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My assignment is to ask a user for the number of strings he would like to input. Then i will prompt him to right the strings. Then i am supposed to print the stings in alphabetical order. I got most of the assignment done, just need a sorting algorithm such as Bubble sort to finish it. this is my code.

import java.io.*; 
public class sorting
{


private static BufferedReader stdin=new BufferedReader(new InputStreamReader( System.in));

  public static void main(String[] arguments) throws IOException
  {
     System.out.println("How many strings would you like to enter?");
     int stringCount = Integer.parseInt(stdin.readLine());
     String[] stringInput = new String[stringCount];
     for(int i = 0; i < stringCount; i++)
     {
         System.out.print("Could you enter the strings here: ");
         stringInput[i] = stdin.readLine();
     }  
     //Now how do i use a sorting algorithm?
  }
}
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  • en.wikipedia.org/wiki/Bubble_sort. You'll sort the array, doing an alphabetical string comparison. You don't need to sort the characters in the array, just the strings within the array. Commented Aug 2, 2011 at 0:23
  • [Apparently there was an unstated requirement that he NOT use anything in 'java.util'. See stackoverflow.com/questions/6917833/… ] Commented Aug 2, 2011 at 23:10

6 Answers 6

Reset to default
8

Arrays.sort().

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2 Comments

do i ad a ; to the arrays.sort() and do I do anything else because nothing happened when i run the project
Read the API reference I linked you to. (How would a statement Arrays.sort(); know which array to sort?)
3

Use Rhino as a Javascript parser so you can include jQuery into your project. Then sorting becomes trivial as you can just load the Strings into a <table> and run this nifty plugin on it.

^ DO NOT DO THIS. (well if you do, post the source and tell us what grade you got on the assignment ;)

No really, just write bubble sort by yourself. It's not that long. You probably learned the pseudocode in class. If you need an additional reference, take a look at the Wikipedia article on it. If there's something in particular that you don't understand about the algorithm, post a specific question and we'll help you out. Other than that, you look like you're on the right track so far :)

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I almost downvoted this, until I saw "the do not do this please"... Then I laughed!!!
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If this wasn't an exercise you'd just use Arrays.sort(stringInput)

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1 
import java.io.*;
import java.util.*;
public class sorting
{
    public static Scanner input = new Scanner(System.in);
    public static void main(String[] args) throws IOException
    {
         System.out.print("How many strings would you like to enter? ");
         String[] stringInput = new String[Integer.parseInt(input.nextLine())];
         for(int i = 0; i < stringInput.length; i++)
         {
             System.out.print("Could you enter the strings here: ");
             stringInput[i] = input.nextLine();
         }  
         Arrays.sort(stringInput);
         for(String s : stringInput) System.out.println(s);
    }
}
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0

It seems to me that you are not being asked to sort the string array, but to print the strings in alphabetical order, which is likely to be a whole lot uglier but a whole lot simpler.

Once the user has typed all of the input strings, you might choose to iterate over the array stringCount times finding, in each iteration, the lowest-valued string; printing it; and then clearing it so that you won't see it in the next iteration.

BUT if you really are being asked to apply a bubble sort (or any kind of sort) on the array, well, that's a whole 'nother question, namely: how do I write a bubble sort for an array of strings. That's a tricky problem for anyone because the strings in the array are of differing lengths: they cannot just be swapped blindly but have to be written into some temp array somewhere that somehow knows how to accomodate their various lengths.

EDIT: Oh, wait a sec: maybe Java knows all about variable-length strings and how to handle them. If so, I take it all back.

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6 Comments

Why is bubble sorting an array of Strings tricky..? You can bubble sort any ordered set that has a well-defined total ordering.
Could you help me with stringCount you mentioned. How would i use it in my program. Could you specify a little more because i just started a few days ago and don't know the sorting algorithms. My teacher told us to use any type of sorting algorithm
@tskuzzy -- to a C programmer like me, it's as I said in my answer. However, I think maybe Java makes this trickiness disappear.
@Vishal1949 -- stringCount is the variable in your program that dictates the number of strings the user types.
@Pete Wilson: download.oracle.com/javase/6/docs/api/java/lang/… :)
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  1. Just use the Set str = TreeSet();
  2. then loop through the string str.add("z");
  3. when you iterate the str variable it is automatically sorted.
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