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Thread: Problem with string.compareTo();

  1. #1
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    Thumbs up Problem with string.compareTo();

    I've been having an issue with a lab that I'm doing for school and my professor specifically wants us to use the .compareTo() method for the following code:
    import java.util.*;
     
    public class lab20 {
    	static Scanner in = new Scanner(System.in);
    	public static void main(String[] args)
    	{
    		String[] names = new String[20];
    		int size = 0;
     
    		System.out.print("Enter a name, last name first(Enter 'END' to quit): ");
    		String name = in.nextLine();
    		while (!name.equals("END") && names.length <= 20)
    		{
    			names[size] = name;
    			System.out.print("Enter another name: ");
    			name = in.nextLine();
    			size++;
    		}
    		for (int i = 0; i < size; i++)
    			System.out.println(names[i]);
    		sort(names, size);
     
    		System.out.println();
     
    		for (int i = 0; i <size; i++)
    			System.out.println(names[i]);
    	}
    	public static void sort (String[] names, int size)
    	{
    		int i = 0;
    		int minPos;
    		String temp;
     
    		for (i = 0; i < size; i++)
    		{
    			minPos = minimunPosition(names, i, size);
    			temp = names[i];
    			names[i] = names[minPos];
    			names[minPos] = temp;
    		}
    	}
    	public static int minimunPosition(String[] names, int i, int size)
    	{
    		int minPos = i;
    		int k;
    		for (k = i+1; k < size; k++)
    		{
    			if (names[k].compareTo(names[minPos]) == -1)
    				minPos = k;
    		}
    		return minPos;
    	}
     
    }
    The input that I'm doing is:
    Strickland, Bobby
    Anderson, Brett
    Keefer, Chris
    Whymer, Josh
    END
    the output is the same as above without the END, obviously. I've tried using 1 instead of -1 as the return value of compareTo() but it's stays the same. I've changed the if statement to (name[k].charAt(0) < name[minPos].charAt(0)) but my professor said he'd take off points because he specifically want's me to use the compareTo(). Any help is greatly appreciated.


  2. #2
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    Default

    Hey,
    The code shows that u r assinging names to temp variable...
    how u can assign a string array to string variable?

    Apart from this, every thing looks correct to me.

  3. #3
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    Default Re: Problem with string.compareTo();

    @purvesh: I haven't seen him assigning the array to a variable.

    @Drasumok: Please provide the exact question you need help with? What is the actual input, what is the output? In case of errors or exceptions, post here the full exception trace to get help.
    Anyone who stops learning is old, whether at twenty or eighty. Anyone who keeps learning stays young. The greatest thing in life is to keep your mind young.

    - Henry Ford

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Problem with string.compareTo();

    When does compareTo() return a -1? Where does the API say that value is returned?
    If you don't understand my answer, don't ignore it, ask a question.

  5. The Following User Says Thank You to Norm For This Useful Post:

    purvesh (November 30th, 2012)

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    Default

    Exactly!! Change d condition to less then zero
    Also use compareToIgnoreCase instead of compareTo and compare with names[i] instead of names[minPos]

  7. #6
    Super Moderator Norm's Avatar
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    Default Re: Problem with string.compareTo();

    Please mark this thread as solved if the problem is solved.
    If you don't understand my answer, don't ignore it, ask a question.

  8. #7
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    Default Re: Problem with string.compareTo();

    Quote Originally Posted by Mr.777 View Post
    @purvesh: I haven't seen him assigning the array to a variable.

    @Drasumok: Please provide the exact question you need help with? What is the actual input, what is the output? In case of errors or exceptions, post here the full exception trace to get help.
    Below the code is where I put the input and output of the program, and setting the compareTo() < 0 fixed my problem

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