Please help in this selection sort

[Yazan Rashi]

Hi all,
I'm doing a program which is Selection Sort of an array of String... I want to get a 20 length string consist of letters from a-z and A-Z randomly...
I used String Buffer to get this random string but I'm having problems in doing the selection sort...
This is my code:

import java.util.*;  

public class SelectionSort   
{
	public static Random generator = new Random(); 
	
	public static void main(String[] args)  
    {  
       char[] array = {'Q','A','a','b','c','L','d','U','K','e','H','f','J','g','T','P','X','h','i','F','j','D','O','k','l','N','m','n','B','o','I','p',
                       'G','q','Y','V','r','s','C','t','S','u','M','Z','v','w','W','x','y','E','z','R'};
    
        StringBuffer sb = new StringBuffer();
    	int te=array.length;
        for(int i=0;i<20;i++)
        {
             sb.append(array[generator.nextInt(te)]);
        }
            
        System.out.println("Before sorting:");
    	for (int i = 0; i < array.length; i++) 
        {
        	System.out.print(array[i]+"  ");

        } 
        	
        //Selection Sort    	
        for (int i = 0; i < array.length; i++) 
        {
            int min = i;       
            for (int j = i + 1; j < array.length; j++) 
            {
                if (array[j].charAt(array[min])<0)
                {
                	min = j;
                }
            }
            if (min != i)
            {
            	char temp = array[i];
                array[i] = array[min];
                array[min] = temp;
            }
        }
                
        System.out.println("After sorting:"); 
    	for (int i = 0; i < array.length; i++) 
        {
        	System.out.print(array[i]+"  ");

        }  
    }

Any help is greatly appreciated...

[Campbell Ritchie]

What does the bit about < 0 mean? That looks possibly incorrect to me.
You should lose the te variable and replace it with array.length.
You should move as much code out of the main() method as possible.

[Campbell Ritchie]

. . . and welcome to JavaRanch

[Yazan Rashi]

I used this loop in selection sort with String array and without using StringBuffer... and it worked fine with me...

public static void selectionSort(String[] array)
    {
        for (int i = 0; i < array.length; i++) 
        {
            int min = i;       
            for (int j = i + 1; j < array.length; j++) 
            {
                if (array[j].compareTo(array[min])<0)
                {
                	min = j;
                }
            }
            if (min != i)
            {
            	String temp = array[i];
                array[i] = array[min];
                array[min] = temp;
            }
        }
    }

The difference now is that I'm trying to generate Random String using StringBuffer... and it's something new to me Also, I don't know too much about Char arrays...
Help me please!

[Campbell Ritchie]

What you have posted now is different. You have added compareTo now, which won't work on a char.

Do a search for arithmetic on chars. You will find this, which may help with your chars.

[Yazan Rashi]

Yes, this code I used it with String Array, not Char Array...
Thanks a lot for your replies... I really appreciate your help...

[Campbell Ritchie]

What Char array? Do you mean a char array? The two are different.
You will have to use different techniques for comparing chars from Strings; a reference type and a primitive behave differently.

[Alan Hampson]

I'd ask exactly what kind of "problems" are you having. Compile time? Runtime? Code throws an exception or doesn't run correctly?

A little more detail would help, because the code you posted here won't even compile for me.

Also confusing for me is what you're using the StringBuffer for. You load it with a random set of characters from array, but then you don't use it again.

You are performing operations on array, and those won't affect sb at all, even if they would work. Rethink your logic, then update your code accordingly.