Thread: binarySearch troubles

Hi,
Im making a program that scrambles a word into all the possible permutations. So i swap letters in the string randomly to make a new string. I then want to search the array to see if that string allready exist in the array, however when i use binarySearch it says it cannot find the method. Here is my code:

import java.util.Arrays;
import java.util.Random;
import java.lang.StringBuilder;
public class StringScramble
{
 
    public static void main (String[] args)
    {
    StringBuffer myString = new StringBuffer ("abc");
    int length = myString.length();
    int permu = 1;
    Random randomGenerator = new Random();
 
    while (length > 1){
        permu *= length;
        length--;
        System.out.println(permu);
        }
 
    int arrayNum = 0;        
    String[] array = new String[permu];
    array[arrayNum] = myString.toString();
    arrayNum++;
 
        while(arrayNum < permu){
            //initialize variables
            int length2 = myString.length();
            int randomInt1 = randomGenerator.nextInt(length2);
            char swap1 = myString.charAt(randomInt1);
            int randomInt2 = randomGenerator.nextInt(length2);
            char swap2 = myString.charAt(randomInt2);
            char temp;
 
            //the switch
            temp = swap1;
            swap1=swap2;
            swap2=temp;
 
            //set it in the string
            myString.setCharAt(randomInt1, swap1);
            myString.setCharAt(randomInt2, swap2);
 
            int search = array.binarySearch(array, myString.toString());
 
            if (!(search>=0)){
            array[arrayNum]= myString.toString();
            arrayNum++;
        }
    }
}
}

Also, if someone knows of a easier way to find permutations, that would be helpful too

Thanks
Joel

Hey,
I made a new method for it:

import java.util.Arrays;
import java.util.Random;
import java.lang.StringBuilder;
public class StringScramble
{
 
    public static void main (String[] args)
    {
    StringBuffer myString = new StringBuffer ("abc");
    int length = myString.length();
    int permu = 1;
    Random randomGenerator = new Random();
 
    while (length > 1){
        permu *= length;
        length--;
        System.out.println(permu);
        }
 
    int arrayNum = 0;        
    String[] array = new String[permu];
    array[arrayNum] = myString.toString();
    arrayNum++;
 
        while(arrayNum < permu){
            //initialize variables
            int length2 = myString.length();
            int randomInt1 = randomGenerator.nextInt(length2);
            char swap1 = myString.charAt(randomInt1);
            int randomInt2 = randomGenerator.nextInt(length2);
            char swap2 = myString.charAt(randomInt2);
            char temp;
 
            //the switch
            temp = swap1;
            swap1=swap2;
            swap2=temp;
 
            //set it in the string
            myString.setCharAt(randomInt1, swap1);
            myString.setCharAt(randomInt2, swap2);
 
            int search = checkArray(array, myString.toString(), permu);
 
            if (search>0){
            array[arrayNum]= myString.toString();
            arrayNum++;
        }
    }
        System.out.println(array[0]);
        System.out.println(array[1]);
        System.out.println(array[2]);
        System.out.println(array[3]);
        System.out.println(array[4]);
        System.out.println(array[5]);
 
}
 
    public static int checkArray(String[] array, String checkee, int permu){
        int counter = 0;
        int returner=0;
                System.out.println(array[0]);
        System.out.println(array[1]);
        System.out.println(array[2]);
        System.out.println(array[3]);
        System.out.println(array[4]);
        System.out.println(array[5]);
        while (counter<permu){
            if (checkee != array[counter]){
               returner++;
            }
            counter++;
            }
        System.out.println("Returner:"+returner);
        return returner;
        }
}

However, each time it adds to counter, even if it is equal to the value. How can i fix this?
Joel

So, the method checks to see if the string matches with a slot in the array, or array[counter]. If the string and the array slot are not equal, it adds 1 to the value that gets returned. If the value that gets returned is greater than 0, then it adds the new permutation to the array... i realize this is kindof a spaghetti code...

My problem is, that in the method that checks if the string matches the array slot, it adds 1 to the return value, even if it is equal to it... So it will always add it to the array even though its already in it...

public static int checkArray(String[] array, String checkee, int permu){
        int counter = 0;
        int returner=0;
        while (counter<permu){
            if (checkee != array[counter]){
               returner++;
            }
            counter++;
            }
        System.out.println("Returner:"+returner);
        return returner;
        }
}

Did you try debugging this part of your code?

No, how do i do that? (I use BlueJ, btw)

Well, you read your IDE documentation or if you can't find, try using System.out.println() after consecutive statements and try to find where actually the problem is.

ThankYou, I figured out what was wrong with it.