Thread: 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.

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

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.

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

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.

Originally Posted by BenjaminJ

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

Originally Posted by GregBrannon

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.