out of array bounds error

See attached:

the print ln show that the array should be 4 by 3, but
it give an error even when I am trying to set a value at [0][1]

the source code shown is from FSA.java

Quote:

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Originally Posted by Iliketofrolic666

See attached:

the print ln show that the array should be 4 by 3, but
it give an error even when I am trying to set a value at [0][1]

the source code shown is from FSA.java

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Code:

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

public class FSA{
  private String machineName;      //name of machine
  private int numStates;                //number of states
  private String alphabet;        //a list of distinct symbols
  private int[][] transitions;    //numStates-by-length_of_alphabet
  private String tape;                  //a string over the alphabet
  private int start;              //start-state
  private boolean[] acceptStates;  //set of accept-states

 
  //Use a Scanner to open the file whose name is fileName.
  //Input the FSA from this file
  public FSA(String fileName) throws IOException
  {
              FileReader freader = new FileReader(fileName);
 
              Scanner scanner = new Scanner(freader);
             
             
              //Read in file header
              machineName = scanner.nextLine();
              numStates = scanner.nextInt();
              scanner.nextLine();
              start = scanner.nextInt();
              scanner.nextLine();
              alphabet = scanner.nextLine();
             
              transitions = new int[numStates][alphabet.length()];
             
              System.out.println(alphabet.length()+"    "+numStates);
              int i,j,k;
              do{
                        i = scanner.nextInt();//state
                        j = scanner.nextInt();//transition
                        k = scanner.nextInt();//new state
                        scanner.nextLine();
                        if (-1 != i )
                        {
                                  System.out.println("  i: "+i+"  alphabet.charAt():  "+alphabet.charAt(j)+"  j: "+j+"  K:  "+k);
                                transitions[i][alphabet.charAt(j)] = k;
                        }
                       
              } while (-1 != i);
             
         
              acceptStates = new boolean[numStates];
              for (int temp = 0; temp < numStates; temp++)
              {
                        acceptStates[temp] = false;
              }
              while (scanner.hasNextLine())
              {
                        String str = scanner.nextLine();
                        if (-1 != str.indexOf(-1)){break;}
                        for (int temp = 0; temp < numStates; temp++)
                        {
                                    if (-1 != str.indexOf(temp))
                                    {
                                              acceptStates[temp] = true;
                                    }
                        }
              }
             
  }


  //Display the FSM as show on the next page
  public void displayMachine()
  {
            System.out.println("Machine Name: "+machineName);
            System.out.print("Set of States: {");
            /*for (int i = 0; i < numStates; i++)
            {
                      System.out.print(i,
            }*/
  }

  //Return the machineName to caller
  public String name()
  {
              return machineName; 
  }

  //Return number of states to caller
  public int numberOfStates() 
  {
              return numStates;
  }

  //Return alphabet back to caller
  public String alphabet()
  { 
              return alphabet;
  }

  //Return start state back to caller
  public int start()
  {
              return start;
  }

  //Return next state if in current state and see symbol
  public int nextState(int current, char symbol)
  {
            return transitions[current][alphabet.indexOf(symbol)];         
  }

  //Return true or false if k is or is or is not a final state.
  public boolean finalState(int k)
  {
              return acceptStates[k];
  }

  //Process tape, display transitions and determine if accept or reject tape
  public void processTape(String tape)
  {
             
  }
}

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If you look at the stack trace, you will see you are out of bounds because you aren't trying to set it at [0][1], you are trying to set it at [0][49]

This is your problem:

transitions[i][alphabet.charAt(j)] = k;

alphabet.charAt(j) returns a character, not an integer. You are using the unicode value of alphabet.charAt(j) which is causing the error