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Thread: if statement - might have problem with char to String casting?

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    Default if statement - might have problem with char to String casting?

    import java.io.IOException;
    import java.util.*;
    public class Guesser {
    	public static void main(String[] args) throws IOException {
     
    		char[] alphabet = "abcdefghijklmnopqrstuvwxyz1234567890 .,:;'-".toCharArray();
    		Scanner sc = new Scanner(System.in);
    		System.out.println("Input three characters"); // gather three letter word to be matched with randomly generated chars
    		String characters = sc.next();
     
     
    	for (int i=0; ; i++) {
     
    			int x = (int) (Math.random() * alphabet.length);  // randomly generate a char from the char array
    			int y = (int) (Math.random() * alphabet.length);
    			int z = (int) (Math.random() * alphabet.length);
     
    			char letterOne = (alphabet[x]);
    			String firstPlace = String.valueOf(letterOne); // convert generated char to string for concatenation
    			char letterTwo =(alphabet[y]);
    			String secondPlace = String.valueOf(letterTwo);
    			char letterThree =(alphabet[z]); 
    			String thirdPlace = String.valueOf(letterThree);
    			System.out.println(firstPlace + secondPlace + thirdPlace);
     
    			if (characters == (firstPlace + secondPlace + thirdPlace )) {
     
    				System.out.println("That took " + i + " tries." );
    				break; // stop the program when it finds the inputted string
    			}
     
     
    		}
     
    	}
    }

    I'm writing a program which will take a three letter word (for now) and then try to guess the word over and over again until it finds it, then print the word and the amount of tries it took to find it.

    The problem: at the moment the program will find the word but not break out of the for loop when it does. I think it doesn't like the char to String conversion somewhere along the line. There must be a quick fix that I'm missing.


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    Default Re: if statement - might have problem with char to String casting?

    Strings can not be compared using the "==" operator. If you want to compare Strings you have to use the equals() method.

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    BenjaminJ (August 5th, 2014)

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    Default Re: if statement - might have problem with char to String casting?

    Oh! Excellent. That totally slipped my mind. Why is not giving me an error, in that case? Is there any way of modifying this code so the user can input a string of any length they choose? I assume that would mean I would have to either a) create infinite variables or b) create user generated variables (I don't know if they exist)
    Last edited by BenjaminJ; August 3rd, 2014 at 08:57 AM.

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    Default Re: if statement - might have problem with char to String casting?

    Is there any way of modifying this code so the user can input a string of any length they choose?
    Yes, that is possible, and No you wouldn't create infinite variables. You can create an array of the required length after the length of the String is known or you could use an ArrayList which will grow as needed. StringBuilder might also be a useful tool as you go through the "guessing" part, but I'm not sure.

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    Default Re: if statement - might have problem with char to String casting?

    So I'd have the array which would have a .length as the amount of items as chars inputted by the user? Then what would I do with that array? Surely there'd be an amount of possibilities which I'd need to account for without knowing what they are. Could you mock up a quick example of the array?

    Thanks

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    Default Re: if statement - might have problem with char to String casting?

    Then what would I do with that array?
    The same as you were doing with 3 letters scaled up to the number of characters entered: test all possible permutations until the right one is found.
    Surely there'd be an amount of possibilities which I'd need to account for without knowing what they are.
    The number of permutations can be calculated for a specified number of items.
    Could you mock up a quick example of the array?
    No mocking necessary. The String class provides a method that returns an array containing the characters of the String object.

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    BenjaminJ (August 5th, 2014)

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    Default Re: if statement - might have problem with char to String casting?

    Quote Originally Posted by BenjaminJ View Post
    Why is not giving me an error, in that case?
    Because it isn't an error. The "==" operator is perfectly valid in this context because it is comparing identities, not equality. (Even if this is not what you want to do at runtime.) Sometimes we don't need true equality, and sometimes we do. This is why Object.equals() can be overridden as it is for String.

    Nice ref: java - What is the difference between identity and equality in OOP? - Stack Overflow

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    BenjaminJ (August 5th, 2014)

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    Default Re: if statement - might have problem with char to String casting?

    Quote Originally Posted by GregBrannon View Post
    The String class provides a method that returns an array containing the characters of the String object.
    Would you mind naming the method? I'm only just starting to learn the String class.

    And thanks jdv for the information, much appreciated.

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    Default Re: if statement - might have problem with char to String casting?

    How about going to the Java API and looking at all the methods and see which one returns a char array.
    Improving the world one idiot at a time!

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