************
    public static int random(int a, int b)
    {
        return((int)((b - a + 1)*Math.random() + a));
    }
    //**********superLottoNumbers()*********
    public static int[] superLottoNumbers()
    {
        System.out.println("       Super Lotto      ");
        System.out.println("                         Mega");
        int numZ[] = new int[6];
        for(int h = 0; h <=4; h++)
        {
            numZ[h] = random(1,47);
  }
        numZ[6] = 99;
        Arrays.sort(numZ);
        numZ[6] = random(1,27);
        return(numZ);
    }
     //**********megaMillionNumbers()*********
    public static int[] megaMillionNumbers()
    {
        System.out.println("       Mega Million Lotto      ");
        System.out.println("                      Mega");
        int numZ[] = new int[6];
        for(int i = 0; i <= 4; i++)
        {
            numZ[i] = random(1,56);
        }
        numZ[5] = 99;
        Arrays.sort(numZ);
        numZ[5] = random(1,46); 
        return(numZ);
    }
    public static void main(String args[])
 {
        if(commandLine1(args[0]) == false) System.err.println("Not a valid type of Lottery");System.exit(1);
        if(commandLine2(args[1]) == false) System.err.println("Not a valid number of tickets");System.exit($
        if(args[1].equals("0"))           System.err.println("Can't print out 0 ticekts.");System.exit(3); $
        if(args[0].equalsIgnoreCase("sl"))
        {
          int num[] = new int[7];
          for(int k = 0; k <Integer.parseInt(args[1])-1 ; k++)
          {
             for(int h = 0; h < 6 ; h++)
             {
                num = superLottoNumbers();
                System.out.print(num[h]+"   ");
             }
          }
        }
    }
}

error:
/students/mau1> java Lotto sl
/students/mau1> java Lotto
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at Lotto.main(Lotto.java:67)

The error is occuring on line 67. You need to go to that line, see what array you are trying to read and trace back as to why it has a length of 0.

Also your code is very confusing.

for(int k = 0; k <Integer.parseInt(args[1]) ; k++) {
    for(int h = 0; h < 6 ; h++) {
        num = superLottoNumbers();
        System.out.print(num[h]+" ");
    }
}

Why do you have nested loops? Why are you creating a new array of lotto numbers each time around the inner loop? When h is 0 you creaet an array of numbers and print out the number in position 0. Then h becomes 1 and you create a new array of numbers (throwing away the first set) and print out the number in position 1. Then h becomes 2 etc. Why aren't you creating the array of lotto numbers once?

What you need to do is walk away from the computer. Grab some paper and a pencil. Then draw out what you need to do. Fully plan each tiny itsy-bitsy little step you need to take. Once you are 110% confident you know exactly what the code should do can you go back to the computer and start translating your detailed design into code.